[ { "id": "https://authors.library.caltech.edu/records/f9r48-68t37", "eprint_id": 99116, "eprint_status": "archive", "datestamp": "2023-08-19 17:39:34", "lastmod": "2023-10-18 17:52:16", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Capuano-V", "name": { "family": "Capuano", "given": "V." }, "orcid": "0000-0002-6886-5719" }, { "id": "Harvard-A", "name": { "family": "Harvard", "given": "A." } }, { "id": "Lin-Yvette", "name": { "family": "Lin", "given": "Y." } }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "S. J." }, "orcid": "0000-0002-6657-3907" } ] }, "title": "DGNSS-Vision Integration for Robust and Accurate Relative\n Spacecraft Navigation", "ispublished": "unpub", "full_text_status": "public", "note": "The first author was supported by the Swiss National Science Foundation (SNSF). This work was also supported in part by the Jet Propulsion Laboratory (JPL). Government sponsorship is acknowledged. The authors thank F. Y. Hadaegh, A. Rahmani, and S. R. Alimo.\n\n
Accepted Version - DGNSS_Vision_Integration_for_Robust_and_Accurate_Pose_Determination_of_Cooperative_Spacecraft__11_.pdf
", "abstract": "Relative spacecraft navigation based on Global Navigation Satellite System (GNSS) has been already successfully performed in low earth orbit (LEO). Very high accuracy, of the order of the millimeter, has been achieved in postprocessing using carrier phase differential GNSS (CDGNSS) and recovering the integer number of wavelength (Ambiguity)\nbetween the GNSS transmitters and the receiver. However the performance achievable on-board, in real time,\nabove LEO and the GNSS constellation would be significantly lower due to limited computational resources, weaker\nsignals, and worse geometric dilution of precision (GDOP). At the same time, monocular vision provides lower accuracy\nthan CDGNSS when there is significant spacecraft separation, and it becomes even lower for larger baselines and wider field of views (FOVs). In order to increase the robustness, continuity, and accuracy of a real-time on-board\nGNSS-based relative navigation solution in a GNSS degraded environment such as Geosynchronous and High Earth\nOrbits, we propose a novel navigation architecture based on a tight fusion of carrier phase GNSS observations and\nmonocular vision-based measurements, which enables fast autonomous relative pose estimation of cooperative spacecraft\nalso in case of high GDOP and low GNSS visibility, where the GNSS signals are degraded, weak, or cannot be\ntracked continuously.\nIn this paper we describe the architecture and implementation of a multi-sensor navigation solution and validate the\nproposed method in simulation. We use a dataset of images synthetically generated according to a chaser/target relative\nmotion in Geostationary Earth Orbit (GEO) and realistic carrier phase and code-based GNSS observations simulated\nat the receiver position in the same orbits. We demonstrate that our fusion solution provides higher accuracy, higher\nrobustness, and faster ambiguity resolution in case of degraded GNSS signal conditions, even when using high FOV\ncameras.", "date": "2019-09", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20191007-132043345", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191007-132043345", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Swiss National Science Foundation (SNSF)" }, { "agency": "JPL" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "DGNSS_Vision_Integration_for_Robust_and_Accurate_Pose_Determination_of_Cooperative_Spacecraft__11_.pdf", "url": "https://authors.library.caltech.edu/records/f9r48-68t37/files/DGNSS_Vision_Integration_for_Robust_and_Accurate_Pose_Determination_of_Cooperative_Spacecraft__11_.pdf" }, "pub_year": "2019", "author_list": "Capuano, V.; Harvard, A.; et el." }, { "id": "https://authors.library.caltech.edu/records/nn5qr-hqx07", "eprint_id": 97314, "eprint_status": "archive", "datestamp": "2023-08-19 16:32:16", "lastmod": "2023-10-20 22:11:18", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Matsuka-Kai", "name": { "family": "Matsuka", "given": "Kai" }, "orcid": "0000-0003-2116-9756" }, { "id": "Lupu-E-S", "name": { "family": "Lupu", "given": "Elena Sorina" }, "orcid": "0000-0002-3968-2630" }, { "id": "Nakka-Yashwanth-K", "name": { "family": "Nakka", "given": "Yashwanth Kumar" }, "orcid": "0000-0001-7897-3644" }, { "id": "Foust-Rebecca", "name": { "family": "Foust", "given": "Rebecca" }, "orcid": "0000-0003-1470-1716" }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Hadaegh-F-Y", "name": { "family": "Had\u00e6gh", "given": "Fred" } } ] }, "title": "Distributed multi-target relative pose estimation for cooperative spacecraft swarm", "ispublished": "unpub", "full_text_status": "public", "note": "This research was supported in part by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The work of Kai Matsuka was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE 1745301. The work of Rebecca Foust was supported by a NASA Space Technology Research Fellowship (Grant No. NNX15AP48H). Also, we would like to thank Aaron Feldman and Jennifer Sun for their support on the robotic experiments.\n\nAccepted Version - IWSCFF2019_DPE__1_.pdf
", "abstract": "Multi-agent relative state estimation is critical in enabling full swarm autonomy. However, relative pose estimation of hundreds to thousands of cooperative agents is challenging due to limited sensing, limited communication, and scalability. We present a distributed algorithm for cooperative multi-agent localization with both limited relative sensing and communication. Each agent locally exchanges the relative measurements and jointly estimates the relative poses of its local neighbors. Because the algorithm only estimates the local neighbors, the number of states does not grow with the total number of agents given the same local sensing and communication graphs, making the algorithm suitable for swarm application. The proposed algorithm is applied to spacecraft swarm localization and verified in simulation and experiments. Experiments are conducted on Caltech's robotic spacecraft simulators, the Multi-Spacecraft Testbed for Autonomy Research (M-STAR), where each spacecraft uses vision-based relative measurements.", "date": "2019-07-22", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190722-095828499", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-095828499", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA/JPL/Caltech" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1745301" }, { "agency": "NASA Space Technology Research Fellowship", "grant_number": "NNX15AP48H" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "IWSCFF2019_DPE__1_.pdf", "url": "https://authors.library.caltech.edu/records/nn5qr-hqx07/files/IWSCFF2019_DPE__1_.pdf" }, "pub_year": "2019", "author_list": "Matsuka, Kai; Lupu, Elena Sorina; et el." }, { "id": "https://authors.library.caltech.edu/records/11yzk-3pj65", "eprint_id": 92175, "eprint_status": "archive", "datestamp": "2023-08-19 13:38:35", "lastmod": "2023-10-20 00:02:43", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Capuano-V", "name": { "family": "Capuano", "given": "Vincenzo" }, "orcid": "0000-0002-6886-5719" }, { "id": "Alimo-S-R", "name": { "family": "Alimo", "given": "Shahrouz Ryan" } }, { "id": "Ho-Andrew-Q", "name": { "family": "Ho", "given": "Andrew Q." } }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" } ] }, "title": "Robust Features Extraction for On-board Monocular-based Spacecraft Pose Acquisition", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2019 AIAA. \n\nAIAA Paper 2019-2005. \n\nThe first author would like to thank the Swiss National Science Foundation (SNSF), that supported him for this research. The authors also gratefully acknowledge partial funding from Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA) in support of this work. The authors thank F. Y. Hadaegh, A. Stoica, and M. Wolf. In addition, the authors would like to thank Techno System Development s.r.l. that kindly made the images of Tango available for this research study.\n\nAccepted Version - SciTech_2019_paper_Capuano.pdf
", "abstract": "This paper presents the design, implementation, and validation of a robust feature extraction architecture for real-time on-board monocular vision-based pose initialization of a target spacecraft in application to on-orbit servicing and formation flying. The proposed computer vision algorithm is designed to detect the most significant features of an uncooperative target spacecraft in a sequence of two-dimensional input images that are collected on board the chaser spacecraft. A novel approach based on the fusion of multiple and parallel processing streams is proposed to filter a minimum number of extracted true point features, even in case of unfavourable illumination conditions and in presence of Earth in the background. These are then combined into relevant polyline structures that characterize the true geometrical shape of the target spacecraft.", "date": "2019-01", "date_type": "published", "pagerange": "Art. No.-2019-2005", "id_number": "CaltechAUTHORS:20190109-132309708", "isbn": "978-1-62410-578-4", "book_title": "AIAA Scitech 2019 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190109-132309708", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Swiss National Science Foundation (SNSF)" }, { "agency": "NASA/JPL/Caltech" } ] }, "other_numbering_system": { "items": [ { "id": "2019-2005", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2019-2005", "primary_object": { "basename": "SciTech_2019_paper_Capuano.pdf", "url": "https://authors.library.caltech.edu/records/11yzk-3pj65/files/SciTech_2019_paper_Capuano.pdf" }, "pub_year": "2019", "author_list": "Capuano, Vincenzo; Alimo, Shahrouz Ryan; et el." }, { "id": "https://authors.library.caltech.edu/records/63tkr-nrs81", "eprint_id": 92174, "eprint_status": "archive", "datestamp": "2023-08-19 13:38:29", "lastmod": "2023-10-20 00:02:40", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kim-Kyunam", "name": { "family": "Kim", "given": "Kyunam" }, "orcid": "0000-0002-7803-1582" }, { "id": "Rahili-S", "name": { "family": "Rahili", "given": "Salar" } }, { "id": "Shi-Xichen", "name": { "family": "Shi", "given": "Xichen" } }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "Morteza" }, "orcid": "0000-0003-0754-4193" } ] }, "title": "Controllability and Design of Unmanned Multirotor Aircraft Robust to Rotor Failure", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2019 AIAA. \n\nAIAA Paper 2019-1787. \n\nThis work was in part funded by Caltech's Center for Autonomous Systems and Technologies and AeroVironment, Inc. The authors would like to thank Reza Nemovi and Amarbold Batzorig for their help with experiments.\n\nAccepted Version - Controllability_and_Design_of_Unmanned_Multirotor_Aircraft_Robust_to_Rotor_Failure-revised.pdf
", "abstract": "A new design method for multi-rotor aircraft with distributed electric propulsion is presented\nto ensure a property of robustness against rotor failure from the control perspective. Based on the concept of null controllability, a quality measure is derived to evaluate and quantify the performance of a given design with the consideration of rotor failure. An optimization\nproblem whose cost function is based on the quality measure is formulated and its optimal solution identifies a set of optimal design parameters that maximizes an aircraft's ability to control its attitude and hence its position. The effectiveness of the proposed design procedure\nis validated through the results of experimentation with the Autonomous Flying Ambulance model being developed at Caltech's Center for Autonomous Systems and Technologies.", "date": "2019-01", "date_type": "published", "pagerange": "1-13", "id_number": "CaltechAUTHORS:20190109-131619062", "isbn": "978-1-62410-578-4", "book_title": "AIAA Scitech 2019 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190109-131619062", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Center for Autonomous Systems and Technologies" }, { "agency": "AeroVironment" } ] }, "other_numbering_system": { "items": [ { "id": "2019-1787", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" }, { "id": "Center-for-Autonomous-Systems-and-Technologies-(CAST)" } ] }, "doi": "10.2514/6.2019-1787", "primary_object": { "basename": "Controllability_and_Design_of_Unmanned_Multirotor_Aircraft_Robust_to_Rotor_Failure-revised.pdf", "url": "https://authors.library.caltech.edu/records/63tkr-nrs81/files/Controllability_and_Design_of_Unmanned_Multirotor_Aircraft_Robust_to_Rotor_Failure-revised.pdf" }, "pub_year": "2019", "author_list": "Kim, Kyunam; Rahili, Salar; et el." }, { "id": "https://authors.library.caltech.edu/records/rcrtq-ztb53", "eprint_id": 92176, "eprint_status": "archive", "datestamp": "2023-08-19 13:38:40", "lastmod": "2023-10-20 00:02:46", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Foust-Rebecca", "name": { "family": "Foust", "given": "Rebecca" }, "orcid": "0000-0003-1470-1716" }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Hadaegh-F-Y", "name": { "family": "Hadaegh", "given": "Fred Y." } } ] }, "title": "Solving Optimal Control with Nonlinear Dynamics Using Sequential Convex Programming", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2019 AIAA. \n\nAIAA Paper 2019-0652. \n\nThe work of Rebecca Foust was supported by a NASA Space Technology Research Fellowship and in part by the Jet Propulsion Laboratory (JPL). Government sponsorship is acknowledged. The authors also thank Amir Rahmani and Christian Chilan for their technical input.\n\nAccepted Version - Scitech_control_ID_3032436_Foust_GNC_10.pdf
", "abstract": "Sequential convex programming (SCP) is a useful tool in obtaining real-time solutions to direct optimal control, but it is unable to adequately model nonlinear dynamics due to the linearization and discretization required. As nonlinear program solvers are not yet functioning\nin real-time, a tool is needed to bridge the gap between satisfying the nonlinear dynamics and completing execution fast enough to be useful. This paper presents a real-time control algorithm, sequential convex programming with nonlinear dynamics correction (SCPn), which ameliorates the performance of SCP under nonlinear dynamics. Simulations are presented to validate the efficacy of the method.", "date": "2019-01", "date_type": "published", "pagerange": "1-15", "id_number": "CaltechAUTHORS:20190109-132944040", "isbn": "978-1-62410-578-4", "book_title": "AIAA Scitech 2019 Forum", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190109-132944040", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Space Technology Research Fellowship" }, { "agency": "JPL" } ] }, "other_numbering_system": { "items": [ { "id": "2019-0652", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2019-0652", "primary_object": { "basename": "Scitech_control_ID_3032436_Foust_GNC_10.pdf", "url": "https://authors.library.caltech.edu/records/rcrtq-ztb53/files/Scitech_control_ID_3032436_Foust_GNC_10.pdf" }, "pub_year": "2019", "author_list": "Foust, Rebecca; Chung, Soon-Jo; et el." }, { "id": "https://authors.library.caltech.edu/records/97hth-tde87", "eprint_id": 90231, "eprint_status": "archive", "datestamp": "2023-08-19 11:43:03", "lastmod": "2023-10-18 23:18:00", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Foust-Rebecca", "name": { "family": "Foust", "given": "Rebecca C." }, "orcid": "0000-0003-1470-1716" }, { "id": "Lupu-E-S", "name": { "family": "Lupu", "given": "Elena Sorina" }, "orcid": "0000-0002-3968-2630" }, { "id": "Nakka-Yashwanth-K", "name": { "family": "Nakka", "given": "Yashwanth Kumar" }, "orcid": "0000-0001-7897-3644" }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Hadaegh-F-Y", "name": { "family": "Hadaegh", "given": "Fred Y." } } ] }, "title": "Ultra-Soft Electromagnetic Docking with Applications to In-Orbit Assembly", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2018 by the International Astronautical Federation (IAF). \n\nPaper ID: 46481. \n\nThe work of Rebecca Foust was supported by a NASA Space Technology Research Fellowship and in part by the Jet Propulsion Laboratory (JPL). Government sponsorship is acknowledged. The part of the work of Sorina Lupu was in fulfillment of the Swiss Federal Institute of Technology Master Thesis, coordinated by Professor Colin Jones. \n\nThe authors also thank Lorraine Fesq, Issa Nesnas, Marco Quadrelli, Adrian Stoica, Rashied Amini and Michael Wolf for their technical input. \n\nThe authors acknowledge the work done by Richard Eric Rasmussen in designing and constructing the spacecraft simulators. Thanks so much to our wonderful undergraduate students Jui Hung Sun for building the thruster experimental setup and designing version 1 of the thruster control board, David Elliot for improving the thruster control board and so much soldering, Asta Wu for optimizing the docking port design and constructing the ports, Karen Chen for helping with mechanical design of interfaces and Irene Crowell for creating a wonderful software architecture.\n\nIn Press - Ultrasoft_Docking_IAC_2018.pdf
", "abstract": "Docking small satellites in space is a high-risk operation due to the uncertainty in relative position and orientation and the lack of mature docking technologies. This is particularly true for missions that involve multiple docking and undocking procedures like swarm-based construction and reconfiguration. In this paper, an electromagnetic docking system is proposed to mitigate these risks through robust, ultra-soft, propellant-free docking. Designed with reconfigurable self-assembly in mind, the gripping mechanism is androgynous, able to dock at a variety of relative orientations, and tolerant of small misalignments. The mechanical and control design of the system is presented and tested in both simulation and on a fleet of 6 degree-of-freedom (DOF) spacecraft simulators. The spacecraft simulators oat on the precision flat floor facility in the Caltech Aerospace Robotics and Control lab, the largest of its kind at any university. The performance of the electromagnetic docking system on-board the simulators is then compared against a propulsive docking system.", "date": "2018-10", "date_type": "published", "publisher": "International Astronautical Federation", "id_number": "CaltechAUTHORS:20181010-123842437", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181010-123842437", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Space Technology Research Fellowship" }, { "agency": "JPL" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "Ultrasoft_Docking_IAC_2018.pdf", "url": "https://authors.library.caltech.edu/records/97hth-tde87/files/Ultrasoft_Docking_IAC_2018.pdf" }, "pub_year": "2018", "author_list": "Foust, Rebecca C.; Lupu, Elena Sorina; et el." }, { "id": "https://authors.library.caltech.edu/records/2v2h8-jda31", "eprint_id": 90230, "eprint_status": "archive", "datestamp": "2023-08-19 11:42:55", "lastmod": "2023-10-18 23:17:58", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Baldini-F", "name": { "family": "Baldini", "given": "Francesca" } }, { "id": "Harvard-A", "name": { "family": "Harvard", "given": "Alexei" } }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Nesnas-I-A-D", "name": { "family": "Nesnas", "given": "Issa" } }, { "id": "Bhaskaran-S", "name": { "family": "Bhaskaran", "given": "Shyamkumar" } } ] }, "title": "Autonomous Small Body Mapping and Spacecraft Navigation Via Real-Time SPC-SLAM", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2018 by the International Astronautical Federation (IAF). \n\nPaper ID: 47373. \n\nThis work was supported by the Jet Propulsion Laboratory (JPL). Government sponsorship is acknowledged. This research was carried out in part at the JPL, California Institute of Technology, under a contract with NASA. The authors thank Saptarshi Bandyopadhyay and Nick Mastrodemos.\n\nIn Press - IAC_paper_smallbody.pdf
", "abstract": "Current methods for pose and shape estimation of small bodies, such as comets and asteroids, rely on extensive ground support and significant use of radiometric measurements using the Deep Space Network. The Stereo-Photoclinometry (SPC) technique is currently used to provide detailed topological information about a small body as well as its absolute orientation and position. While this technique has produced very accurate estimates, the core algorithm cannot be run in real-time and requires a team of scientists on the ground who must communicate with the spacecraft in order to oversee SPC operations. Autonomous onboard navigation addresses these limitations by eliminating the need for human oversight. In this paper, we present an optimization-based estimation algorithm for navigation that allows the spacecraft to autonomously approach and maneuver around an unknown small body by mapping its geometric shape, estimating its orientation, and simultaneously determining the trajectory of the center of mass of the small body. We show the effectiveness of the proposed algorithm using simulated data from a previous flight mission to Comet 67P.", "date": "2018-10", "date_type": "published", "publisher": "International Astronautical Federation", "id_number": "CaltechAUTHORS:20181010-123200583", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181010-123200583", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA/JPL/Caltech" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "IAC_paper_smallbody.pdf", "url": "https://authors.library.caltech.edu/records/2v2h8-jda31/files/IAC_paper_smallbody.pdf" }, "pub_year": "2018", "author_list": "Baldini, Francesca; Harvard, Alexei; et el." }, { "id": "https://authors.library.caltech.edu/records/y2mvv-yyq90", "eprint_id": 90232, "eprint_status": "archive", "datestamp": "2023-08-19 11:43:12", "lastmod": "2023-10-18 23:18:04", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Capuano-V", "name": { "family": "Capuano", "given": "Vincenzo" }, "orcid": "0000-0002-6886-5719" }, { "id": "Kim-Kyunam", "name": { "family": "Kim", "given": "Kyunam" }, "orcid": "0000-0002-7803-1582" }, { "id": "Hu-Juliette", "name": { "family": "Hu", "given": "Juliette" } }, { "id": "Harvard-A", "name": { "family": "Harvard", "given": "Alexei" } }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" } ] }, "title": "Monocular-Based Pose Determination of Uncooperative Known and Unknown Space Objects", "ispublished": "unpub", "full_text_status": "public", "keywords": "Vision-based Navigation, Spacecraft, Pose Determination", "note": "\u00a9 2018 by the International Astronautical Federation (IAF). \n\nPaper ID: 46801. \n\nThe first author was supported by the Swiss National Science Foundation (SNSF). This work was also supported in part by the Jet Propulsion Laboratory (JPL). Government sponsorship is acknowledged. The authors thank F. Y. Hadaegh, A. Stoica, M. Wolf, S. R. Alimo, and M. Quadre.\n\nIn Press - 2018_-_V._Capuano_et_al.__IAC2018_.pdf
", "abstract": "In order to support spacecraft proximity operations, such as on-orbit servicing and spacecraft formation flying, several vision-based techniques exist to determine the relative pose of an uncooperative orbiting object with respect to the spacecraft. Depending on whether the object is known or unknown, a shape model of the orbiting target object may have to be constructed autonomously by making use of only optical measurements. In this paper, we investigate two vision-based approaches for pose estimation of uncooperative orbiting targets: one that is general and versatile such that it does not require a priori knowledge of any information of the target, and the other one that requires knowledge of the target's shape geometry. The former uses an estimation algorithm of translational and rotational dynamics to sequentially perform simultaneous pose determination and 3D shape reconstruction of the unknown target, while the latter relies on a known 3D model of the target's geometry to provide a point-by-point pose solution. The architecture and implementation of both methods are presented and their achievable performance is evaluated through numerical simulations. In addition, a computer vision processing strategy for feature detection and matching and the Structure from Motion (SfM) algorithm for on-board 3D reconstruction are also discussed and validated by using a dataset of images that are synthetically generated according to a chaser/target relative motion in Geosynchronous Orbit (GEO).", "date": "2018-10", "date_type": "published", "publisher": "International Astronautical Federation", "id_number": "CaltechAUTHORS:20181010-125059291", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181010-125059291", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Swiss National Science Foundation (SNSF)" }, { "agency": "JPL" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "2018_-_V._Capuano_et_al.__IAC2018_.pdf", "url": "https://authors.library.caltech.edu/records/y2mvv-yyq90/files/2018_-_V._Capuano_et_al.__IAC2018_.pdf" }, "pub_year": "2018", "author_list": "Capuano, Vincenzo; Kim, Kyunam; et el." }, { "id": "https://authors.library.caltech.edu/records/fe3er-haq75", "eprint_id": 87627, "eprint_status": "archive", "datestamp": "2023-08-19 04:58:36", "lastmod": "2023-10-18 21:19:37", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Foust-Rebecca", "name": { "family": "Foust", "given": "Rebecca C." }, "orcid": "0000-0003-1470-1716" }, { "id": "Zhao-Michelle", "name": { "family": "Zhao", "given": "Michelle" } }, { "id": "Oliver-Suzanne", "name": { "family": "Oliver", "given": "Suzanne" } }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Hadaegh-F-Y", "name": { "family": "Hadaegh", "given": "Fred Y." } } ] }, "title": "Distributed Control Of An Evolving Satellite Assembly During In-Orbit Construction", "ispublished": "unpub", "full_text_status": "public", "keywords": "Control Allocation, Self-Assembly, Autonomy", "note": "This work was supported by a NASA Space Technology Research Fellowship. Government sponsorship is acknowledged. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the NASA.\n\nUpdated - IAC-2017-Control_of_Evolving_Structure_Updated.pdf
", "abstract": "This paper presents a method for controlling sets of docked satellites during in-orbit construction of a large-scale satellite assembly from a swarm of heterogeneous satellites. Such a system can be used to enable missions from sparse aperture telescopes to elaborate space stations. Once two or more agents from the swarm are docked, the resulting assembly is an over-actuated system so position and attitude controllers must determine which of the available actuators to use. Typically, control allocation for over-actuated systems is done using a simple linear program, but for this scheme the mass properties and number of control points changes. As a result, the linear program solved changes with each new agent that docks with the assembly so the agents must know how to alter the linear program for additional agents and remove control points whose plumes would interact with those agents. In most systems, this linear program is solved by a central computer, but for this system the actuators belong to distinct agents so to increase reliability, each agent solves the same linear program and executes its portion of the resulting control command. This paper sets up the general linear program that each agent in the assembly must solve and then establishes the rules for altering that program when new agents dock. Initial simulations allow the agents to dock as they come into proximity along their respective trajectories to their target locations. This can lead to instability and uncontrollability if the agents dock in certain configurations, so the control allocation rules are extended to prevent uncontrollable or unstable docking scenarios. The logic used for this is based on the moment of inertia and the available actuation ability. Simulations in 6DOF perturbed satellite dynamics show the efficacy of this approach in preventing uncontrollable assemblies and bringing the assemblies together into the desired final configuration.", "date": "2018-07-06", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20180706-160821260", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180706-160821260", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA Space Technology Research Fellowship" }, { "agency": "NASA/JPL/Caltech" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "IAC-2017-Control_of_Evolving_Structure_Updated.pdf", "url": "https://authors.library.caltech.edu/records/fe3er-haq75/files/IAC-2017-Control_of_Evolving_Structure_Updated.pdf" }, "pub_year": "2018", "author_list": "Foust, Rebecca C.; Zhao, Michelle; et el." }, { "id": "https://authors.library.caltech.edu/records/75b7p-gwb14", "eprint_id": 83505, "eprint_status": "archive", "datestamp": "2023-08-19 04:04:24", "lastmod": "2023-10-17 23:10:52", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Saxton-Fox-T", "name": { "family": "Saxton-Fox", "given": "Theresa" }, "orcid": "0000-0003-1328-4148" }, { "name": { "family": "McKeon", "given": "Beverley" } } ] }, "title": "Modeling momentum and scalar transport in a wall-bounded turbulent flow", "ispublished": "unpub", "full_text_status": "public", "note": "Conference presentation, session 4C-2. \n\nThe authors would like to acknowledge the support of the Air Force, which made this work possible through a National Defense Science and Engineering Graduate Fellowship and two grants overseen by Doug Smith, #FA9550-12-1-0060 and #FA9550-16-1-0361. Additionally, the authors thank Dr. Scott Dawson for his assistance with the resolvent code in the boundary layer geometry.\n\nAccepted Version - 332.pdf
", "abstract": "A mildly-heated turbulent boundary layer was studied to characterize the relationship between velocity structures and the scalar field. Particle image velocimetry (PIV) and a Malley probe (Malley et al., 1992) were used to simultaneously measure the velocity field and the streamwise gradients of the scalar field (Gordeyev et al., 2014) respectively. Two distinct velocity scales were identified to be correlated to scalar mixing by conditionally averaging the velocity field on the existence of a scalar gradient. Resolvent analysis was used to create simple models of these velocity scales (McKeon and Sharma, 2010) and to probe their interaction. Using a combination of structural conditional averaging and conditional averaging on the scalar gradient, significant interaction was observed between the two scales of interest, with behavior consistent with the general scale interaction described by amplitude modulation (Hutchins and Marusic, 2007). The study constructed a model of the velocity field that was correlated to streamwise scalar gradients in the outer boundary layer.", "date": "2017-11-28", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20171128-103322689", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171128-103322689", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Defense Science and Engineering Graduate Fellowship (NDSEG)" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0060" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-16-1-0361" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "332.pdf", "url": "https://authors.library.caltech.edu/records/75b7p-gwb14/files/332.pdf" }, "pub_year": "2017", "author_list": "Saxton-Fox, Theresa and McKeon, Beverley" }, { "id": "https://authors.library.caltech.edu/records/zjgb3-gwh82", "eprint_id": 83521, "eprint_status": "archive", "datestamp": "2023-08-20 07:09:40", "lastmod": "2023-10-17 23:11:49", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gordeyev-S", "name": { "family": "Gordeyev", "given": "Stanislav" } }, { "id": "Smith-A-E", "name": { "family": "Smith", "given": "Adam E." } }, { "id": "Saxton-Fox-T", "name": { "family": "Saxton-Fox", "given": "Theresa" }, "orcid": "0000-0003-1328-4148" }, { "name": { "family": "McKeon", "given": "Beverley" } } ] }, "title": "Studies of the large-scale structure in adiabatic and moderately-wall-heated subsonic boundary layers", "ispublished": "unpub", "full_text_status": "public", "note": "SESSION 7A - Wall Turbulence: Large Structures. \n\nThe support of the Department of Defense through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program and the Air Force Office of Scientific Research Grant # FA9550-12-1-0060 are gratefully acknowledged. The U.S. Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation thereon.\n\nAccepted Version - 7A-3.pdf
", "abstract": "Simultaneous velocity-optical measurements in subsonic boundary layers were conducted in order to investigate the relationship between the instantaneous 2-D wavefronts, measured by different optical sensors, the Malley probe and 2-D Shack-Hartmann sensors, and the instantaneous large-scale structure along a wall-normal plane, using PIV in both incompressible and compressible subsonic boundary layers. These systematic studies of the instantaneous relation between the large-scale boundary layer structure and its aero-optical signature provide additional understanding of the instantaneous dynamics of the large-scale structure at subsonic and transonic speeds.", "date": "2017-11-28", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20171128-113834714", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171128-113834714", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "National Defense Science and Engineering Graduate (NDSEG) Fellowship" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0060" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "7A-3.pdf", "url": "https://authors.library.caltech.edu/records/zjgb3-gwh82/files/7A-3.pdf" }, "pub_year": "2017", "author_list": "Gordeyev, Stanislav; Smith, Adam E.; et el." }, { "id": "https://authors.library.caltech.edu/records/k40ec-b8503", "eprint_id": 77117, "eprint_status": "archive", "datestamp": "2023-08-19 02:19:24", "lastmod": "2023-10-25 21:53:34", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lhota-R", "name": { "family": "Lhota", "given": "Red" } }, { "id": "McMullen-R-M", "name": { "family": "McMullen", "given": "Ryan" }, "orcid": "0000-0003-1371-7150" }, { "id": "Huynh-David", "name": { "family": "Huynh", "given": "David" } }, { "id": "Wei-Ming-Hsin", "name": { "family": "Wei", "given": "Ming-Hsin" } }, { "id": "Kornfield-J-A", "name": { "family": "Kornfield", "given": "Julia A." }, "orcid": "0000-0001-6746-8634" }, { "name": { "family": "McKeon", "given": "Beverley" }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Megasupramolecules as molecular probes of turbulence", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2017 American Chemical Society.", "abstract": "Ultralong polymers in dil. soln. have been known since the 1940s to significantly modify turbulent flow, a phenomenon called drag redn., but these long covalent chains suffer from bond scission under stress. As a result of degrdn. and the complexity of turbulence, the mechanism of how long chains impact flow is still not well understood. To imitate ultralong polymers and study the interaction between chains and turbulence, we use long end-associative polymers with hydrogen-bonding end-groups that link in soln. at low concns. to form multi-million mol. wt. supramols. (megasupramols.). These megasupramols. can stretch to\nmicrons in length, while reversibly breaking and reforming in flow conditions, and can be designed to target different length and energy scales in turbulence. Changing the backbone length of the associative units adjusts the reach of the megasupramols., both in the coiled and stretched states. Changing the assocn. strength by choosing alternate functional groups adjusts the stress the megasupramol. will withstand before disassocg. The action of the mols. on the flow is obsd. through particle imaging velocimetry, a technique for detg. detailed velocity profiles and fluctuations, with increased reproducibility due to the ability of the megasupramols. to reversibly associative instead of permanently degrading. Using these megasupramols. as probes explores suppression of different turbulence modes as a route to understand both how drag redn. occurs in polymer solns. and how turbulence can be characterized and manipulated.", "date": "2017-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20170502-080408690", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170502-080408690", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2017", "author_list": "Lhota, Red; McMullen, Ryan; et el." }, { "id": "https://authors.library.caltech.edu/records/rbg0t-0dv69", "eprint_id": 70375, "eprint_status": "archive", "datestamp": "2023-08-20 13:08:48", "lastmod": "2023-10-20 22:53:39", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gat-Ilana", "name": { "family": "Gat", "given": "Ilana" }, "orcid": "0000-0003-0223-0507" }, { "id": "Matheou-Georgios", "name": { "family": "Matheou", "given": "Georgios" }, "orcid": "0000-0003-4024-4571" }, { "id": "Chung-Daniel", "name": { "family": "Chung", "given": "Daniel" }, "orcid": "0000-0003-3732-364X" }, { "id": "Dimotakis-P-E", "name": { "family": "Dimotakis", "given": "Paul E." } } ] }, "title": "Acceleration-driven variable-density turbulent flow", "ispublished": "unpub", "full_text_status": "public", "note": "The work is supported by DOE Grant DE-NA0002382, AFOSR Grant FA9550-12-1-0461, NSF GRFP under Grant DGE-1144469, Caltech, and Blue Waters PRAC, supported by NSF OCI-0725070 and ACI-1238993, and Illinois. Data-storage/-visualization computer cluster, integrated by Daniel Lang and developed with support by NSF MRI Grant EIA-0079871, is used. Computations are also performed on the Caltech Zwicky computer cluster, supported by NSF MRI-R2 PHY-0960291 and by the Sherman Fairchild Foundation. The work was also supported by the Cray Trinity system of ACES, a partnership between LANL and SNL for the U.S. DOE's NNSA. We would like to acknowledge discussions with Profs. Dan Meiron and Dale Pullin, and the collaboration with Prof. Christian Ott in the computations. \n\nNote: An error was noted in the alignment statistics of vorticity and baroclinic torques in the originally posted paper and conference presentation. The present typescript is an update without the corresponding sections. The authors regret the original error.\n\nAccepted Version - eScholarship_UC_item_61d722q6.pdf
", "abstract": "We discuss turbulent dynamics and mixing of a variable-density flow subject to a uniform-acceleration field. The \nflow and misalignments of pressure and density gradients are\ninvestigated for small to large density ratios, with evidence that the small-density ratio flow is described by the Boussinesq approximation. A new shear-layer growth rate is reported, along with an extension of uniform-density \nflow vorticity-alignment statistics in the variable-density \now studied. Spectra collapse when properly scaled for variable density.", "date": "2016-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20160915-111630955", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160915-111630955", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-NA0002382" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0461" }, { "agency": "NSF Graduate Research Fellowship", "grant_number": "DGE-1144469" }, { "agency": "Caltech" }, { "agency": "Blue Waters PRAC" }, { "agency": "NSF", "grant_number": "OCI-0725070" }, { "agency": "NSF", "grant_number": "ACI-1238993" }, { "agency": "NSF", "grant_number": "EIA-0079871" }, { "agency": "NSF", "grant_number": "PHY-0960291" }, { "agency": "Sherman Fairchild Foundation" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "eScholarship_UC_item_61d722q6.pdf", "url": "https://authors.library.caltech.edu/records/rbg0t-0dv69/files/eScholarship_UC_item_61d722q6.pdf" }, "pub_year": "2016", "author_list": "Gat, Ilana; Matheou, Georgios; et el." }, { "id": "https://authors.library.caltech.edu/records/3kd0e-b9j39", "eprint_id": 72607, "eprint_status": "archive", "datestamp": "2023-08-20 10:24:48", "lastmod": "2023-10-23 22:46:04", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Foust-Rebecca", "name": { "family": "Foust", "given": "Rebecca" }, "orcid": "0000-0003-1470-1716" }, { "id": "Chung-Soon-Jo", "name": { "family": "Chung", "given": "Soon-Jo" }, "orcid": "0000-0002-6657-3907" }, { "id": "Hadaegh-F-Y", "name": { "family": "Hadaegh", "given": "Fred Y." } } ] }, "title": "Real-Time Optimal Control and Target Assignment for Autonomous In-Orbit Satellite Assembly from a Modular Heterogeneous Swarm", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2016 American Astronomical Society AAS.\n\nSubmitted - AAS_Feb1216.pdf
", "abstract": "This paper presents a decentralized optimal guidance and control scheme to combine a heterogeneous swarm of component satellites, rods and connectors, into a large satellite structure. By expanding prior work on a decentralized auction algorithm with model predictive control using sequential convex programming (MPC-SCP) to allow for the limited type heterogeneity and docking ability required for in-orbit assembly. The assignment is performed using a distributed auction with a variable number of targets and strict bonding rules to address the heterogeneity. MPC-SCP is used to generate the collision-free trajectories, with modifications to the constraints to allow docking.", "date": "2016-02-18", "date_type": "published", "publisher": "American Astronomical Society AAS", "id_number": "CaltechAUTHORS:20161206-152153163", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161206-152153163", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "AAS_Feb1216.pdf", "url": "https://authors.library.caltech.edu/records/3kd0e-b9j39/files/AAS_Feb1216.pdf" }, "pub_year": "2016", "author_list": "Foust, Rebecca; Chung, Soon-Jo; et el." }, { "id": "https://authors.library.caltech.edu/records/3exxw-gfv33", "eprint_id": 64480, "eprint_status": "archive", "datestamp": "2023-08-20 09:43:32", "lastmod": "2023-10-17 21:26:14", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ranande-P", "name": { "family": "Ranande", "given": "Piyush" } }, { "id": "Duvvuri-S", "name": { "family": "Duvvuri", "given": "Subrahmanyam" }, "orcid": "0000-0001-8082-1658" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "Beverley" }, "orcid": "0000-0003-4220-1583" }, { "id": "Gordeyev-S", "name": { "family": "Gordeyev", "given": "Stanislav" } }, { "id": "Christensen-K", "name": { "family": "Christensen", "given": "Kenneth" } }, { "id": "Jumper-E", "name": { "family": "Jumper", "given": "Eric" } } ] }, "title": "Turbulence Amplitude Modulation in an Externally Forced, Subsonic Turbulent Boundary Layer", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2016 AIAA. \n\nThis effort were funded in part by the High Energy Laser - Joint Technology Office (HEL-JTO) and administered through the Air Force Office for Scientific Research (AFOSR) under Grant Number FA9550-13-1-0001. The U.S. Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation thereon.", "abstract": "This paper describes an experiment in which a forced shear layer external to a turbulent boundary layer is used to impart external large-scale forcing to the boundary layer. The shear-layer forcing creates periodic coherent vortical structures in the shear layer that convect at the shear-layer convective velocity. The convecting coherent structures create a concomitant unsteady pressure field that provides a disturbance for the turbulent boundary layer on the upper wall of the tunnel above the forced shear layer. The unsteady pressure field in turn creates a variation of the effective freestream velocity experienced by the boundary layer, and both the pressure disturbance and the concomitant velocity fluctuations are reported. The character of the turbulence in the boundary layer due to the external forcing is studied through hot-wire anemometry. Thorough examination of the turbulence results in similarities between the turbulence amplitude modulation results due to these externally-forced experiments and modulation response of an internally-forced boundary layer done by others.", "date": "2016-01", "date_type": "published", "id_number": "CaltechAUTHORS:20160212-132731202", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160212-132731202", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-13-1-0001" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2016-1120", "pub_year": "2016", "author_list": "Ranande, Piyush; Duvvuri, Subrahmanyam; et el." }, { "id": "https://authors.library.caltech.edu/records/25xt7-v2813", "eprint_id": 50272, "eprint_status": "archive", "datestamp": "2023-08-19 11:40:20", "lastmod": "2023-10-17 22:53:36", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Austin-J-M", "name": { "family": "Austin", "given": "J. M." } }, { "id": "Pintgen-F", "name": { "family": "Pintgen", "given": "F." } }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "J. E." }, "orcid": "0000-0003-3181-9310" } ] }, "title": "Visualizations of reaction zones in highly unstable detonations", "ispublished": "unpub", "full_text_status": "public", "date": "2014-10-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141008-125745439", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-125745439", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "Austin, J. M.; Pintgen, F.; et el." }, { "id": "https://authors.library.caltech.edu/records/s437a-a5h69", "eprint_id": 50276, "eprint_status": "archive", "datestamp": "2023-08-19 20:32:08", "lastmod": "2023-10-17 22:53:42", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Parker-M-D", "name": { "family": "Parker", "given": "M. D." } }, { "id": "Austin-J-M", "name": { "family": "Austin", "given": "J. M." } } ] }, "title": "Shock-induced void collapse mechanisms in detonation initiation", "ispublished": "unpub", "full_text_status": "public", "date": "2014-10-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141008-132029247", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-132029247", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "Parker, M. D. and Austin, J. M." }, { "id": "https://authors.library.caltech.edu/records/ky2v2-01m46", "eprint_id": 50275, "eprint_status": "archive", "datestamp": "2023-08-19 16:00:49", "lastmod": "2023-10-17 22:53:40", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Austin-J-M", "name": { "family": "Austin", "given": "J. M." } }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "J. E." }, "orcid": "0000-0003-3181-9310" } ] }, "title": "Characterizing the fluctuations in gaseous detonation", "ispublished": "unpub", "full_text_status": "public", "date": "2014-10-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141008-131610611", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-131610611", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "Austin, J. M. and Shepherd, J. E." }, { "id": "https://authors.library.caltech.edu/records/t2hdq-65m65", "eprint_id": 50274, "eprint_status": "archive", "datestamp": "2023-08-19 07:56:08", "lastmod": "2023-10-20 21:50:20", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Pintgen-Florian", "name": { "family": "Pintgen", "given": "F." } }, { "id": "Eckett-Christopher-A", "name": { "family": "Eckett", "given": "C. A." } }, { "id": "Austin-J-M", "name": { "family": "Austin", "given": "J. M." }, "orcid": "0000-0003-3129-5035" }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "J. E." }, "orcid": "0000-0003-3181-9310" } ] }, "title": "Direct observations of reaction zone structure in propagating detonations", "ispublished": "unpub", "full_text_status": "public", "date": "2014-10-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141008-130337883", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-130337883", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "Pintgen, F.; Eckett, C. A.; et el." }, { "id": "https://authors.library.caltech.edu/records/0e1yc-q5e10", "eprint_id": 50273, "eprint_status": "archive", "datestamp": "2023-08-19 04:30:09", "lastmod": "2023-10-17 22:53:38", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Austin-J-M", "name": { "family": "Austin", "given": "J. M." } }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "J. E." }, "orcid": "0000-0003-3181-9310" } ] }, "title": "Carbon monoxide detonations", "ispublished": "unpub", "full_text_status": "public", "date": "2014-10-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141008-130006425", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-130006425", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "Austin, J. M. and Shepherd, J. E." }, { "id": "https://authors.library.caltech.edu/records/w8n3j-6z527", "eprint_id": 50257, "eprint_status": "archive", "datestamp": "2023-08-19 07:23:31", "lastmod": "2023-10-17 22:53:00", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "M\u00e9vel-R", "name": { "family": "M\u00e9vel", "given": "R\u00e9my" }, "orcid": "0000-0002-0032-350X" }, { "id": "Davidenko-D", "name": { "family": "Davidenko", "given": "Dmitry" } }, { "id": "Pintgen-F", "name": { "family": "Pintgen", "given": "Florian" } }, { "id": "Austin-J-M", "name": { "family": "Austin", "given": "Joanna" } }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "Joseph" }, "orcid": "0000-0003-3181-9310" } ] }, "title": "Application of a laser induced fluorescence model to the numerical simulation of detonation waves", "ispublished": "unpub", "full_text_status": "public", "note": "Paper #280.", "abstract": "Although numerical simulations have become an essential tool for detonation dynamics understanding, most of the\nphysical constraints that exist within experiments are not accounted for which makes difficult a comparison. In the\npresent study, a simple laser induced fluorescence model has been implemented and used to post-treat detonation wave\nnumerical simulation results and allow a direct comparison with previous experimental visualizations of detonations in\nhydrogen-oxygen-diluent mixtures. The model is first applied to steady one-dimensional simulation results obtained with\ndetailed chemistry. The effects on the fluorescence intensity of the model parameters are examined to underline the\ndominant processes. The model is then applied to unsteady two-dimensional simulation results obtained with reduced\nchemical schemes and a comparison is made with existing experimental data. The results essentially demonstrate good\nqualitative agreement between the experimental and calculated laser induced fluorescence intensities.", "date": "2014-10-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141008-091850465", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-091850465", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "M\u00e9vel, R\u00e9my; Davidenko, Dmitry; et el." }, { "id": "https://authors.library.caltech.edu/records/n5nxh-rz162", "eprint_id": 50220, "eprint_status": "archive", "datestamp": "2023-08-19 00:43:14", "lastmod": "2023-10-17 22:51:32", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Shukla-R-K", "name": { "family": "Shukla", "given": "R. K." } }, { "id": "Pantano-C", "name": { "family": "Pantano", "given": "C." } }, { "id": "Jackson-T-L", "name": { "family": "Jackson", "given": "T. L." } }, { "id": "Austin-J-M", "name": { "family": "Austin", "given": "J. M." } }, { "id": "Freund-J-B", "name": { "family": "Freund", "given": "J. B." } } ] }, "title": "Shock induced detonations in composite heterogeneous energetic materials", "ispublished": "unpub", "full_text_status": "public", "date": "2014-10-07", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20141007-081845149", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141007-081845149", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2014", "author_list": "Shukla, R. K.; Pantano, C.; et el." }, { "id": "https://authors.library.caltech.edu/records/7pgh9-fk866", "eprint_id": 51442, "eprint_status": "archive", "datestamp": "2023-08-20 01:11:15", "lastmod": "2023-10-18 16:29:07", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Smith-A-E", "name": { "family": "Smith", "given": "Adam E." } }, { "id": "Gordeyev-S", "name": { "family": "Gordeyev", "given": "Stanislav" } }, { "id": "Saxton-Fox-T", "name": { "family": "Saxton-Fox", "given": "Theresa" }, "orcid": "0000-0003-1328-4148" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "Beverley" }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Subsonic Boundary-Layer Wavefront Spectra for a Range of Reynolds Numbers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a92014 AIAA. \n\nThis work is supported by the Air Force Office of Scientific Research, Grant number FA9550-12-1-0060. The\nU.S. Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any \ncopyright notation thereon\n\nSubmitted - AIAA-2014-2491.pdf
", "abstract": "Aero-optic measurements of turbulent boundary layers were performed in wind tunnels at the University of Notre Dame and California Institute of Technology for heated walls at a\nrange of Reynolds numbers. Temporally resolved measurements of wavefronts were collected at a range of Mach numbers between 0.03 and 0.4 and the range of Re_\u03b8 between\n1,700 and 20,000. Wavefront spectra for both heated and un-heated walls were extracted and compared to demonstrate that wall heating does not noticeably alter the shape of\nwavefront spectra in the boundary layer. The effect of Reynolds number on the normalized spectra was also presented, and an empirical spectral model was modified to account for Reynolds number dependence. Measurements of OPD_(rms) for heated walls were shown to be consistent with results from prior experiments, and a method of estimating OPD_(rms) and other boundary layer statistics from wavefront measurements of heated-wall boundary layers was demonstrated and discussed.", "date": "2014-06", "date_type": "published", "id_number": "CaltechAUTHORS:20141107-115405464", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-115405464", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0060" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2014-2491", "primary_object": { "basename": "AIAA-2014-2491.pdf", "url": "https://authors.library.caltech.edu/records/7pgh9-fk866/files/AIAA-2014-2491.pdf" }, "pub_year": "2014", "author_list": "Smith, Adam E.; Gordeyev, Stanislav; et el." }, { "id": "https://authors.library.caltech.edu/records/1hep3-rxz69", "eprint_id": 54633, "eprint_status": "archive", "datestamp": "2023-08-20 01:12:23", "lastmod": "2023-10-20 19:11:31", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Dunne-R", "name": { "family": "Dunne", "given": "R." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Dynamic separation on a pitching and surging airfoil as a model for flow over vertical axis wind turbine blades", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a92014 AIAA. \n\nThis work was supported by the Gordon and Betty Moore Foundation through grant GBMF#2645 to the California Institute of Technology. The authors thank Professor Peter J. Schmid for his assistance in implementing the dynamic mode decomposition algorithm. Professor Morteza Gharib for the use of the free surface water channel facility, Hsieh-Chen Tsai and Professor Tim Colonius for discussion on the Coriolis effect and Professor John Dabiri for his insight from VAWT field research.\n\nSubmitted - Dunne_AIAA_2014.pdf
", "abstract": "Vertical axis wind turbine (VAWT) blades undergo dynamic separation due to the large angle of attack variation they experience during a turbine rotation. The flow over a single\nblade was modeled using a sinusoidally pitching and surging airfoil in a constant free stream flow at a mean chord Reynolds number of 10^5. Two-dimensional, time resolved velocity fields were acquired using particle image velocimetry (PIV). Vorticity contours were used to visualize shear layer and vortex activity. A low order model of dynamic separation was developed using Dynamic Mode Decomposition (DMD). A primary and secondary dynamic separation mode were identified as the critical drivers for the unsteady flow field.", "date": "2014-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150210-091011617", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150210-091011617", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF2645" } ] }, "other_numbering_system": { "items": [ { "id": "2014-3142", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2014-3142", "primary_object": { "basename": "Dunne_AIAA_2014.pdf", "url": "https://authors.library.caltech.edu/records/1hep3-rxz69/files/Dunne_AIAA_2014.pdf" }, "pub_year": "2014", "author_list": "Dunne, R. and McKeon, B. J." }, { "id": "https://authors.library.caltech.edu/records/b26s1-8b849", "eprint_id": 47154, "eprint_status": "archive", "datestamp": "2023-08-20 01:08:05", "lastmod": "2023-10-26 20:21:31", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Duvvuri-S", "name": { "family": "Duvvuri", "given": "Subrahmanyam" }, "orcid": "0000-0001-8082-1658" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "Beverley J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Phase relationships in presence of a synthetic large-scale in a turbulent boundary layer", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a92014 AIAA. \n\nThe support of AFOSR (grant FA-9550-12-1-0469, program manager D. Smith) and a Resnick Sustainability Institute Graduate Research Fellowship (S.D.) is gratefully acknowledged.\n\nSubmitted - Duvvuri_McKeon_2014_AIAA.pdf
", "abstract": "A synthetic spanwise-constant spatio-temporal mode is excited in a flat plate turbulent boundary layer through a spatially impulsive patch of dynamic wall-roughness. The streamwise wavelength of the synthetic mode approximately corresponds to the very large-scale motions present in high Reynolds number wall turbulence. Hot wire anemometer measurements made downstream of the roughness forcing reveal the nature of the two dimensional synthetic large-scale and its influence on the small-scale turbulence. A clear phase organizing effect on the small-scales is noticed in presence of the synthetic large-scale. A thorough understanding of these phase relations lays the foundation for a framework that allows for practical manipulation of energetic small-scale turbulence through large-scale inputs by utilizing the inherent non-linear coupling present in the governing Navier-Stokes equations.", "date": "2014-06", "date_type": "published", "id_number": "CaltechAUTHORS:20140713-153917772", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140713-153917772", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA-9550-12-1-0469" } ] }, "other_numbering_system": { "items": [ { "id": "2014-2883", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.2514/6.2014-2883", "primary_object": { "basename": "Duvvuri_McKeon_2014_AIAA.pdf", "url": "https://authors.library.caltech.edu/records/b26s1-8b849/files/Duvvuri_McKeon_2014_AIAA.pdf" }, "pub_year": "2014", "author_list": "Duvvuri, Subrahmanyam and McKeon, Beverley J." }, { "id": "https://authors.library.caltech.edu/records/qqtb0-4bq63", "eprint_id": 51465, "eprint_status": "archive", "datestamp": "2023-08-19 22:57:17", "lastmod": "2023-10-18 16:45:03", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "A." }, "orcid": "0000-0002-7170-1627" }, { "id": "Moarref-R", "name": { "family": "Moarref", "given": "R." } }, { "id": "Luhar-M", "name": { "family": "Luhar", "given": "M." } }, { "id": "Goldstein-D-B", "name": { "family": "Goldstein", "given": "D. B." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Effects of a gain-based optimal forcing on turbulent channel flow", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2014 AIAA. \n\nThis work is supported by the Air Force Office of Scientific Research under a Basic Research Initiative grant, # FA9550-12-1-0469 (program manager Dr. Doug Smith). The computational support for the simulations is provided by Texas Advanced Computing Center (TACC).", "abstract": "The effects of introducing a two- or three-dimensional streamwise traveling wave type body forcing in a turbulent channel flow at Re_\u03c4 = 180 are investigated using direct numerical simulations (DNS). The optimal forcing shape (that is, the forcing that leads to the most amplified or\nhighest-gain velocity response) is obtained from the resolvent analysis of McKeon & Sharma (2010) for wave-numbers and wave-speed representative of the near-wall cycle. The velocity response due to imposed forcing obtained from DNS is found to agree well with resolvent\nanalysis predictions at small forcing amplitude. The changes in mean velocity, shear stress and kinetic energy are characterized for various amplitudes of forcing.", "date": "2014-01", "date_type": "published", "id_number": "CaltechAUTHORS:20141107-145723375", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-145723375", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0469" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2014-1450", "pub_year": "2014", "author_list": "Sharma, A.; Moarref, R.; et el." }, { "id": "https://authors.library.caltech.edu/records/v16ve-vax43", "eprint_id": 41425, "eprint_status": "archive", "datestamp": "2023-08-19 20:56:18", "lastmod": "2023-10-24 23:43:34", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Saito-Kazuya", "name": { "family": "Saito", "given": "Kazuya" } }, { "id": "Pellegrino-S", "name": { "family": "Pellegrino", "given": "Sergio" }, "orcid": "0000-0001-9373-3278" }, { "id": "Nojima-Taketoshi", "name": { "family": "Nojima", "given": "Taketoshi" } } ] }, "title": "Manufacture of Arbitrary Cross-Section Composite Honeycomb Cores Based on Origami Techniques", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2013 ASME.\n\nThis work has been supported by Grant-in-Aid for JSPS Fellows (19-5987) by the Japan Society for Promotion of Sciences.\n\nPublished - DETC2013-12743.pdf
", "abstract": "In recent years, the use of composite materials has drastically increased in the construction of aerospace components. In the case of sandwich panels, they have been extensively used as face sheets with aluminum honeycomb cores. Currently, space structures are increasing in size and require greater degrees of accuracy; hence, the use of composites as a core material is a natural progression. However, these composite core materials are not regularly used in sandwich construction. Compared to standard aluminum honeycombs, their manufacturing costs are very high and they have limited applications. Another problem is difficulty of machining. In the manufacture of complex-shaped parts, the cores must have some degree of curvature. For aluminum honeycombs, this can be done using a contour cutter, a 3-D tracer, and numerically controlled machines. However, burrs and buckling of cell walls present a difficult problem for surface accuracy. It is clear that the machining of composite cores requires more expensive and sophisticated systems. This study illustrates a new strategy to fabricate arbitrary cross-section honeycomb cores with applications of advanced composite materials. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. The basic idea originates from the fold-made paper honeycombs proposed by authors, in which they attempted to apply origami and kirigami techniques to the creation of sandwich structures. Origami is the traditional Japanese art of paper folding. Kirigami is a variation of origami. We first introduce the concept of the origami honeycomb, which is made from single flat sheets with periodical slits resembling origami. In previous studies, honeycombs having various shapes were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D origami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs. Next, we describe a method of applying this technique to advanced composite materials. For partially soft composites, folding lines are materialized by silicon rubber hinges on carbon fiber reinforced plastic. Complex FLD patterns are then printed using masks on carbon fabrics. Finally, these foldable composites that are cured in corrugated shapes in autoclaves are folded into honeycomb shapes, and some typical samples are shown with their FLDs.", "date": "2013-08", "date_type": "published", "id_number": "CaltechAUTHORS:20130919-145814478", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130919-145814478", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Japan Society for the Promotion of Science (JSPS)", "grant_number": "19-5987" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.1115/DETC2013-12743", "primary_object": { "basename": "DETC2013-12743.pdf", "url": "https://authors.library.caltech.edu/records/v16ve-vax43/files/DETC2013-12743.pdf" }, "pub_year": "2013", "author_list": "Saito, Kazuya; Pellegrino, Sergio; et el." }, { "id": "https://authors.library.caltech.edu/records/50a1h-7r695", "eprint_id": 54737, "eprint_status": "archive", "datestamp": "2023-08-19 20:17:08", "lastmod": "2023-10-20 20:10:16", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Luhar-M", "name": { "family": "Luhar", "given": "M." } }, { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "A. S." }, "orcid": "0000-0002-7170-1627" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "A systems approach to modeling opposition control in turbulent pipe flow", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 AIAA. \n\nFinancial support from the AFOSR under award FA9550-12-1-0469 (program manager Doug Smith) is gratefully acknowledged (ML, BJM).", "abstract": "Despite being one of the earliest - and most studied - active control techniques proposed for wall-bounded turbulent flows, the opposition control method of Choi et al., [J.Fluid Mech., Vol. 262, 1994, pp. 75-110] remains to be fully understood. In this paper, we develop a simple model for opposition control by extending the forcing-response analysis presented in McKeon and Sharma [J. Fluid Mech., Vol. 658, 2010, pp. 336-382]. Based on a gain analysis of the Navier-Stokes equations, the velocity field in turbulent pipe flow is decomposed into a series of highly-amplified response modes (i.e., propagating helical\nwaves). Opposition control, introduced via the boundary condition on wall-normal velocity, alters the amplification characteristics and structure of these response modes, whereby a reduction in gain (mode suppression) leads to a reduction in drag. With simple assumptions, and minimal computation, our model reproduces the leading-order integrated effects of opposition control predicted by DNS. By breaking down opposition control into modal\nsubsystems, our analysis provides new physical insight into the deterioration of control performance with increasing sensor elevation and Reynolds number. We show that opposition control is only effective for specific wavenumber-frequency combinations; others require the introduction of a phase lag between sensed and actuated velocity. Moving forward, this mode-by-mode approach can enable the design and evaluation of targeted control techniques, as well as the definition of a theoretical limit for controller performance.", "date": "2013-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150211-141351820", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-141351820", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0469" } ] }, "other_numbering_system": { "items": [ { "id": "2013-2481", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2013-2481", "pub_year": "2013", "author_list": "Luhar, M.; Sharma, A. S.; et el." }, { "id": "https://authors.library.caltech.edu/records/2hsw0-afr39", "eprint_id": 54935, "eprint_status": "archive", "datestamp": "2023-08-19 20:17:16", "lastmod": "2023-10-20 20:35:41", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moarref-R", "name": { "family": "Moarref", "given": "Rashad" } }, { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "Ati S." }, "orcid": "0000-0002-7170-1627" }, { "id": "Tropp-J-A", "name": { "family": "Tropp", "given": "Joel A." }, "orcid": "0000-0003-1024-1791" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "Beverley J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "On effectiveness of a rank-1 model of turbulent channels for representing the velocity spectra", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2013 AIAA. \n\nThe support of Air Force Office of Scientific Research under grants FA 9550-09-1-0701 (P.M. John Schmisseur) and FA 9550-12-1-0469 (P.M. Doug Smith) is gratefully acknowledged.", "abstract": "We evaluate the efficacy of a gain-based rank-1 model, developed by McKeon & Sharma (J. Fluid Mech., 2010), for representing the energy spectra and the streamwise/wall-normal co-spectrum in a turbulent channel. This is motivated by our previous observation that the streamwise turbulent energy intensity is well approximated by the rank-1 model subject to a broadband forcing in the wall-parallel directions and a properly selected temporal intensity. In the present study, the evaluation is based on finding the optimal forcing spectrum that\nminimizes the deviation between the two-dimensional velocity spectra at different wall-normal locations obtained from direct numerical simulations at friction Reynolds number\n2003 (Hoyas & Jimin\u00e9nez, Phys. Fluids, 2006) and from the rank-1 model at equal Reynolds number. It is shown that the optimally forced rank-1 model captures the streamwise\nenergy spectrum for streamwise wavelengths smaller than approximately 1000 viscous units throughout the channel. For larger wavelengths, the streamwise spectrum is matched in the outer region of the channel, i.e. wall-normal distances larger than approximately 0.15 times the channel half-height, and the mismatch close to the wall results in less than 5 percent error in the inner-scaled peak of the streamwise energy intensity. In addition, we show that the rank-1 model with optimal forcing captures the essential features of the wall-normal and spanwise spectra and the streamwise/wall-normal co-spectrum. We observe that the predicted magnitudes of the latter three spectra are smaller in the rank-1 model compared to the simulation results suggesting that a higher-order or different rank-1 model may be necessary for accurate representation of these spectra.", "date": "2013-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150218-094025300", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150218-094025300", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-09-1-0701" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-12-1-0469" } ] }, "other_numbering_system": { "items": [ { "id": "2013-2480", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2013-2480", "pub_year": "2013", "author_list": "Moarref, Rashad; Sharma, Ati S.; et el." }, { "id": "https://authors.library.caltech.edu/records/gf5jv-0q619", "eprint_id": 54713, "eprint_status": "archive", "datestamp": "2023-08-19 20:17:01", "lastmod": "2023-10-20 20:08:36", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "A. S." }, "orcid": "0000-0002-7170-1627" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Closing the loop: an explicit calculation of the nonlinearity in the resolvent formulation of wall turbulence", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2013 AIAA. \n\nBJM gratefully acknowledges the support of NSF CAREER award grant number 0747672 (program managers William Schultz and H. Henning Winter) and the Air Force Office of Scientific Research (program manager John Schmisseur), grant number FA9550-09-1-0701.", "abstract": "The resolvent-based analysis of wall turbulence (McKeon & Sharma 2010) is extended with an explicit treatment of the non-linearity in the Navier-Stokes equations.\nThe equivalent of triadic interaction in the wall-normal direction is described, and it is found that the resulting forcing has a phase shift of \u03c0/2 in terms associated with symmetric spatial directions. Explicit forms for the nonlinearity in fully-developed pipe and channel \nflows, i.e. in cylindrical and Cartesian coordinate systems.", "date": "2013-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150211-102550604", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150211-102550604", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-0747672" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-09-1-0701" } ] }, "other_numbering_system": { "items": [ { "id": "2013-3118", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2013-3118", "pub_year": "2013", "author_list": "Sharma, A. S. and McKeon, B. J." }, { "id": "https://authors.library.caltech.edu/records/hne5z-85q52", "eprint_id": 97128, "eprint_status": "archive", "datestamp": "2023-08-19 12:39:24", "lastmod": "2023-10-20 21:58:31", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Regele-J-D", "name": { "family": "Regele", "given": "J. D." } }, { "id": "Rabinovitch-J", "name": { "family": "Rabinovitch", "given": "J." }, "orcid": "0000-0002-1914-7964" }, { "id": "Colonius-T", "name": { "family": "Colonius", "given": "T." }, "orcid": "0000-0003-0326-3909" }, { "id": "Blanquart-G", "name": { "family": "Blanquart", "given": "G." }, "orcid": "0000-0002-5074-9728" } ] }, "title": "Numerical Modeling and Analysis of Early Shock Wave Interactions with a Dense Particle Cloud", "ispublished": "unpub", "full_text_status": "public", "keywords": "Fluid Dynamics", "note": "\u00a9 2012 by Jonathan Regele. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. \n\nPublished Online: 6 Sep 2012. \n\nThe authors would like to thank Karen Oren for her contribution to this work.\n\nPublished - RegeleRabinovitchColoniusEtAl2012.pdf
", "abstract": "Dense compressible multiphase flows exist in variable phase turbines, explosions, and fluidized beds, where the particle volume fraction is in the range 0.001 < \u03b1_d < 0.5. A simple model problem that can be used to study modeling issues related to these types of flows is a shock wave impacting a particle cloud. In order to characterize the initial shock-particle interactions when there is little particle movement, a two-dimensional (2-D) model problem is created where the particles are frozen in place. Qualitative comparison with experimental data indicates that the 2-D model captures the essential flow physics. Volume-averaging of the 2-D data is used to reduce the data to one dimension, and x-t diagrams are used to characterize the flow behavior. An equivalent one-dimensional (1-D) model problem is developed for direct comparison with the 2-D model. While the 1-D model characterizes the overall steady-state flow behavior well, it fails to capture aspects of the unsteady behavior. As might be expected, it is found that neglecting the unclosed fluctuation terms inherent in the volume-averaged equations is not appropriate for dense gas-particle flows.", "date": "2012-09-06", "date_type": "published", "publisher": "American Institute of Aeronautics and Astronautics", "id_number": "CaltechAUTHORS:20190712-112323497", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190712-112323497", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2012-3161", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2012-3161", "primary_object": { "basename": "RegeleRabinovitchColoniusEtAl2012.pdf", "url": "https://authors.library.caltech.edu/records/hne5z-85q52/files/RegeleRabinovitchColoniusEtAl2012.pdf" }, "pub_year": "2012", "author_list": "Regele, J. D.; Rabinovitch, J.; et el." }, { "id": "https://authors.library.caltech.edu/records/9mnz8-y5059", "eprint_id": 28549, "eprint_status": "archive", "datestamp": "2023-08-19 02:24:44", "lastmod": "2023-10-24 17:58:44", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ando-Keita", "name": { "family": "Ando", "given": "K." } }, { "id": "Sanada-T", "name": { "family": "Sanada", "given": "T." } }, { "id": "Inaba-Kazuaki", "name": { "family": "Inaba", "given": "K." } }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "J. E." }, "orcid": "0000-0003-3181-9310" }, { "id": "Colonius-T", "name": { "family": "Colonius", "given": "T." }, "orcid": "0000-0003-0326-3909" }, { "id": "Brennen-C-E", "name": { "family": "Brennen", "given": "C. E." } } ] }, "title": "Shock Theory of a Bubbly Liquid in a Deformable Tube", "ispublished": "unpub", "full_text_status": "public", "keywords": "Fluid-structure interaction, bubbly water hammer", "note": "The authors would like to express their thanks to\nT. Nishiyama for his help with the experimentation, J. S.\nDamazo and R. Porowski for the bubble images, and\nS. Hori for his observations about the experimental data.\nThis work was supported by ONR Grant No. N00014-06-1-0730.\n\nAccepted Version - AndoSISCB-ICMF2010.pdf
", "abstract": "Shock propagation through a bubbly liquid filled in a deformable cylindrical tube is considered. Quasi-one-dimensional\nbubbly flow equations that include fluid-structure interaction are formulated, and the steady shock\nrelations are derived. Experiments are conducted in which a free-falling steel projectile impacts the top of an air/water\nmixture in a polycarbonate tube, and stress waves in the tube material are measured. The experimental data indicate\nthat the linear theory cannot properly predict the propagation speeds of shock waves in mixture-filled tubes; the shock\ntheory is found to more accurately estimate the measured wave speeds.", "date": "2011-12-21", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20111221-123516479", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111221-123516479", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-06-1-0730" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "primary_object": { "basename": "AndoSISCB-ICMF2010.pdf", "url": "https://authors.library.caltech.edu/records/9mnz8-y5059/files/AndoSISCB-ICMF2010.pdf" }, "pub_year": "2011", "author_list": "Ando, K.; Sanada, T.; et el." }, { "id": "https://authors.library.caltech.edu/records/g7zyn-rp921", "eprint_id": 41403, "eprint_status": "archive", "datestamp": "2023-08-19 07:37:44", "lastmod": "2023-10-24 23:42:28", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Aria-A-I", "name": { "family": "Aria", "given": "Adrianus I." } }, { "id": "Guittet-M", "name": { "family": "Guittet", "given": "M\u00e9lanie" } }, { "id": "Gharib-M", "name": { "family": "Gharib", "given": "Morteza" } } ] }, "title": "Effect of oxygen-containing functional groups on specific capacitance of carbon nanotube electrochemical capacitors", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2011 American Chemical Society.", "abstract": "Electrochem. capacitors have numerous applications, ranging from large scale hybrid vehicles to small scale consumer\nelectronics, with very high power d. at the cost of relatively low energy storage. A lot of works have been devoted to increase\npower and energy capacity as well as lifetime of such capacitors, and the use of functionalized carbon nanotube array is\nconsidered the most visible way to achieve that. We report here an approach to increase the specific capacitance of an\nelectrochem. capacitor by simply increasing the no. of oxygenated functional groups that are attached to the carbon nanotubes.\nThis finding shows an augmentation of nearly five orders of magnitude in the specific capacitance when the oxidn. level (oxygen\n/carbon at. ratio) of the nanotubes is increased from 2.5% to 7.5%. While this behavior was assessed in an aq. potassium\nhydroxide electrolyte, the totally opposite behavior with non polar and/or aprotic solvent is expected.", "date": "2011-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20130918-153901066", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130918-153901066", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "GALCIT" } ] }, "pub_year": "2011", "author_list": "Aria, Adrianus I.; Guittet, M\u00e9lanie; et el." }, { "id": "https://authors.library.caltech.edu/records/n1a1s-5b703", "eprint_id": 55248, "eprint_status": "archive", "datestamp": "2023-08-19 02:43:30", "lastmod": "2023-10-20 22:00:53", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "LeHew-J", "name": { "family": "LeHew", "given": "J." } }, { "id": "Guala-M", "name": { "family": "Guala", "given": "M." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "A study of convection velocities in a zero pressure gradient turbulent boundary layer", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 AIAA. \n\nThe support provided for this project by the Air Force Office of Scientific Research (program manager John Schmisseur) under award #FA9550-09-1-0701 is gratefully acknowledged.\n\nPublished - AIAA-2010-4474-356.pdf
", "abstract": "Time-resolved DPIV measurements performed in wall parallel planes at several wall normal locations in a turbulent boundary layer (TBL) are used to illuminate the distribution of wall parallel velocities in a three-dimensional energy spectrum over streamwise,\nspanwise, and temporal wavelengths. To our knowledge, this is the first time this type of spectral distribution has been reported. Slices of the 3D spectrum can give insight into the propagation of different scales in the \now as well as the streamwise and spanwise extent of\ndominant scales. Measurements were performed at three wall normal locations, y^+ = 34; 108; and 278, in a zero pressure gradient TBL at Re_\u03c4 = 470 . Two high speed cameras placed\nside-by-side in the streamwise direction give a 10\u03b4 streamwise field of view with a time step\nof \u0394t^+ = 0:5 between consecutive fields. Far from the wall the convection velocities of all scales are very close to the local mean velocity in agreement with the work of Dennis and Nickels, while at y^+ = 34 it was found that all measured scales in the flow convect faster\nthan the local mean in agreement with Krogstad et. al. The variation of the convection velocity with scale and distance from the wall will be discussed.", "date": "2010-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150226-100222113", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150226-100222113", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-09-1-0701" } ] }, "other_numbering_system": { "items": [ { "id": "2010-4474", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2010-4474", "primary_object": { "basename": "AIAA-2010-4474-356.pdf", "url": "https://authors.library.caltech.edu/records/n1a1s-5b703/files/AIAA-2010-4474-356.pdf" }, "pub_year": "2010", "author_list": "LeHew, J.; Guala, M.; et el." }, { "id": "https://authors.library.caltech.edu/records/46kc1-gs513", "eprint_id": 55244, "eprint_status": "archive", "datestamp": "2023-08-19 02:43:25", "lastmod": "2023-10-20 22:00:31", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jacobi-I", "name": { "family": "Jacobi", "given": "I." } }, { "id": "Guala-M", "name": { "family": "Guala", "given": "M." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Characteristics of a turbulent boundary layer perturbed by spatially-impulsive dynamic roughness", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 The Authors. \n\nThis work is supported by the Air Force Office of Scientific Research Hypersonics and Turbulence portfolio, under grant #FA9550-08-1-0049 (Program manager John Schmisseur).\n\nPublished - AIAA-2010-4475-378.pdf
", "abstract": "Statistical and spectral analyses of the manipulation of a canonical zero pressure gradient turbulent boundary layer using static roughness and low-frequency dynamic roughness patches are presented. A shift of spectral energy away from the wall downstream of the roughness patch is observed. The dynamic roughness is shown to disrupt the structure of the boundary layer, while embedding its periodic signature in an extensive stretch of the downstream flow field.", "date": "2010-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150226-094906075", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150226-094906075", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-08-1-0049" } ] }, "other_numbering_system": { "items": [ { "id": "2010-4475", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2010-4475", "primary_object": { "basename": "AIAA-2010-4475-378.pdf", "url": "https://authors.library.caltech.edu/records/46kc1-gs513/files/AIAA-2010-4475-378.pdf" }, "pub_year": "2010", "author_list": "Jacobi, I.; Guala, M.; et el." }, { "id": "https://authors.library.caltech.edu/records/5qemq-v7f69", "eprint_id": 22459, "eprint_status": "archive", "datestamp": "2023-08-19 02:06:30", "lastmod": "2023-10-23 16:03:10", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Deng-X", "name": { "family": "Deng", "given": "X." } }, { "id": "Pellegrino-S", "name": { "family": "Pellegrino", "given": "S." }, "orcid": "0000-0001-9373-3278" } ] }, "title": "Wrinkling of Orthotropic Viscoelastic Membranes", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 by X. Deng and S. Pellegrino. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.\n\nWe thank the NASA Super-Pressure Balloon team for their contributions to this research. In particular,\nDr Loren Seely (Aerostar International) has provided film samples, Dr David Wakefield (Tensys Dynamics\nLtd) and Dr Jim Rand (Winzen Engineering, Inc.) have helped with many comments. This research was\nsupported by the NASA Balloon Program Office (contract monitor Danny Ball).\n\nPublished - Deng_AIAA_2010_2670.pdf
", "abstract": "This paper presents a simplified simulation technique for orthotropic viscoelastic films.\nWrinkling is detected by a combined stress-strain criterion and an iterative scheme searches\nfor the wrinkle angle using a pseudo-elastic material stiffness matrix based on a nonlinear\nviscoelastic constitutive model. This simplified model has been implemented in\nABAQUS/Explicit and is able to compute the behavior of a membrane structure by superposition\nof a small number of response increments. The model has been tested against\na published solution for a time-independent isotropic membrane under simple shear and\nalso against experimental results on StratoFilm 420 under simple shear.", "date": "2010-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20110223-131222888", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110223-131222888", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA" } ] }, "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "AIAA-2010-2670", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT", "value": "GALCIT" } ] }, "primary_object": { "basename": "Deng_AIAA_2010_2670.pdf", "url": "https://authors.library.caltech.edu/records/5qemq-v7f69/files/Deng_AIAA_2010_2670.pdf" }, "pub_year": "2010", "author_list": "Deng, X. and Pellegrino, S." }, { "id": "https://authors.library.caltech.edu/records/ex1yj-gbs30", "eprint_id": 55464, "eprint_status": "archive", "datestamp": "2023-08-19 01:19:05", "lastmod": "2023-10-20 22:16:27", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Drake-A", "name": { "family": "Drake", "given": "Aaron" } }, { "id": "Bender-A-M", "name": { "family": "Bender", "given": "Anne M." } }, { "id": "Korntheuer-A-J", "name": { "family": "Korntheuer", "given": "Andrea J." } }, { "id": "Westphal-R-V", "name": { "family": "Westphal", "given": "Russell V." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "Beverley J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Gerashchenko-S", "name": { "family": "Gerashchenko", "given": "Sergiy" } }, { "id": "Rohe-W", "name": { "family": "Rohe", "given": "Wayne" } }, { "id": "Dale-G", "name": { "family": "Dale", "given": "Gary" } } ] }, "title": "Step Excrescence Effects for Manufacturing Tolerances on Laminar Flow Wings", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 Northrop Grumman. \n\nThis work was sponsored by the U.S. Air Force Research Laboratory, Air Vehicles Directorate.\n\nPublished - AIAA-2010-375-907.pdf
", "abstract": "Manufacturing tolerances for laminar flow wings can be significantly tighter than those of conventional aircraft. The tighter tolerances can significantly affect the assessment of the practicality of designing for laminar flow. However, existing data on the effects of excrescences typical of manufacturing process are limited. Further, information on the effects\u2014often beneficial\u2014of pressure gradient present on the laminar flow wings is not generally available. To address these concerns, a series of experiments has been undertaken to examine the effects of surface steps in the presence of pressure gradients. The step geometries were selected to represent those that result from actual aircraft manufacturing processes. The range of pressure gradients correspond to those typical of laminar flow wings. Initial experiments were conducted in a low-speed wind tunnel. Later experiments used a novel propelled-model test facility. The results of these studies show that the allowable sizes of surface excrescences for laminar flow wings may be significantly greater than has conventionally been assumed. This could significantly influence the more widespread use of laminar flow for drag reduction, resulting in more efficient aircraft.", "date": "2010-01", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-110715680", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-110715680", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Research Laboratory" } ] }, "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "2010-375", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT", "value": "GALCIT" } ] }, "doi": "10.2514/6.2010-375", "primary_object": { "basename": "AIAA-2010-375-907.pdf", "url": "https://authors.library.caltech.edu/records/ex1yj-gbs30/files/AIAA-2010-375-907.pdf" }, "pub_year": "2010", "author_list": "Drake, Aaron; Bender, Anne M.; et el." }, { "id": "https://authors.library.caltech.edu/records/adkbm-dsg45", "eprint_id": 55468, "eprint_status": "archive", "datestamp": "2023-08-19 01:19:15", "lastmod": "2023-10-20 22:16:39", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bender-A-M", "name": { "family": "Bender", "given": "Anne M." } }, { "id": "Elliott-J-R", "name": { "family": "Elliott", "given": "J. Russell" } }, { "id": "Shinagawa-Yuto", "name": { "family": "Shinagawa", "given": "Yuto" } }, { "id": "Korntheuer-A-J", "name": { "family": "Korntheuer", "given": "Andrea J." } }, { "id": "Drake-A", "name": { "family": "Drake", "given": "Aaron" } }, { "id": "Westphal-R-V", "name": { "family": "Westphal", "given": "Russell V." } }, { "id": "Gerashchenko-S", "name": { "family": "Gerashchenko", "given": "Sergiy" } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Yoshioka-Shuya", "name": { "family": "Yoshioka", "given": "Shuya" } } ] }, "title": "An Approach to Measuring Step Excrescence Effects in the Presence of a Pressure Gradient", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 Northrop Grumman. \n\nThis work was sponsored by the U.S. Air Force Research Laboratory, Air Vehicles Directorate. \n\nThe contributions of Mr. Donald Frame and Mr. Steven Jordan to the development of the boundary layer data system are gratefully acknowledged.\n\nPublished - AIAA-2010-373-821.pdf
", "abstract": "An experimental study was undertaken to determine the effects of step excrescences on boundary layer transition using a unique ground test facility in which the test model was propelled though still air. The models used were designed to have a nominally constant pressure gradient so that the results would be relevant to laminar flow aircraft whose wings often have long runs of mildly favorable pressure gradient. The models had an integrated continuously adjustable two-dimensional step, which could be adjusted to be forward-facing or aft-facing. The large model was used to increase the Reynolds numbers examined so that the results are applicable to laminar flow flight vehicles. Multiple measurement methods, including Preston tubes, hot wires, accelerometers, a boundary layer traverse, and static pressure taps were used to provide comparison data, and to add to the physical understanding of the results. The propelled-model test approach required that the instrumentation be self-contained and ride along with the model as the carrier vehicle moved down the test track. Due to the relatively short times available for data-taking (approximately 15-30 seconds per run), the initialization and data analysis techniques had to be tailored for this application.", "date": "2010-01", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-112035324", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-112035324", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Research Laboratory" } ] }, "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "2010-373", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT", "value": "GALCIT" } ] }, "doi": "10.2514/6.2010-373", "primary_object": { "basename": "AIAA-2010-373-821.pdf", "url": "https://authors.library.caltech.edu/records/adkbm-dsg45/files/AIAA-2010-373-821.pdf" }, "pub_year": "2010", "author_list": "Bender, Anne M.; Elliott, J. Russell; et el." }, { "id": "https://authors.library.caltech.edu/records/e9n96-j4b19", "eprint_id": 55466, "eprint_status": "archive", "datestamp": "2023-08-19 01:19:09", "lastmod": "2023-10-20 22:16:33", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gerashchenko-S", "name": { "family": "Gerashchenko", "given": "S." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Westphal-R-V", "name": { "family": "Westphal", "given": "R. V." } }, { "id": "Bender-A-M", "name": { "family": "Bender", "given": "A. M." } }, { "id": "Drake-A", "name": { "family": "Drake", "given": "A." } } ] }, "title": "Hot-Wire Measurements of the Influence of Surface Steps on Transition in Favorable Pressure Gradient Boundary Layers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 Northrop Grumman. \n\nThe authors acknowledge funding and support from the Air Force Research Laboratory, Prof. Mike Gaster of Queen Mary College, University of London, for the use of the Rapid-N code, and Prof. Bill Saric for useful advice.\n\nPublished - AIAA-2010-374.pdf
", "abstract": "An examination of the effects of surface step excrescences on boundary layer transition was performed, using a unique experimental facility. The objective of the work was to characterize the variation of transition Reynolds numbers with measurable step size and boundary layer parameters, with the specific goal of specifying new tolerance criteria for laminar flow airfoils, alongside a fundamental investigation of boundary layer transition mechanisms. This paper focuses on interpretation of hot-wire measurements, including supporting stability calculations, undertaken as part of the study. The results for both forward and aft-facing steps indicated a substantial stabilizing effect of favorable pressure gradient on excrescence-induced boundary layer transition. These findings suggest that manufacturing tolerances for laminar flow aircraft could be loosened in areas where even mild favorable pressure gradients exist.", "date": "2010-01", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-111551041", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-111551041", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Research Laboratory" } ] }, "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "2010-374", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT", "value": "GALCIT" } ] }, "doi": "10.2514/6.2010-374", "primary_object": { "basename": "AIAA-2010-374.pdf", "url": "https://authors.library.caltech.edu/records/e9n96-j4b19/files/AIAA-2010-374.pdf" }, "pub_year": "2010", "author_list": "Gerashchenko, S.; McKeon, B. J.; et el." }, { "id": "https://authors.library.caltech.edu/records/qazvz-3vq34", "eprint_id": 55462, "eprint_status": "archive", "datestamp": "2023-08-19 01:19:00", "lastmod": "2023-10-20 22:16:21", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "A. S." }, "orcid": "0000-0002-7170-1627" } ] }, "title": "Energetic Modes in Turbulent Pipe Flow From Resolvent Analysis", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2010 McKeon and Sharma. \n\nThe support of NSF CAREER award grant number 0747672 (program managers William Schultz and H. Henning Winter), Air Force Office of Scientific Research (program manager John Schmisseur), grant number FA9550-09-1-0701 (B.J.M.), an Imperial College Junior Research Fellowship and the EPSRC (A.S.) is gratefully acknowledged. We would also like to thank A. Meseguer and L. Trefethen for publishing their pipe code.\n\nPublished - AIAA-2010-697.pdf
", "abstract": "We describe a method to investigate the mode shapes in turbulent pipe flow at a given\nwavenumber pair that are most responsive to harmonic forcing in the sense that the they\ncorrespond to the largest singular value in a Schmidt decomposition of the linear Navier-Stokes operator using the turbulent mean profile as the base flow. The ideas follow logically\nfrom the work of Sharma & McKeon (2009), who considered a similar approach for laminar pipe flow.", "date": "2010-01", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-105749150", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-105749150", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-0747672" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-09-1-0701" }, { "agency": "Imperial College London" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)" } ] }, "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "2010-697", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT", "value": "GALCIT" } ] }, "doi": "10.2514/6.2010-697", "primary_object": { "basename": "AIAA-2010-697.pdf", "url": "https://authors.library.caltech.edu/records/qazvz-3vq34/files/AIAA-2010-697.pdf" }, "pub_year": "2010", "author_list": "McKeon, B. J. and Sharma, A. S." }, { "id": "https://authors.library.caltech.edu/records/qd6xv-m7p56", "eprint_id": 55470, "eprint_status": "archive", "datestamp": "2023-08-20 01:54:04", "lastmod": "2023-10-20 22:16:45", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Jacobi-I", "name": { "family": "Jacobi", "given": "I." } }, { "id": "LeHew-J", "name": { "family": "LeHew", "given": "J." } } ] }, "title": "Perturbation of a turbulent boundary layer by spatially-impulsive dynamic roughness", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 by B. J. McKeon, I. Jacobi & J. LeHew. \n\nThe support of the Air Force Office of Scientific Research Boundary Layer Physics program under award #FA9550-08-1-0049 (program manager: John Schmisseur) is gratefully acknowledged.\n\nPublished - AIAA-2009-3566-371.pdf
", "abstract": "First experimental measurements of manipulation of the structure of a canonical zero pressure gradient\nturbulent boundary layer using a low frequency (compared to the viscous frequency) mechanical dynamic\nroughness are presented. \"Dynamic\" (or time-dependent) surface roughness is proposed as a method for both\ncontrol and diagnosis of turbulent boundary layers.", "date": "2009-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-113157017", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-113157017", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-08-1-0049" } ] }, "other_numbering_system": { "items": [ { "id": "2009-3566", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2009-3566", "primary_object": { "basename": "AIAA-2009-3566-371.pdf", "url": "https://authors.library.caltech.edu/records/qd6xv-m7p56/files/AIAA-2009-3566-371.pdf" }, "pub_year": "2009", "author_list": "McKeon, B. J.; Jacobi, I.; et el." }, { "id": "https://authors.library.caltech.edu/records/dqg07-kz333", "eprint_id": 55469, "eprint_status": "archive", "datestamp": "2023-08-20 01:53:59", "lastmod": "2023-10-20 22:16:42", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Norman-A-K", "name": { "family": "Norman", "given": "A. K." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Forces on a Sphere in the Presence of Static and Dynamic Roughness Elements", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 by AK Norman and BJ McKeon. \n\nSupport from the National Science Foundation under Grant No. 0747672 (Program Manager William W. Schultz) is gratefully acknowledged.\n\nPublished - AIAA-2009-3704-805.pdf
", "abstract": "Though the effect of distributed roughness on \nflow over a sphere has been examined in detail, there have been few observations as to the effect of an isolated roughness element on the forces induced on a sphere that is in uniform flow. In this experimental study, we\nexamine how the forces are altered due to both a stationary and dynamic three-dimensional roughness element in the Reynolds number range of 5 x 104 to 5 x 105. It is found that even a small change to the geometry of the sphere, by adding a cylindrical roughness element with a width and height of 1% the sphere diameter, dramatically alters the drag and lateral forces over a wide range of Reynolds numbers. Of particular interest is that the mean of\nthe lateral force magnitude can be increased by a factor of about seven, compared with a stationary stud, by moving the isolated roughness at a constant angular velocity about\nthe sphere. These results can be applied to tripping a laminar boundary layer, steering a bluff body, and increasing the mixing of two fluids, using a minimal amount of energy input. This research is a first step towards understanding the interaction between time dependent surface motion and the subsequent alteration of the location of the boundary layer separation line and wake development.", "date": "2009-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-112614795", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-112614795", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "CBET-0747672" } ] }, "other_numbering_system": { "items": [ { "id": "2009-3704", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2009-3704", "primary_object": { "basename": "AIAA-2009-3704-805.pdf", "url": "https://authors.library.caltech.edu/records/dqg07-kz333/files/AIAA-2009-3704-805.pdf" }, "pub_year": "2009", "author_list": "Norman, A. K. and McKeon, B. J." }, { "id": "https://authors.library.caltech.edu/records/htyw6-cy827", "eprint_id": 51439, "eprint_status": "archive", "datestamp": "2023-08-20 00:40:17", "lastmod": "2023-10-18 16:29:01", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "A. S." }, "orcid": "0000-0002-7170-1627" }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Perturbation Energy Production in Pipe Flow over a Range of Reynolds Numbers using Resolvent Analysis", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2009 AIAA. \n\nThe support of the UK EPSRC and an NSF-CAREER award No. 0747672 (Program Manager William W. Schultz) are gratefully acknowledged by A. Sharma and B. McKeon, respectively.\n\nPublished - Sharma-AIAA-2009-1513.pdf
", "abstract": "The response of pipe flow to physically realistic, temporally and spatially continuous(periodic) forcing is investigated by decomposing the resolvent into orthogonal forcing and response pairs ranked according to their contribution to the resolvent 2-norm. Modelling the non-linear terms normally neglected by linearisation as unstructured forcing permits qualitative extrapolation of the resolvent norm results beyond infinitesimally small perturbations to the turbulent case. The concepts arising have a close relationship to input output transfer function analysis methods known in the control systems literature. The body forcings that yield highest disturbance energy gain are identified and ranked by the decomposition and a worst-case bound put on the energy gain integrated across the pipe cross-section. Analysis of the spectral variation of the corresponding response modes reveals interesting comparisons with recent observations of the behavior of the streamwise velocity in high Reynolds number (turbulent) pipe flow, including the importance of very long scales of the order of ten pipe radii, in the extraction of turbulent energy from the mean flow by the action of turbulent shear stress against the velocity gradient.", "date": "2009-01-05", "date_type": "published", "id_number": "CaltechAUTHORS:20141107-113657314", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-113657314", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Engineering and Physical Sciences Research Council (EPSRC)" }, { "agency": "NSF", "grant_number": "CBET-0747672" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2013-3118", "primary_object": { "basename": "Sharma-AIAA-2009-1513.pdf", "url": "https://authors.library.caltech.edu/records/htyw6-cy827/files/Sharma-AIAA-2009-1513.pdf" }, "pub_year": "2009", "author_list": "Sharma, A. S. and McKeon, B. J." }, { "id": "https://authors.library.caltech.edu/records/meac6-8ya87", "eprint_id": 55472, "eprint_status": "archive", "datestamp": "2023-08-19 22:49:59", "lastmod": "2023-10-20 22:16:52", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Norman-A-K", "name": { "family": "Norman", "given": "A. K." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Effect of sting size on the wake of a sphere at subcritical Reynolds numbers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 AIAA. \n\nSupport from the National Science Foundation under Grant No. 0747672 (Program Manager William W. Schultz) is gratefully acknowledged.\n\nPublished - AIAA-2008-4183.pdf
", "abstract": "Vortex shedding and turbulent motion in the wake of a sphere that is supported using\na streamwise-aligned cylindrical sting are investigated at a subcritical Reynolds number of\nRe=3800, using high speed particle image velocimetry. The mechanism by which the presence of a sting of increasing diameter relative to the diameter of the sphere influences the wake, in terms of both the small-scale shear instability and the larger wake instability, is\nexplored and brie\ny compared with the two-dimensional analog of the splitter plate introduced into a cylinder wake. The difficulties associated with obtaining converged statistics,\nalong with the effect of free stream turbulence and sphere vibrations are detailed. An\nunderstanding of the mechanism by which the blockage, or interference, arising from the\npresence of the sting influences cross-wake communication and downstream development\nis a necessary precursor to studies of active control of the wake using surface actuation on\na sting-mounted sphere.", "date": "2008-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-113517097", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-113517097", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF CAREER", "grant_number": "0747672" } ] }, "other_numbering_system": { "items": [ { "id": "2008-4183", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.1021/ja508718m10.2514/6.2008-4183", "primary_object": { "basename": "AIAA-2008-4183.pdf", "url": "https://authors.library.caltech.edu/records/meac6-8ya87/files/AIAA-2008-4183.pdf" }, "pub_year": "2008", "author_list": "Norman, A. K. and McKeon, B. J." }, { "id": "https://authors.library.caltech.edu/records/xvz6z-bvr53", "eprint_id": 51443, "eprint_status": "archive", "datestamp": "2023-08-19 22:49:54", "lastmod": "2023-10-18 16:43:49", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" } ] }, "title": "Scaling in Wall Turbulence: Scale Separation and Interaction (Invited Paper)", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a92008 AIAA. \n\nThe support of the Office of Naval Research (Ron Joslin, Program Manager), for continuing investigation into scaling and scale interaction high Reynolds number flow is gratefully acknowledged. The author would like to thank Lex Smits and Jonathan Morrison for continuing use of data from the Princeton/ONR Superpipe and insightful conversations. It is a pleasure to acknowledge useful discussion with Michele Guala.\n\nPublished - AIAA-2008-4183__2_.pdf
", "abstract": "High Reynolds number pipe flow data are used to demonstrate the importance of several conditions related to scale separation that are either assumed in the classical theories\nor may be used in light of recent results in wall turbulence to infer a minimum Reynolds number condition above which scaling results may be suitable for extrapolation. Results from the Princeton Superpipe have suggested Re_\u03c4 > 5000 as the minimum Reynolds number\nfor which key properties of pipe flow reach a \"fully-developed\" condition, based on observations of streamwise mean and turbulent velocity structure. Additional values related to finer constraints on the structural development are also discussed. A \"skeleton\" of wall turbulence is introduced, based on structural components identified as having a dominant role in the dynamics of near-wall turbulence in recent experiments by a variety of authors.\nPossible interaction mechanisms between these components are described alongside some outstanding questions concerning scale separation and interaction.", "date": "2008-06", "date_type": "published", "id_number": "CaltechAUTHORS:20141107-121005176", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141107-121005176", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2008-4237", "primary_object": { "basename": "AIAA-2008-4183__2_.pdf", "url": "https://authors.library.caltech.edu/records/xvz6z-bvr53/files/AIAA-2008-4183__2_.pdf" }, "pub_year": "2008", "author_list": "McKeon, B. J." }, { "id": "https://authors.library.caltech.edu/records/cg208-t1q21", "eprint_id": 55475, "eprint_status": "archive", "datestamp": "2023-08-19 21:56:33", "lastmod": "2023-10-20 22:17:02", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Bender-A-M", "name": { "family": "Bender", "given": "A. M." } }, { "id": "Westphal-R-V", "name": { "family": "Westphal", "given": "R. V." } }, { "id": "Drake-A", "name": { "family": "Drake", "given": "A." } } ] }, "title": "Transition in incompressible boundary layers with two-dimensional excrescences", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2008 Northrop Grumman. \n\nThe authors would like to thank Lt. Jeff Komives and Dr. Carl Tilmann of the U.S. Air Force Research Laboratory for inspiring and motivating this work and Professor Mike Gaster at Queen Mary College, University of London, for the use of his Rapid-N code. Contributions to the data analysis by Kevin Chen and Christine Siew are also acknowledged.\n\nPublished - AIAA-2008-589-456.pdf
", "abstract": "An experimental investigation of the transition process in boundary layers subjected\nto forward- or aft-facing two-dimensional step excrescences is described. The objective of\nthe work was to characterize the variation of transition Reynolds numbers with measurable\nroughness and boundary layer parameters, with the specific goal of specifying new tolerance\ncriteria for laminar flow airfoils, alongside a fundamental investigation of linear boundary\nlayer stability mechanisms. Results from an ongoing program of increasing complexity on\neffects of pressure gradient on excrescence-induced transition are presented. Preliminary\nN-factor calculations are used to determine the effects of boundary layer stability and\nattempt to isolate the effect of the disturbance due to the excrescence.", "date": "2008-01", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-121020776", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-121020776", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "2008-589", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2008-589", "primary_object": { "basename": "AIAA-2008-589-456.pdf", "url": "https://authors.library.caltech.edu/records/cg208-t1q21/files/AIAA-2008-589-456.pdf" }, "pub_year": "2008", "author_list": "McKeon, B. J.; Bender, A. M.; et el." }, { "id": "https://authors.library.caltech.edu/records/2v4kn-j2146", "eprint_id": 55476, "eprint_status": "archive", "datestamp": "2023-08-19 17:55:50", "lastmod": "2023-10-20 22:17:06", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Sharma-A-S", "name": { "family": "Sharma", "given": "A. S." }, "orcid": "0000-0002-7170-1627" }, { "id": "Limebeer-D-J-N", "name": { "family": "Limebeer", "given": "D. J. N." } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "B. J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Morrison-J-F", "name": { "family": "Morrison", "given": "J. F." } } ] }, "title": "Stabilising Control Laws for the Incompressible Navier-Stokes Equations using Sector Stability Theory", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a92006 AIAA. \n\nA. Sharma, J. Morrison and D. Limebeer thank BAE systems and the UK EPSRC for their support under the FLAVIIR project. B. McKeon thanks the Royal Society for their support under a Dorothy Hodgkin Fellowship.\n\nPublished - AIAA-2006-3695-788.pdf
", "abstract": "A method for nonlinear global stabilisation of the incompressible Navier-Stokes equations\nis presented and used to eliminate transient growth in linearly stable Poiseuille flow\nfor the case of full-field actuation and sensing. In the absence of complete velocity field\nsensing and full actuation the controller synthesis procedure gives a controller that minimises\nthe the attainable perturbation energy over all disturbances and thus maximises the\ndisturbance threshold for transition to occur. The control laws are found using the theory\nof positive real systems, originating in the control systems community. It is found that a\ncontrol law making the linearised part of the perturbed Navier-Stokes equations positive\nreal, provides nonlinear global stability. A state-space synthesis procedure is presented\nthat results in two game-theoretic algebraic Riccati equations.", "date": "2006-06", "date_type": "published", "id_number": "CaltechAUTHORS:20150303-121446831", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150303-121446831", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "BAE Systems" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "FLAVIIR" }, { "agency": "Royal Society Dorothy Hodgkin Fellowship" } ] }, "other_numbering_system": { "items": [ { "id": "2006-3695", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.2006-3695", "primary_object": { "basename": "AIAA-2006-3695-788.pdf", "url": "https://authors.library.caltech.edu/records/2v4kn-j2146/files/AIAA-2006-3695-788.pdf" }, "pub_year": "2006", "author_list": "Sharma, A. S.; Limebeer, D. J. N.; et el." }, { "id": "https://authors.library.caltech.edu/records/7zkp6-wyx81", "eprint_id": 21873, "eprint_status": "archive", "datestamp": "2023-08-19 15:32:30", "lastmod": "2023-10-23 15:27:44", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kang-D-M", "name": { "family": "Kang", "given": "Dal Mo" } }, { "id": "Culick-F-E-C", "name": { "family": "Culick", "given": "F. E. C." } }, { "id": "Ratner-A", "name": { "family": "Ratner", "given": "Abert" } } ] }, "title": "An experimental study of coupling between combustor pressure, fuel/air mixing, and the flame", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 This work was supported in part by the California\nInstitute of Technology and partly by the Air Force Office\nof Scientific Research (AFOSR) under Grant No. F49620-\n03-1-0384 (Dr. Mitat Birkan, Program Manager).\nWe also acknowledge the assistance of Carlos Pinedo for\nthe experimental set-up.\n\nAccepted Version - Kang_DM_An_Experimental_study_of.pdf
", "abstract": "Fuel-air mixing behavior under the influence of imposed acoustic oscillations has been studied by investigating the response of the fuel mixture fraction field. The distribution of local fuel mixture fraction inside the mixing zone, which is expected to evolve into the local equivalence ratio in the flame zone, is closely coupled to unstable and oscillatory flame behavior. The Experiment was performed with an aerodynamically-stabilized non-premixed burner. In this study, acoustic oscillations were imposed at 22, 27, 32, 37, and 55Hz. Phase-resolved acetone PLIF was used to image the flow field of both isothermal and reacting flow cases and this data along with the derived quantities of temporal and spatial unmixedness were employed for analysis. The behavior of the unmixedness factor is compared with the previous measurements of oscillations in the flame zone. This comparison shows that local oscillations (of order millimeters or smaller) in fuel/air mixing are closely related to the oscillatory behavior of the flame. For each driving frequency, the mixture fraction oscillates at that frequency but with a slight phase difference between it and the pressure field/flame intensity, indicating that the fuel mixture fraction oscillation are likely the major reason for oscillatory behaviors of this category of flames and combustor geometry.", "date": "2005-03-22", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20110125-074002108", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110125-074002108", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "F49620-03-1-0384" } ] }, "other_numbering_system": { "items": [ { "name": "Guggenheim Jet Propulsion Center" } ] }, "local_group": { "items": [ { "id": "Guggenheim-Jet-Propulsion-Center" }, { "id": "GALCIT" } ] }, "primary_object": { "basename": "Kang_DM_An_Experimental_study_of.pdf", "url": "https://authors.library.caltech.edu/records/7zkp6-wyx81/files/Kang_DM_An_Experimental_study_of.pdf" }, "pub_year": "2005", "author_list": "Kang, Dal Mo; Culick, F. E. C.; et el." }, { "id": "https://authors.library.caltech.edu/records/d5t3m-n6y56", "eprint_id": 28206, "eprint_status": "archive", "datestamp": "2023-08-19 09:50:58", "lastmod": "2023-10-24 17:44:28", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hung-P", "name": { "family": "Hung", "given": "Patrick" } }, { "id": "Shepherd-J-E", "name": { "family": "Shepherd", "given": "Joseph" }, "orcid": "0000-0003-3181-9310" } ] }, "title": "Reduction of Detailed Chemical Reaction Networks for Detonation", "ispublished": "unpub", "full_text_status": "public", "note": "Also available in the Caltech Center for Simulation of the Dynamic Response in Materials archive, cit-asci-tr137, at http://csdrm.caltech.edu/publications/index.html", "abstract": "While a detailed mechanism represents the state-of-the-art of what\nis known about a reaction network, its direct implementation in a\nfully resolved CFD simulation is all but impossible (except for the\nsimplest systems) with the computational power available today.\nThis paper discusses the concept of Intrinsic Low Dimensional\nManifold (ILDM), a technique that systematically reduces the\ncomplexity of detailed mechanisms. The method, originally devel-oped\nfor combustion systems, has been successfully extended and\napplied to gaseous detonation simulations 2,3,4 . Unfortunately, while\na one-dimensional ILDM is reasonably easy to compute, manifolds\nof higher dimensions are notoriously difficult. Moreover, the selec-tion\nof the manifold dimension has been largely arbitrary, with a\none-dimensional ILDM being the most popular if for no other rea-son\nthan that it is easiest to compute and store.\nIn this paper, we will present a technique that enables us to quanti-tatively\ndetermine the dimensionality of the ILDM needed, as well\nas a robust and embarrassingly parallel algorithm for computing\nhigh-dimensional ILDMs. Finally, these techniques are demon-strated\nin the context of a one-dimensional ZND detonation with\ndetailed chemistry.", "date": "2002-08", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechCACR:2002.004", "official_url": "https://resolver.caltech.edu/CaltechCACR:2002.004", "rights": "You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format.", "local_group": { "items": [ { "id": "Center-for-Advanced-Computing-Research" }, { "id": "GALCIT" } ] }, "primary_object": { "basename": "HungDetSymp02.pdf", "url": "https://authors.library.caltech.edu/records/d5t3m-n6y56/files/HungDetSymp02.pdf" }, "pub_year": "2002", "author_list": "Hung, Patrick and Shepherd, Joseph" }, { "id": "https://authors.library.caltech.edu/records/f19zz-a5c13", "eprint_id": 55513, "eprint_status": "archive", "datestamp": "2023-08-19 08:51:48", "lastmod": "2023-10-20 22:19:22", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Morrison-J-F", "name": { "family": "Morrison", "given": "Jonathan F." } }, { "id": "Jiang-Weimin", "name": { "family": "Jiang", "given": "Weimin" } }, { "id": "McKeon-B-J", "name": { "family": "McKeon", "given": "Beverley J." }, "orcid": "0000-0003-4220-1583" }, { "id": "Smits-A-J", "name": { "family": "Smits", "given": "Alexander J." } } ] }, "title": "Reynolds-number Dependence of Streamwise Velocity Fluctuations in Turbulent Pipe Flow", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2002 AIAA. \n\nThe support of ONR under Grant Nos. N00014-98-1-0525 and N00014-99-1-0340 is gratefully acknowledged. JFM is indebted to both the Engineering and Physical Sciences Research Council (GR/M64536/01 and GR/R48193/01) and the Royal Academy of Engineering (England) for financial support.\n\nPublished - AIAA-2002-0574.pdf
", "abstract": "Statistics of the streamwise velocity component in fully-developed pipe flow are examined for Reynolds numbers in the range 5.5 x 10^4 < Re_D < 5.7 x 10^6. The second moment exhibits two maxima: one in the viscous sublayer is Reynolds-number dependent while the other, near the lower edge of the log region, is also Reynolds-number dependent and follows roughly the peak in Reynolds shear stress. The behaviour of both peaks is consistent with the concept of inactive motion which increases with increasing Reynolds number and decreasing distance from the wall. No simple scaling is apparent, and in particular, so-called \"mixed\" scaling is no better than wall scaling in the viscous sublayer and is actually worse than wall scaling in the outer region. The second moment is compared with empirical and theoretical scaling laws\nand some anomalies are apparent. The scaling of spectra using y, R and u_\u03c4 is examined. It appears that even at the highest Reynolds number, they exhibit\nincomplete similarity only: while spectra do collapse with either inner or outer scales for limited ranges of wave number, these ranges do not overlap. Thus similarity may not be described as complete and any apparent k_1^(-1) range does not attract any special significance and does not involve universal constants. It is suggested that this is because of the influence of inactive motion. Spectra also show the presence of very long structures close to the wall.", "date": "2002-01", "date_type": "published", "id_number": "CaltechAUTHORS:20150304-112212308", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150304-112212308", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-98-1-0525" }, { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-99-1-0340" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "GR/M64536/01" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "GR/R48193/01" }, { "agency": "Royal Academy of Engineering (England)" } ] }, "collection": "CaltechAUTHORS", "other_numbering_system": { "items": [ { "id": "2002-0574", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT", "value": "GALCIT" } ] }, "doi": "10.2514/6.2002-574", "primary_object": { "basename": "AIAA-2002-0574.pdf", "url": "https://authors.library.caltech.edu/records/f19zz-a5c13/files/AIAA-2002-0574.pdf" }, "pub_year": "2002", "author_list": "Morrison, Jonathan F.; Jiang, Weimin; et el." }, { "id": "https://authors.library.caltech.edu/records/x5356-4gx93", "eprint_id": 52559, "eprint_status": "archive", "datestamp": "2023-08-20 00:56:29", "lastmod": "2023-10-18 20:58:52", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Wissler-J-B", "name": { "family": "Wissler", "given": "John B." } }, { "id": "Roshko-A", "name": { "family": "Roshko", "given": "Anatol" } } ] }, "title": "Transmission of thin light beams through turbulent mixing layers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1992 AIAA. \n\nThis research was supported by the Air Force Office of Scientific Research and Phillips Laboratory under AFOSR Grant No. AFOSR-89-0552. We wish to thank Professors Donald Coles and Bradford Sturtevant for crucial suggestions for the experimental techniques.\n\nPublished - 388458.pdf
", "abstract": "This research investigates the effects of spanwise and streamwise coherent structures in a turbulent mixing layer on the deflection of a thin light beam which is transmitting transversely through the mixing layer from the high-speed side to the low speed side. Both equal and unequal density mixing layers of varying pressures and velocities are studied, using a lateral effect detector to dynamically track the motion of a He-Ne laser beam. Beam deflections in the streamwise direction are found to be associated mainly with the spanwise coherent structures; at low Reynolds Numbers the beam deflection is directly related to the part of a spanwise structure through which the beam passes. Maximum deflections are associated with the trailing edge of the spanwise coherent structures. Spanwise deflections are caused mainly by the streamwise coherent structures and as such exhibit large variations across the span of the flow. With the development of the streamwise structures, spanwise deflections are found to exceed streamwise deflections. Mixing transition, as scaled using the momentum thickness of the high-speed side, is found to cause a peak in therms fluctuations of both the streamwise and spanwise deflections.", "date": "1992-01", "date_type": "published", "id_number": "CaltechAUTHORS:20141210-134738343", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141210-134738343", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "AFOSR-89-0552" } ] }, "other_numbering_system": { "items": [ { "id": "92-0658", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1992-658", "primary_object": { "basename": "388458.pdf", "url": "https://authors.library.caltech.edu/records/x5356-4gx93/files/388458.pdf" }, "pub_year": "1992", "author_list": "Wissler, John B. and Roshko, Anatol" }, { "id": "https://authors.library.caltech.edu/records/9327t-n5e83", "eprint_id": 52558, "eprint_status": "archive", "datestamp": "2023-08-19 17:39:40", "lastmod": "2023-10-18 20:58:49", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roberts-F-A", "name": { "family": "Roberts", "given": "F. A." } }, { "id": "Roshko-A", "name": { "family": "Roshko", "given": "A." } } ] }, "title": "Effects of periodic forcing on mixing in turbulent shear layers and wakes", "ispublished": "unpub", "full_text_status": "public", "note": "This paper is declared a work of the U.S. Government and therefore is in the public domain. \n\nThis work was supported by the Office of Naval Research under Contract N00014-76-C-0260. Help and support by Professor Paul Dimotakis and Drs.\nManooch Koochesfahani, Dan Nosenchuck and Dan Lang on this project is acknowledged.\n\nPublished - 388457.pdf
", "abstract": "The effects of a periodic disturbance, applied to the one of the the free streams, on large-scale structure and mixing processes in chemically reacting\nshear layers and wakes were investigated over a range of Reynolds numbers above and below the mixing transition range. Two different methods were employed to measure the amount of chemical product and thus the extent of molecular-scale mixing. Absorption by reacted phenolphthalein provided cross-stream average product thickness and laser induced fluorescence intensity provided the product concentration distribution. These methods provided, in addition, effective flow visualization of the large-scale structures and of their response to the periodic forcing. The detailed effects of periodic forcing on distribution of mixing along a free shear layer are complex, but the predominant, overall effect is to increase mixing at low Reynolds number (in respect to the mixing transition) and to decrease it at high Reynolds number.", "date": "1985-03", "date_type": "published", "id_number": "CaltechAUTHORS:20141210-133626177", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141210-133626177", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "N00014-76-C-0260" } ] }, "other_numbering_system": { "items": [ { "id": "85-0570", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1985-570", "primary_object": { "basename": "388457.pdf", "url": "https://authors.library.caltech.edu/records/9327t-n5e83/files/388457.pdf" }, "pub_year": "1985", "author_list": "Roberts, F. A. and Roshko, A." }, { "id": "https://authors.library.caltech.edu/records/gyy7e-vb990", "eprint_id": 53086, "eprint_status": "archive", "datestamp": "2023-08-19 12:57:44", "lastmod": "2023-10-19 14:31:32", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Rosen-R", "name": { "family": "Rosen", "given": "R." } }, { "id": "Roshko-A", "name": { "family": "Roshko", "given": "A." } }, { "id": "Pavish-D-L", "name": { "family": "Pavish", "given": "D. L." } } ] }, "title": "A two-layer calculation for the initial interaction region of an unseparated supersonic turbulent boundary layer with a ramp", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1980 AIAA.\n\nPublished - 388456.pdf
", "abstract": "The interaction of an unseparated supersonic turbulent boundary layer with a compression corner produces an extremely rapid rise in pressure at the corner, followed by a more gradual increase to the final pressure. In this paper, the flow in the corner region is analyzed by an integral method with the objective of predicting the initial pressure rise. Comparisons with experimental pressure rise data are presented for cases covering supersonic and hypersonic flows of practical interest. Also presented are some calculations and comparisons of downstream pressure distributions obtained by using the predicted corner rise as the first point in an existing inviscid method.", "date": "1980-01", "date_type": "published", "id_number": "CaltechAUTHORS:20141222-110906638", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141222-110906638", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "80-0135", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1980-135", "primary_object": { "basename": "388456.pdf", "url": "https://authors.library.caltech.edu/records/gyy7e-vb990/files/388456.pdf" }, "pub_year": "1980", "author_list": "Rosen, R.; Roshko, A.; et el." }, { "id": "https://authors.library.caltech.edu/records/ejdq8-em991", "eprint_id": 53085, "eprint_status": "archive", "datestamp": "2023-08-19 09:52:30", "lastmod": "2023-10-19 14:31:30", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roshko-A", "name": { "family": "Roshko", "given": "Anatol" } } ] }, "title": "Structure of turbulent shear flows - A new look", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1976 AIAA. \n\nI am indebted for valuable discussions and use of material to many colleagues and students, especially G. L. Brown, J. Konrad and L. Bernal. Names of others are indicated by an asterisk in the list of references. Much of the material in this lecture is based on research supported by the Office of Naval Research under its Fluid Dynamics Program and Project SQUID.\n\nPublished - 388455.pdf
", "abstract": "For many years experimental research in turbulence was devoted to the measurement of various correlations and special functions which had evolved from the statistical theories and from engineering computing methods based on the hierarchy of Reynolds equations. A recent change in direction toward a more deterministic description of turbulent structure has been initiated by the discovery of large coherent structures in several turbulent shear flows. The new point of view suggests that with every shear flow (jet, boundary layer, mixing layer, etc.) is associated an identifiable, characteristic structure; the development of the flow is controlled by the interactions of these structures with each other. An understanding of their properties should give insight into actual physical processes in turbulent flows, such as entrainment, transport, mixing, noise production, gustiness, etc. and should lead to improved methods for analyzing and computing them. Experiments designed to study these properties are aided by recent developments in instrumentation technology such as computer-aided control of the experiments, but the venerable technique of flow visualization is still an indispensable aid.", "date": "1976-01", "date_type": "published", "id_number": "CaltechAUTHORS:20141222-105100548", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141222-105100548", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)" } ] }, "other_numbering_system": { "items": [ { "id": "76-78", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1976-78", "primary_object": { "basename": "388455.pdf", "url": "https://authors.library.caltech.edu/records/ejdq8-em991/files/388455.pdf" }, "pub_year": "1976", "author_list": "Roshko, Anatol" }, { "id": "https://authors.library.caltech.edu/records/pfn6w-msw92", "eprint_id": 53140, "eprint_status": "archive", "datestamp": "2023-08-19 09:14:39", "lastmod": "2023-10-19 14:35:33", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Roshko-A", "name": { "family": "Roshko", "given": "A." } }, { "id": "Thomke-G-J", "name": { "family": "Thomke", "given": "G. J." } } ] }, "title": "Flare-Induced Interaction Lengths in Supersonic, Turbulent Boundary Layers", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1975 AIAA.\n\nPublished - 388454.pdf
", "abstract": "Experimental results are presented for the effects of Mach number, Reynolds number, and corner angle on flare-induced separation of a supersonic, turbulent boundary layer. In particular, measurements were obtained for the variation with flare angle, \u03b1, of the ratio \u2113_0/\u03b4_0 of the upstream interaction length to the boundary-layer thickness at the beginning of the interaction for Mach numbers 2\u2264M\u22644.5, boundary-layer thickness Reynolds numbers 10^5 < R_\u03b4 < 10^6, and adiabatic wall conditions. The model consisted of a hollow cylinder of 12-in. diameter and 51-in. length. Flares of angle 9\u00b0\u2264\u03b1\u226440\u00b0 were attached to the cylinder model at either of two location, viz., at x_c= 14 or 28 in. downstream from the sharp leading edge. Measurements consisted chiefly of surface-pressure distributions. Profiles for the undisturbed (flare-off) boundary-layer were also obtained. By varying the several parameters upstream interaction lengths as large as \u2113_0/\u03b4_0 = 30 were observed. It was found that \u2113_0/\u03b4_0 decreases with increasing Mach number and Reynolds number and, of course, increases with flare angle. It was also found that, for constant \u03b1, when \u2113_0/\u03b4_0 is plotted vs the local skin-friction coefficient, C_(f0), the Mach-number dependence disappears. From this observation, a simple correlation formula was obtained and used to compare results from other investigations, and also to correlate incipient separation data. The present results complement the incipient-separation data obtained previously by us in the next higher decade of Reynolds number and further confirm the trends established there. It was also found that, for large \u03b1, the separated region upstream of the flare has free-interaction characteristics similar to those of upstream-facing steps at high Reynolds number.", "date": "1975-01", "date_type": "published", "id_number": "CaltechAUTHORS:20141223-095148400", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141223-095148400", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "other_numbering_system": { "items": [ { "id": "75-6", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1975-6", "primary_object": { "basename": "388454.pdf", "url": "https://authors.library.caltech.edu/records/pfn6w-msw92/files/388454.pdf" }, "pub_year": "1975", "author_list": "Roshko, A. and Thomke, G. J." }, { "id": "https://authors.library.caltech.edu/records/3ek0g-h0818", "eprint_id": 52556, "eprint_status": "archive", "datestamp": "2023-08-19 06:19:25", "lastmod": "2023-10-18 20:58:40", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Collins-D-J", "name": { "family": "Collins", "given": "Donald J." } }, { "id": "Lees-L", "name": { "family": "Lees", "given": "Lester" } }, { "id": "Roshko-A", "name": { "family": "Roshko", "given": "Anatol" } } ] }, "title": "An experimental study of the near wake of a two-dimensional hypersonic blunt body with mass addition", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 1969 AIAA. \n\nWork supported by A. R. O. and A. R. P. A. under Contract DA-31-124-ARO(D)-33.\n\nPublished - 388453.pdf
", "abstract": "An experimental investigation of the steady, laminar near-wake flow field of a two-dimensional, adiabatic, circular cylinder with surface mass transfer has been made at a free-stream Mach number of 6.0. The pressure and mass-concentration fields associated with the transfer of argon, nitrogen or helium into the near wake were studied for mass transfer from the forward stagnation region, and from the base. For sufficiently low mass transfer rates from the base, for which a recirculating zone exists, the entire near-wake flow field correlates with the momentum flux, not the mass flux, of the injectant, and the mass-concentration field is determined by counter-current diffusion into the reversed flow. For mass addition from the forward stagnation region, the pressure field is undisturbed and the mass-concentration field is nearly uniform in the region of reversed flow. The axial decay of argon mass concentration in the intermediate wake, downstream of the neck, is explained with the aid of an integral solution in the incompressible plane, from which the location of the virtual origin for the asymptotic far-wake solution has been derived as one result.", "date": "1969-01", "date_type": "published", "id_number": "CaltechAUTHORS:20141210-132533513", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141210-132533513", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "DA-31-124-ARO(D)-33" }, { "agency": "Advanced Research Projects Agency (ARPA)" } ] }, "other_numbering_system": { "items": [ { "id": "69-67", "name": "AIAA Paper" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.2514/6.1969-67", "primary_object": { "basename": "388453.pdf", "url": "https://authors.library.caltech.edu/records/3ek0g-h0818/files/388453.pdf" }, "pub_year": "1969", "author_list": "Collins, Donald J.; Lees, Lester; et el." } ]