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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 15:47:48 +0000Studies of Radiant Heat Transfer from Pure Gases
https://resolver.caltech.edu/CaltechETD:etd-01272009-135633
Authors: {'items': [{'id': 'Benitez-Louis-Eugenio', 'name': {'family': 'Benitez', 'given': 'Louis Eugenio'}, 'show_email': 'NO'}]}
Year: 1949
DOI: 10.7907/EG68-PD69
This report contains an outline of some of the experimental measurements and theoretical considerations which are required for the calculation of the emissivity of nitric oxide. Because of lack of suitable apparatus, the experimental part of the program was restricted to the determination of apparent absorption coefficients for the fundamental vibration-rotation band of nitric oxide. Theoretical calculations of emissivity were originally suggested by Dr. Martin Summerfield. The present calculations were made by the use of an approximate procedure which has been developed recently at the Jet Propulsion Laboratory by S. S. Penner for the determination of the emissivity of pure diatomic gases. The results presented in this report facilitate making approximate estimates of the emissivity of nitric oxide as a function of temperature and optical density. For these emissivity calculations it is recommended to correct the experimentally determined apparent absorption coefficients by analogy with available data for carbon monoxide.https://thesis.library.caltech.edu/id/eprint/382I. Experimental Determination of Selected Accommodation Coefficients. II. Experimental Determination of the Heat of Iodine
https://resolver.caltech.edu/CaltechETD:etd-03172009-085837
Authors: {'items': [{'id': 'Angelo-Raymond-Louis', 'name': {'family': 'Angelo', 'given': 'Raymond Louis'}, 'show_email': 'NO'}]}
Year: 1951
DOI: 10.7907/1DD6-8B60
In PART I the results of a study of the accommodation coefficient and its dependence on the temperature of the metal surface are described. The following systems were investigated: oxygen on platinum, carbon dioxide on platinum, nitrogen on platinum, carbon dioxide on tungsten, and carbon dioxide on nickel. All systems exhibit similar characteristics; i.e., a rapid rise to a maximum value of the accommodation coefficient in the region of low filament temperatures followed by a gradual decrease to a constant value as the filament temperature is increased, bulb temperature remaining constant.
Maximum Constant value
Oxygen-platinum .98 .68
Nitrogen-platinum .97 .50
CO2 -platinum .56 .35
CO2 -tungsten .93 .80
CO2 - nickel .68 .47
This general behavior of the accommodation coefficient substantiates findings reported earlier by Oliver (13) for other gas-metal systems.
The experimentally determined values of the accommodation coefficient are applied to a theoretical relation obtained by application of the theory of absolute reaction rates (10). The theoretical expression is shown to be in semiquantitative agreement with the experimental data.
In PART II the "hot wire" method is used to determine the heat of dissociation of iodine. The experimentally determined value is 36.9 kcal/mole at 600°K. The presently accepted value for this temperature is 35.17 kcal/mole. Provided a wire can be found which is not corroded by fluorine, the present results suggest a useful method for determining the heat of dissociation of fluorine.https://thesis.library.caltech.edu/id/eprint/987Emissivity Calculations for Carbon Monoxide
https://resolver.caltech.edu/CaltechETD:etd-03302009-062500
Authors: {'items': [{'id': 'Ostrander-Max-Howell', 'name': {'family': 'Ostrander', 'given': 'Max Howell'}, 'show_email': 'NO'}]}
Year: 1951
DOI: 10.7907/7DDZ-WA46
The purpose of this report is to utilize a sound theoretical formulation combined with the best available experimental data on integrated absorption and rotational line-width, for the calculation of emissivities of carbon monoxide at room temperatures under conditions where overlapping between rotational lines is negligibly small.
The results of the present investigation indicate that calculated emissivities of carbon monoxide at room temperature are in excellent agreement with empirically observed data published by Hottel and Ullrich. The theoretical dependence of emissivity upon optical density at low optical density and at room temperature has been shown to follow the experimental observations almost exactly. For low optical densities the calculated emissivity is found to be nearly proportional to the assumed rotational line-width, thus emphasizing the need for accurate line-width determinations at all temperatures. The calculated dependence of emissivity on rotational line-width permits the determination of emissivity not only as a function of temperature, total pressure, and optical density, but also as a function of concentration of optically inert gas. For numerical calculations of this type it is necessary to obtain experimental data for the dependence of rotational line-width on the concentration of non- emitting gases.
The present calculations supplement earlier theoretical emissivity calculations, which are valid only at elevated total pressures where extensive overlapping of rotational lines occurs. The range of pressures in which overlapping between rotational lines is neither extensive nor negligibly small has been considered only very briefly and requires further examination.https://thesis.library.caltech.edu/id/eprint/1207The Evaporation Rate of Liquid Droplets in a Hot Gas
https://resolver.caltech.edu/CaltechETD:etd-09082004-114120
Authors: {'items': [{'id': 'Hartwig-Frederic-William', 'name': {'family': 'Hartwig', 'given': 'Frederic William'}, 'show_email': 'NO'}]}
Year: 1952
DOI: 10.7907/NY38-9J57
Calculations have been carried out in order to determine the rate of evaporation of a liquid droplet surrounded by hot gases. The present study represents an extension of earlier work by Penner on evaporation rates for isothermal droplets. Thus, allowance was made for temperature gradients withing the droplet (a) by considering a droplet composed of an isothermal core and an isothermal shell and (b) by utilizing the actual termperature profile in the droplet as established as the result of a heat balance between thermal conduction within the droplet, convective heat transfer to the droplet, and cooling produced by evaporation at the droplet surface.
The results obtained for the shell model of the evaporating droplet were found to be in satisfactory agreement with the known data for evaporations of isothermal droplets, independently of the thickness chosen for the isothermal shells. On the other hand, the laborious conduction solution led to somewhat different results. The origin of the detailed deviations is not clear at this time and requires additional study.https://thesis.library.caltech.edu/id/eprint/3376Effect of Vibrational Excitation on the Theoretical Performance of the Stoichiometric Carbon-Oxygen Propellant System
https://resolver.caltech.edu/CaltechETD:etd-03302009-082354
Authors: {'items': [{'id': 'Schroeder-Joseph-Herman', 'name': {'family': 'Schroeder', 'given': 'Joseph Herman'}, 'show_email': 'NO'}]}
Year: 1952
DOI: 10.7907/BGFA-6E97
Accurate calculations to evaluate the performance of the stoichiometric carbon-oxygen propellant system have been carried out for nozzle flow with and without chemical reactions and with and without vibrational adjustment. The calculations show that, for frozen chemical flow, a lag of vibrational energy states at chamber conditions nearly doubles the reduction in Isp, as compared with flow in which complete vibrational equilibrium is maintained. On the other hand, lags in vibrational adjustment have practically no effect on the theoretical performance of hot propellant systems if chemical equilibrium is maintained during nozzle flow. The preceding conclusions are in agreement with the results on other propellant systems obtained previously by use of an approximate evaluation procedure.https://thesis.library.caltech.edu/id/eprint/1211I. Integrated Intensity Measurements for Vibration-Rotation Bands of Carbon Dioxide. II. Total Absorptivity Measurements on Carbon Dioxide at Room Temperature
https://resolver.caltech.edu/CaltechETD:etd-03232009-081744
Authors: {'items': [{'id': 'Holm-Robert-Joseph', 'name': {'family': 'Holm', 'given': 'Robert Joseph'}, 'show_email': 'NO'}]}
Year: 1952
DOI: 10.7907/RN61-AX46
I. This study contains an outline of the experimental measurements performed in order to determine integrated intensities of various vibration-rotation bands of carbon dioxide by use of standard techniques with a Perkin-Elmer spectrometer.
II. Total absorptivity measurements on carbon dioxide at room temperatures were made in a pressurized gas cell provided with transparent windows.https://thesis.library.caltech.edu/id/eprint/1075Thermodynamic Functions of Polyelectronic Atoms at Very High Temperatures
https://resolver.caltech.edu/CaltechETD:etd-04252003-104736
Authors: {'items': [{'id': 'Meghreblian-Robert-Vartan', 'name': {'family': 'Meghreblian', 'given': 'Robert Vartan'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/88PE-S208
<p>A convergent series representation for the internal partition function of polyelectronic atoms is obtained by assuming a covolume equation of state for the gas as previously applied by Fermi and Urey to the hydrogen atom.</p>
<p>The present investigation is limited to those cases wherein only extranuclear electronic excitation occurs. The contribution of these electronic states to the thermodynamic functions is obtained from an acceptable approximation to the sum of the convergent series for the partition function.</p>
<p>It is shown that at relatively low temperatures (3000 degrees K), the customary method of evaluating the internal partition function (based on the assumption of an ideal gas) agrees to within a few percent with the results obtained from the covolume treatment. However, at higher temperatures the increase in size of the excited atoms, along with the appearance of charged particles produced by ionization, render the ideal gas treatment inadequate. Since the interaction potentials of charged particles are not known in general, an approximate procedure, which neglects these interactions, is suggested for analyzing a system wherein ions and free electrons constitute a small fraction of the total population. This procedure should be useful for treating gaseous mixtures to temperatures of about 10,000 degrees K.</p>https://thesis.library.caltech.edu/id/eprint/1496Some Experimental Studies of Laminar Burning Velocity
https://resolver.caltech.edu/CaltechETD:etd-04232003-091500
Authors: {'items': [{'id': 'Poorman-Herbert-R', 'name': {'family': 'Poorman', 'given': 'Herbert R.'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/J2N7-T584
One of the important physical parameters in flame propagation is the laminar burning velocity. A great many experimental measurements of the burning velocity have been made using a variety of experimental techniques. Furthermore, the problem has been studied theoretically by a number of different investigators. Extensive references to the original literature may be found in the books by Lewis and von Elbe(1) and by Jost(2).
This thesis is concerned with experimental studies of flame propagation in acetylene-oxygen systems containing the inert gases argon, carbon dioxide, helium, and nitrogen. These studies are introduced with a survey of experimental techniques for measuring the laminar burning velocity in premixed gases. Next, some new experimental measurements obtained by use of a small burner tube at atmospheric pressure are described. The new data are interpreted qualitatively by utilizing a thermal theory of laminar flame propagation.https://thesis.library.caltech.edu/id/eprint/1463Spectroscopic Studies of OH in Flames. I. Theoretical Investigations of Distortions Produced by Temperature Gradients, Self-Absorption and Changes in Spectral Line-Shape. II. Experimental Studies on Acetylene-Oxygen Flames Burning at Atmospheric Pressure
https://resolver.caltech.edu/CaltechETD:etd-04232003-083315
Authors: {'items': [{'id': 'Elliott-Benton-Holford', 'name': {'family': 'Elliott', 'given': 'Benton Holford'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/Y37J-RF90
A theoretical investigation has been made to determine quantitatively the effects of temperature gradients, self-absorption, and spectral line-shape on the apparent rotational temperatures of OH.
Emission experiments have been performed on the inner cone and on the outer cone of an oxygen-acetylene flame to determine the rotational temperature of the upper energy state of OH.https://thesis.library.caltech.edu/id/eprint/1461Some Considerations in the Application of a Gas Turbine Cycle to the Manufacture of Nitric Oxide
https://resolver.caltech.edu/CaltechETD:etd-05022003-112115
Authors: {'items': [{'id': 'MacLeod-Gordon-John', 'name': {'family': 'MacLeod', 'given': 'Gordon John'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/YN04-XS79
Certain problems associated with the application of a gas turbine cycle to the manufacture of nitric oxide are investigated. The feasibility of quenching the nitric oxide decomposition reaction with a De Laval nozzle is demonstrated. Thermochemical studies show that yields of nitric oxide approaching one percent are attainable in a gas turbine cycle. The severe turbine blade cooling problem can be surmounted with the use of either transpiration cooling or film cooling. Transpiration cooling with internal liquid vaporization is found to be the most promising method. The coolant requirements amount only to approximately one percent of the main stream mass flow per cooled-turbine-blade row. The effect of transpiration and film cooling upon cycle performance is negligible. Although all the problems associated with the application of a gas turbine cycle to the manufacture of nitric oxide appear to be surmountable, no attempt is, however, made in this study to ascertain the economical feasibility of the process. The answer to this question involves factors which are not purely technical and thus lies outside the scope of the thesis.https://thesis.library.caltech.edu/id/eprint/1571Activation Energies of Global Reactions in Laminar Flame Propagation
https://resolver.caltech.edu/CaltechETD:etd-05092003-084313
Authors: {'items': [{'id': 'Ritter-Darrell-Lloyd', 'name': {'family': 'Ritter', 'given': 'Darrell Lloyd'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/8539-Z537
A survey of experimentally determined values for the laminar burning velocity of premixed, laminar hydrocarbon-air and hydrogen-oxygen-nitrogen flames shows considerable scatter between results obtained by different investigators. Within the limits of experimental reproducibility of burning velocities, it is possible to correlate measured burning velocities on the assumption that a single rate-controlling or global reaction exists. Correlation of experimental data by use of a global reaction has been made on the basis of two simplified relations for the laminar burning velocity.
The first relation was obtained by the use of an intuitive argument based on the idea that the laminar burning velocity is proportional to the square root of a second order reaction rate, with the rate-controlling reaction step depending on the first power of the initial fuel and oxygen concentrations. For lean mixtures the global activation energy was found to have a value of about 22 Kcals/mole, and for rich mixtures it has a value of roughly 56 Kcals/mole.
The second expression for the calculation of laminar burning velocity is based on a theoretical equation derived by Semenov for a thermal mechanism controlling flame propagation in rich hydrocarbon-air mixtures. Application of this relation leads to the conclusion that a global reaction with an activation energy of 87 Kcals/mole correlates rich hydrocarbon-air burning velocities, well within the limits of reproducibility of experimental data.
A study of the effect of the concentration of N[subscript 2] in the oxidizing mixture shows an apparent dependence of the global activation energy on the amount of diluent gas. This observation suggests that although good correlation of experimental data has been obtained, by using the concept of a global activation energy, the results are not of fundamental significance but should be regarded simply as useful empirical methods for correlating experimental data. It is possible that additional theoretical work will lead to a modified expression for the laminar burning velocity, which not only permits correlation of experimental data, but also yields a global activation energy which is independent of the concentration of inert diluents.https://thesis.library.caltech.edu/id/eprint/1689Properties of Ethylene Oxide and Hydrazine Related to their Use as Propellants
https://resolver.caltech.edu/CaltechETD:etd-05092003-093602
Authors: {'items': [{'id': 'Robison-William-Clay', 'name': {'family': 'Robison', 'given': 'William Clay'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/QHQT-NG37
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
PART I. Ethylene Oxide as a Monopropellant.
Thermodynamic calculations to determine the theoretical performance of ethylene oxide as a monopropellant have been carried out for various possible decomposition reactions. A survey of the literature on the kinetics of the thermal decomposition of ethylene oxide is presented.
PART II. Experimental Measurement of the Heats of Dissociation of Hydrazine - Water and Hydrazine - Alcohol Systems.
A glass apparatus has been constructed for determining heats of dissociation at low temperatures. Published data on hydrazine-water mixtures have been checked. The heat of dissociation of N[subscript2] H[subscript 4][...]CH[subscript 3]OH has been found to be 8.62 Kcals/mole.https://thesis.library.caltech.edu/id/eprint/1691Tables of Bond and Resonance Energies for Estimating Standard Heats of Fformation
https://resolver.caltech.edu/CaltechETD:etd-04282003-103959
Authors: {'items': [{'id': 'Offtermatt-Wilbur-Francis', 'name': {'family': 'Offtermatt', 'given': 'Wilbur Francis'}, 'show_email': 'NO'}]}
Year: 1953
DOI: 10.7907/TZFF-RW53
Tables of bond and resonance energies have been redetermined by using the most recent thermochemical data available. The use of the data is illustrated for the calculations of standard heats of formation of chemical compounds, including propellants.https://thesis.library.caltech.edu/id/eprint/1526Burning of Single Droplets of Hydrocarbon Fuels in Oxidizing Atmospheres
https://resolver.caltech.edu/CaltechETD:etd-12052003-093547
Authors: {'items': [{'id': 'Perkins-Carlton-Kay', 'name': {'family': 'Perkins', 'given': 'Carlton Kay'}, 'show_email': 'NO'}]}
Year: 1954
DOI: 10.7907/DMX1-0Y63
Experiments have been conducted in order to determine the burning, rates of single droplets of liquid fuels in oxidizing atmospheres. N-heptane and absolute ethyl alcohol were tested in nitrogen-oxygen mixtures for oxygen weight fractions between 0.10 and 0.90. Measurements were made also for benzene and toluene; for oxygen weight fractions greater than for air, a carbon residue formed during the burning of these fuels, which made it impossible to obtain accurate data. For all nitrogen-oxygen mixtures it was found that the mass burning rate of single droplets of fuel is proportional to the first power of the drop diameter.
The theoretical analysis on the burning of single droplets of fuels in an oxidizing atmosphere by Goldsmith and Penner was used to obtain values for the evaporation constants of the fuels tested. The experimentally determined values of the evaporation constants were found to be in good agreement with the calculated values for all fuels tested which did not form carbon.https://thesis.library.caltech.edu/id/eprint/4787The Thermal Theory of Laminar Flame Propagation for Hydrogen-Bromine Mixtures
https://resolver.caltech.edu/CaltechETD:etd-01152004-120851
Authors: {'items': [{'id': 'Mileson-Donald-Francis', 'name': {'family': 'Mileson', 'given': 'Donald Francis'}, 'show_email': 'NO'}]}
Year: 1954
DOI: 10.7907/WN9C-Q975
The thermal theory of laminar flame propagation for hydrogen-bromine mixtures is described. The method of analysis follows the earlier work of von Karmen and Millan and of von Karmen and Penner. The problem is materially simplified by introducing the steady-state approximation of classical chemical kinetics for the concentrations of H- and Br-atoms.
The general formulation of the problem is presented in Section II.
Approximate solutions of the relevant mathematical problems, utilizing various procedures developed by von Karman and his collaborators, are given in Sections III to V for bromine-rich, stoichiometric, and hydrogen-rich mixtures, respectively.
Numerical values for the physio-chemical parameters, which are required for the calculation of absolute values for the burning velocities, are considered in Section VI.
The calculated burning velocities are compared in Section VII with experimental results obtained by R. C. Anderson and his collaborators. Reference to Section VII shows that the variation of the observed burning velocities with mixture ratio is predicted correctly by the theoretical calculations. Absolute values for the laminar burning velocity cannot be estimated with certainty because of the possible existence of large errors resulting from extrapolation of low-temperature kinetics and heat conductivity data.https://thesis.library.caltech.edu/id/eprint/188Vibrational Relaxation Times of Gaseous Mixtures of Diatomic Molecules and their Effect on Rocket Performance
https://resolver.caltech.edu/CaltechETD:etd-01122004-094512
Authors: {'items': [{'id': 'Penny-Harmon-Charles', 'name': {'family': 'Penny', 'given': 'Harmon Charles'}, 'show_email': 'NO'}]}
Year: 1954
DOI: 10.7907/Y2D2-M834
The present methods available for the determination of the magnitudes of the vibrational relaxation times of molecules are discussed and the recently developed theory of Schwartz, Slawsky, and Herzfeld is used to compute the variation with temperature of the collisional vibrational excitation probabilities of mixtures of N2 and 02, and of H2 and HF. The results are used to estimate the extent of vibrational temperature lag in the hydrogen-fluorine rocket motor.https://thesis.library.caltech.edu/id/eprint/129Correlation of Laminar Flame Velocities for Hydrocarbon-Oxygen-Inert Gas Mixtures
https://resolver.caltech.edu/CaltechETD:etd-12042003-105228
Authors: {'items': [{'id': 'Crowe-Thomas-Huston', 'name': {'family': 'Crowe', 'given': 'Thomas Huston'}, 'show_email': 'NO'}]}
Year: 1955
DOI: 10.7907/29MY-5D14
A thermal theory of laminar flame propagation for hydrocarbon-oxygen flames is described. The method of analysis follows the earlier work of von Karman and his collaborators. The problem is greatly simplified by the introduction of several approximations and assumptions.
In Section III the problem is formulated and approximate solutions are given for hydrocarbon-oxygen flames, assuming a second order rate-controlling step. Approximate analytic solutions have been obtained for all mixture ratios.
Hydrocarbon-oxygen-inert gas mixtures are considered in Section IV. A second order rate-controlling step is again assumed and solutions are given for various initial gas compositions.
An attempt is made to correlate experimentally determined burning velocity data in Section V. Reference to Section V shows that a good correlation was obtained only for lean mixtures. Absolute values for the laminar burning velocity cannot be estimated because of the lack of data concerning reaction mechanism and specific reaction rate constants.https://thesis.library.caltech.edu/id/eprint/4765The Burning of Single Drops of Fuel in Oxidizing Atmospheres
https://resolver.caltech.edu/CaltechETD:etd-12182003-091848
Authors: {'items': [{'email': 'captmarty@verizon.net', 'id': 'Goldsmith-Martin', 'name': {'family': 'Goldsmith', 'given': 'Martin'}, 'show_email': 'NO'}]}
Year: 1955
DOI: 10.7907/E4YT-5B12
<p>The burning of single, isolated drops of fuel in a quiescent oxidizing atmosphere has been investigated theoretically and experimentally. Two theories are presented. The first, called the diffusion theory, rests on the assumption that the rate of burning is determined by the rate at which the reactants are delivered by diffusion to the flame front surrounding the liquid drop. The second, or thermal theory is based on the assumption that chemical reaction rates govern the rate of burning of the droplet.</p>
<p>The effects on droplet burning rate of changes in the composition, temperature, and pressure of the surrounding oxidizing atmosphere have been investigated experimentally. A preliminary study has also been made of the effect of forced convection on droplet burning.</p>
<p>It is found that the thermal theory of droplet burning does not adequately explain the observed variations in droplet burning rate as the composition and temperature of the surrounding atmosphere are varied. On the other hand, substantial agreement is found between the results of the diffusion theory and experimental data.</p>https://thesis.library.caltech.edu/id/eprint/5037Interference Effects During Burning in Air for Two Stationary N-Heptane Droplets
https://resolver.caltech.edu/CaltechETD:etd-01202004-145717
Authors: {'items': [{'id': 'Rex-James-Foster', 'name': {'family': 'Rex', 'given': 'James Foster'}, 'show_email': 'NO'}]}
Year: 1955
DOI: 10.7907/334Z-RA03
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstraact is included in .pdf document.
In order to gain some understanding of droplet interference during burning, experiments have been conducted for the determination of the evaporation constant and flame shapes of two closely spaced n-heptane droplets burning in air. Droplets of approximately the same and of different diameters were used at various distances between the droplet centers.
Experimental results on flame shapes and evaporation constants for closely spaced droplets show somewhat surprising behavior. Thus the apparent flame shape changes very little during the burning of the droplet. The square of the droplet diameter decreases linearly with time for fixed spacing between droplet centers, at least within the experimental limits of accuracy. Since geometrically different conditions are produced continuously during burning, the observed independence of the slope of plots for the square of droplet diameter vs time is not obviously expected. Furthermore, for droplets of different average initial diameters [...], the frequency, [...], where [...] is the usual evaporation constant, is well represented as a universal function of the initial spacing between droplet centers ([...]) or adjacent droplet surfaces ([...]).
The evaporation constant [...] for constant [...], and the frequency [...] for arbitrary values of [...], increase at first as [...] is reduced and then decrease again. For large values of [...], [...] approaches the numerical value measured in studies on the burning of single droplets. This behavior can be understood in terms of a competition between heat losses to the outside from the flame front surrounding a single droplet, which decrease as the droplets are brought together, and oxygen-deficient atmospheres, which are more likely to occur for very small values of [...].
Although an acceptable empirical correlation of experimental measurements has been obtained, the processes which determine interference during droplet burning are as yet not understood. In view of the possible practical importance of interference during burning in sprays, additional laboratory studies on the burning of simple geometric arrays, other than two droplets, appear to be indicated.https://thesis.library.caltech.edu/id/eprint/248The Emissivity of Hydrogen Atoms at High Ttemperatures
https://resolver.caltech.edu/CaltechETD:etd-11212003-145619
Authors: {'items': [{'id': 'Benton-William-Curtis', 'name': {'family': 'Benton', 'given': 'William Curtis'}, 'show_email': 'NO'}]}
Year: 1955
DOI: 10.7907/G0S8-8Q90
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
A method is described for making estimates of the total emissivity of hydrogen in the temperature and pressure ranges where hydrogen atoms predominate under equilibrium conditions. For a characteristic geometrical depth of 50 cm, and temperatures of the order of 12,500[degrees]K and higher, with pressures of the order of 100 atmos and higher, the emissivity approaches unity [...] while for temperatures of the order of 9500[degrees]K and lower, with pressures of the order of 10 atmos and lower, the emissivity approaches zero [...]. The variations of the emissivity between these approximate limits are shown graphically as functions of temperature and pressure with the geometrical depth set at 50 cm. The variation of the emissivity with geometrical depth is also shown graphically at 12,600[degrees]K and 20 atmos.https://thesis.library.caltech.edu/id/eprint/4622On the Burning of Single Drops of Monopropellants
https://resolver.caltech.edu/CaltechETD:etd-12032003-112346
Authors: {'items': [{'id': 'Kiley-Donald-Walter', 'name': {'family': 'Kiley', 'given': 'Donald Walter'}, 'show_email': 'NO'}]}
Year: 1955
DOI: 10.7907/33WQ-4M23
A simplified theoretical treatment has been developed for the burning of single drops of monopropellants. Evaporation constants and the ratios of flame to droplet radii have been calculated for the following monopropellants burning in an inert atmosphere: hydrogen peroxide, nitromethane, hydrazine, ethylene oxide, ozone and nitrous oxide. Compared with the results of similar calculations for fuels burning in air, much smaller flame radii were obtained, while the evaporation constants were found to fall in the same range as before.
Attempts at burning single droplets of monopropellants (e.g. hydrazine and nitromethane) in a nitrogen atmosphere were unsuccessful. Monopropellant droplets burning stably in air were found to extinguish if the oxygen was removed during burning. These experimental findings probably reflect the well-known difficulties encountered in monopropellant operation, which is usually successful only if a suitable reaction catalyst is available. The applicability of calculated monopropellant burning rates to practical cases cannot be assessed at this time.
Single droplets of hydrazine and nitromethane were burnt in air and evaporation constants determined experimentally. The measured rate for nitromethane was found to be in good agreement with calculated results for heterogeneous burning of fuel droplets in air. The measured rate for hydrazine was found to be considerably higher than the value calculated for fuel droplets burning in air or for monopropellant droplets burning in an inert atmosphere. This latter result probably indicates that the assumption of a diffusion flame for the burning of hydrazine in air is not valid, i.e., the hydrazine decomposes throughout the region between the liquid surface and the "flame surface" rather than reacting instantaneously at the "flame surface".https://thesis.library.caltech.edu/id/eprint/4739Carbon Formation from Acetylene in the Shock Tube
https://resolver.caltech.edu/CaltechETD:etd-03182004-142409
Authors: {'items': [{'id': 'Bennett-Eugene-Newell', 'name': {'family': 'Bennett', 'given': 'Eugene Newell'}, 'show_email': 'NO'}]}
Year: 1956
DOI: 10.7907/GB80-GE14
The use of the shock tube for the study of carbon formation from acetylene has been considered theoretically and studied experimentally.
In the calculations, the state of the gas is determined behind incident and reflected shocks for a wide range of shock strengths and for various excitation models of the internal degrees of freedom. A simple mechanism has been assumed for the thermal decomposition, namely the formation of solid carbon and hydrogen. Estimates are presented for the minimum times spent by the gas in a uniform state at the elevated temperatures behind reflected shocks.
The shock strengths required to initiate decomposition of acetylene at various pressures have been investigated experimentally. Temperature estimates and shock velocity measurements suggest that the effective specific heat ratio approaches the equilibrium value. Spectroscopic studies have been carried out to determine the light emitted in a narrow wave length region during chemical decomposition behind reflected shocks. The results show that the intensity distribution follows the black-body emission law. Therefore, a two-color method may be used in future studies for determining the temperature as a function of time behind carbon forming shocks.https://thesis.library.caltech.edu/id/eprint/992I. Interference During Burning of Body-Centered Cubic Arrays of Nine Fuel Droplets in Air. II. Spray Formation and Evaporation
https://resolver.caltech.edu/CaltechETD:etd-03252004-094228
Authors: {'items': [{'id': 'Kanevsky-Joseph-Norman', 'name': {'family': 'Kanevsky', 'given': 'Joseph Norman'}, 'show_email': 'NO'}]}
Year: 1956
DOI: 10.7907/JHWV-HB29
In order to gain some understanding of interference effects during the combustion and evaporation of fuel sprays, simple three-dimensional body-centered cubic arrays of nine n-heptane or nine methyl alcohol droplets burning in air have been studied. Different cube sizes were used to vary the amount of interference obtained during combustion of the droplets. Photographic studies of the center droplet in this nine-droplet array were made in order to determine the qualitative effects of droplet spacing on the evaporation constant (K') while combustion was in progress and to determine whether the mass rate of burning was proportional to the first power of droplet diameter for a three-dimensional array of droplets.
Experimental results indicate that, when the droplets are in close proximity and the flames completely merged, the evaporation constant is reduced by 40 percent below the value obtained for minimum interference. A 25 percent increase in the evaporation constant over single-droplet values for K' was noted when the droplet spacing was altered to reduce local heat losses from the flame fronts. The results obtained from studies of the center droplet substantiate Probert's assumption (Ref. 38) that the square of droplet diameter decreases linearly with time.
Unsuccessful attempts to study the combustion of liquid bipropellant mixtures and to examine the "burning" of red fuming nitric acid in an ammonia atmosphere are described.
In Part II, a general discussion of information available on the disintegration of liquid jets, spray characteristics, mean droplet size, droplet-size distribution, and spray evaporation is presented. The use of similarity considerations in analyzing spray-nozzle performance is demonstrated. Calculation of K' for a spray from experimental spray evaporation data is described and the results of these calculations tabulated.https://thesis.library.caltech.edu/id/eprint/1108Physico-Chemical Processes Behind Shock Fronts
https://resolver.caltech.edu/CaltechETD:etd-07132004-150103
Authors: {'items': [{'id': 'Harshbarger-Frederick-Clay', 'name': {'family': 'Harshbarger', 'given': 'Frederick Clay'}, 'show_email': 'NO'}]}
Year: 1957
DOI: 10.7907/YYJF-HM80
Part I: Introduction to the Study of Physico-Chemical Phenomena by the Use of Shock Tubes.
The use of the shock tube for the determination of physico-chemical parameters at elevated temperatures is surveyed. We first describe the principles and performance of various shock-tube designs. Next the use of a number of measuring techniques suitable for shock-tube studies is discussed. This section is followed by a summary of representative determinations of physico-chemical parameters behind incident and reflected shock waves.
Part II: Experimental Studies of Reactions Behind Shocks.
The original experimental research involved the study of two chemical reactions. First we describe an unsuccessful attempt to produce hydrazine from ammonia. Second, carbon formation from acetylene is considered theoretically and experimentally. In the calculations, the state of the gas is determined behind the incident and reflected shocks, preceding chemical reaction. Estimates are made for the minimum times spent by the gas in a uniform state at the elevated temperatures behind reflected shocks. The experimental studies led to a new method for making simultaneous light emission and absorption measurements. A kinetic interpretation is given to the induction time necessary to form carbon after the passage of the reflected shock. Spectroscopic studies are presented which indicate that the emitted radiation associated with carbon formation follows a blackbody distribution law. A two-color method has been developed for the determination of temperature as a function of time behind carbon-forming shocks.https://thesis.library.caltech.edu/id/eprint/2872Part I. Experimental and Theoretical Studies on Heterogeneous Diffusion Flames. Part II. Spectroscopic Studies of Flames
https://resolver.caltech.edu/CaltechETD:etd-10262004-152916
Authors: {'items': [{'id': 'Fuhs-Allen-Eugene', 'name': {'family': 'Fuhs', 'given': 'Allen Eugene'}, 'show_email': 'NO'}]}
Year: 1958
DOI: 10.7907/ENEM-BM84
Three topics concerned with heterogeneous diffusion flames are considered in Part I.
Experiments have been conducted to determine the interference effects during burning for droplet arrays. The burning rate law applicable for single droplets has been found to be valid also for two-, five-, and nine-droplet arrays.
A heterogeneous diffusion flame formed between liquid sodium and gaseous titanium tetrachloride was found to deposit small particles of titanium on the combustion chamber wall. The burning rate of liquid sodium, which is related to the rate of production of titanium, was determined experimentally.
The scaling procedures developed by several authors for liquid-fuel rocket engines have been generalized. In these theoretical studies we have used the functional results derived in our investigations of droplet burning. The generalized analysis indicates that an attempt to maintain complete similarity on scaling results in contradictions. For this reason a program on selected scaling procedures is indicated.
In Part II the apparent emission profiles of a turbulent flame are described in terms of a wrinkled laminar flame model. A distribution function, which assigns a probability for the occurrence of the laminar flame at a particular position within the turbulent flame brush, determines the apparent emission profiles. The inverse problem of determining the probability function from observed emission profiles has also been solved.
It is possible to correlate the ratio of the apparent spectral intensities of two rotational lines with the equivalence ratio of a laminar flame. Assuming that this correlation applies also to other flames, we have determined the equivalence ratio in the critical zone of a reverse-jet stabilized flame in a duct. The equivalence ratio as a function of radial distance from the duct axis has also been measured. The results indicate that there appears to be a single equivalence ratio curve at blow-off, regardless of jet composition, provided the blow-off velocity is considered to be a function of critical zone equivalence ratio.https://thesis.library.caltech.edu/id/eprint/4261Emissivities and Absorptivities of Gases
https://resolver.caltech.edu/CaltechETD:etd-01232006-143205
Authors: {'items': [{'id': 'Thomson-James-Alex-Lloyd', 'name': {'family': 'Thomson', 'given': 'James Alex Lloyd'}, 'show_email': 'NO'}]}
Year: 1958
DOI: 10.7907/2HJG-SD13
Equilibrium emissivities and absorptivities of heated gases have been computed from spectroscopic data. Several problems have been studied:
(1) The relation between equilibrium absorptivities and equilibrium emissivities for diatomic and polyatomic molecules has been investigated. Our theoretical results provide a satisfactory correlation of available experimental data for heated water vapor but not for carbon dioxide. The origin of the failure of the theory for carbon dioxide is discussed in detail.
(2) The available, empirically determined, emissivity data for water vapor have been correlated in terms of a statistical model for the distribution of spectral lines within well-defined wavelength regions corresponding to the stronger vibration-rotation bands. This correlation provides a useful framework for the extrapolation of measured emissivity data to temperatures and pressures somewhat different from those used to obtain the experimental data.
(3) The equilibrium emissivity of heated NO has been calculated for the conditions under which this molecule exists in high-temperature air during reentry of hypersonic missiles. An extension of the Mayer-Goody statistical model was used for emissivity calculations on NO. Our semi-analytical results are in acceptable agreement with a simpler numerical analysis of Kivel, Mayer and Bethe.
The original investigations of gas absorptivities and emissivities are introduced with a brief survey of basic theoretical results. An attempt has also been made to calculate the dipole moments and low energy transition probabilities for HF, HCl, and HBr. In this study it was found that the intensities of lines lying in the infrared are very sensitive to the details of the approximating wavefunctions. A considerably more detailed description of the wavefunctions than is available at present is required to make confident predictions of absolute intensities from first principles.https://thesis.library.caltech.edu/id/eprint/292Shock-Induced C₂H₂ Pyrolysis and CO Emissivity
https://resolver.caltech.edu/CaltechETD:etd-10072004-144737
Authors: {'items': [{'id': 'Hooker-William-Joseph', 'name': {'family': 'Hooker', 'given': 'William Joseph'}, 'show_email': 'NO'}]}
Year: 1958
DOI: 10.7907/J37Y-C144
<p>PART I: Shock Tube Studies of Acetylene Decomposition</p>
<p>Extensive experimental studies have been conducted on the rate of decomposition of argon-acetylene mixtures by means of shock waves. Activation energies of 26 and 33 kcal/mole, respectively, have been found for the first- and second-order decomposition reactions of acetylene.</p>
<p>A well defined curve of temperature versus induction time for incipient carbon formation has been established. Analysis of these data suggests that possibly a somewhat better correlation is obtained for decomposition reactions of order n=1 and n=1.5 than for n=2. The corresponding activation energies are 10, 13 and 16 kcal/mole for n= 1, 1.5 and 2, respectively.</p>
<p>The effects of impurity and diluent gas radiation, as well as molecular and solid particle light scattering, have been shown to have a negligibly small influence on the results.</p>
<p>PART II: An Analysis of Equilibrium Infrared Gas Emissivities for Diatomic Molecules Based on a Just-overlapping Rotational Line Model</p>
<p>General equations are developed for the engineering emissivity of diatomic molecules with equally intense R- and P-branches and just-overlapping rotational line structures. Integral expressions for the emissivity are evaluated by exact numerical integration and by approximate series representations.</p>
<p>The results are applied to the molecules CO and HC ℓ. Comparisons are made with emissivity predictions for the same molecules with a completely overlapped rotational line model and an isolated rotational line model. The theoretical emissivity calculations for CO are in fair accord with empirically determined estimates.</p>https://thesis.library.caltech.edu/id/eprint/3973Theoretical Studies in Heterogeneous Combustion
https://resolver.caltech.edu/CaltechETD:etd-01122006-130627
Authors: {'items': [{'id': 'Williams-Forman-Arthur', 'name': {'family': 'Williams', 'given': 'Forman Arthur'}, 'show_email': 'NO'}]}
Year: 1958
DOI: 10.7907/F9A8-VN10
The theory of the steady-state burning of a single spherically-symmetric liquid monopropellant droplet in an infinite inert atmosphere is formulated. Numerical solutions for the temperature and composition profiles and burning rate are obtained in the case of a one-step chemical reaction of the second order. It is shown that the size and location of the reaction zone depend strongly upon the activation energy. Approximate analytical solutions for the burning rate which are valid for large activation energies are obtained for arbitrary chemical reactions. The results indicate that the mass burning rate is proportional to the droplet radius raised to a power which varies from two at small activation energies to unity at large activation energies.
The Shvab-Zeldovich formulation of the problem of burning of initially unmixed systems is developed and applied to the case of a single fuel droplet burning in an infinite oxidizing atmosphere. Some simplification over other methods for treating this problem is obtained, and the burning rate is shown to be unaffected by a distributed reaction zone when the Lewis number is unity.
A general statistical formalism for describing the behavior of sprays is presented, which includes the effects of droplet growth, the formation of new droplets, collisions and aerodynamic forces. The method is applied to the problem of the determination of the size distribution of a spray formed by the impingement of two streams of droplets of known properties. It is shown that if the two incident jets have a size distribution of a generalized Rosin-Rammler type, then the resulting spray belongs to the same class of distributions. The size history of evaporating sprays is also obtained from the theory. A spray combustion analysis given by Probert is extended to include more general size distributions and the effects of droplet interactions and relative motion of the droplets and the fluid. It is shown that sprays of a uniform size yield the highest combustion efficiency.https://thesis.library.caltech.edu/id/eprint/139Spectroscopic Studies of Heated Salts Behind Shock Fronts
https://resolver.caltech.edu/CaltechETD:etd-01272006-131318
Authors: {'items': [{'id': 'Dawson-Victor-Charles-Douglas', 'name': {'family': 'Dawson', 'given': 'Victor Charles Douglas'}, 'show_email': 'NO'}]}
Year: 1959
DOI: 10.7907/A9DJ-HB94
Part I: Qualitative Spectroscopic Studies of Heated Salts Behind Shock Fronts:
Experimental studies have been conducted on the type of radiation produced from various materials by means of shock waves. As is to be expected, the observed spectra, which are similar to spark and arc spectra, are strongly dependent upon the shock conditions.
Part II: Quantitative Spectroscopic Studies:
Experimental studies were made to determine whether an estimate of population temperature could be obtained from spectrographic records. These tests suggest that excessive cooling occurs in the shock tube. The data relating to temperature measurement are incomplete.https://thesis.library.caltech.edu/id/eprint/378Combustion Research
https://resolver.caltech.edu/CaltechETD:etd-06282006-143052
Authors: {'items': [{'id': 'Reichenbach-Roy-Earl', 'name': {'family': 'Reichenbach', 'given': 'Roy Earl'}, 'show_email': 'NO'}]}
Year: 1960
DOI: 10.7907/8CB5-TG80
In Part 1 an iterative procedure is described for the solution of nozzle flow problems with one-step, reversible chemical reactions. The efficiency of the method of calculation is illustrated by comparing the results with data obtained through the use of machine computations for the recombination of hydrogen atoms in a deLaval nozzle.
Two topics concerned with droplet burning are considered in Part 2. Droplets of several important propellants, viz., RP-1, UDMH and N2H4, were burnt in air and in oxygen. The (effective) evaporation constants were determined experimentally for these fuels. The second topic involves the determination of the propagation rates and mechanism of propagation of a flame in a one-dimensional array of n-octane droplets. The flame propagation rates were found to be a function of the initial droplet size, of the droplet spacing, and directly of the depth of immersion of the droplet in the hot-gas zone.
Part 3 consists of a study of the effect of an inert diluent on spectral intensity ratios in propane-oxygen-nitrogen flames. Experiments were conducted with inert diluent contents of 50, 60, 70, and 80 percent nitrogen (by mass) and with equivalence ratios of 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6. The spectral intensity ratio was found to be a function not only of the equivalence ratio but also of the percentage of inert diluent. Hence it is not possible, in general, to use spectral intensity ratios as measures of mixture composition, a procedure that has been used erroneously by a number of investigators.https://thesis.library.caltech.edu/id/eprint/2758Part 1. Emissivity Calculations for CO₂. Part 2 Shock Tube f-Number Measurement for OH
https://resolver.caltech.edu/CaltechETD:etd-07052006-080623
Authors: {'items': [{'id': 'Lapp-Marshall', 'name': {'family': 'Lapp', 'given': 'Marshall'}, 'show_email': 'NO'}]}
Year: 1960
DOI: 10.7907/BW2K-2M27
<p>Part 1: A model has been developed for the calculation of total emissivities of polyatomic molecules at elevated temperatures in terms of room temperature measurements and of a few parameters characteristic of the major known regions of emission. The model involves a statistical redistribution of the theoretically available intensities throughout these regions. Using this model, emissivities of CO<sub>2</sub> have been calculated at 600°K for optical depths up to 3 ft-atm which agree with the experimental data of Hottel within 8%. Calculations made at temperatures up to 1750°K for optical depths of 0.1 to 2.0 ft-atm agree with the experimental data within 30%.</p>
<p>It appears that the proposed model for calculating the emissivities of CO<sub>2</sub> constitutes a good approximation at elevated temperatures and that the required parameters have been obtained with fair accuracy from a semi-empirical fit to total emissivity data measured at 300°K. It is apparent that a closer correlation with empirical data could have been obtained if an "optimal adjustment" had been made for the three variable parameters by fitting our theoretical formulae to high-temperature emissivity measurements. However, this "optimal fit" would not constitute as stringent a test of our model as the calculations described in this analysis.</p>
<p>We note that the success of these calculations does not depend upon a fit to Hottel's data at 300°K since (a) we are able to calculate the total emissivity at 300°K with fair accuracy from spectroscopic data and (b) we are able to estimate the parameters required by our model directly from available spectroscopic information. The use of Hottel's data is adopted only as a convenience for this test calculation in order to provide a consistent check on our method of calculating emissivities at elevated temperatures.</p>
<p>Part 2: The f-number for the (0,0)-band of the <sup>2</sup>Σ → <sup>2</sup>Π transitions of OH has been found to be (0.9 ± 0.5) x 10<sup>-3</sup>. A shock tube was used to produce hot gas samples at temperatures from 3300 to 3900°K with equilibrium partial pressures of OH of 0.004 to 0.02 atm. The emission intensities were measured photoelectrically as a function of time behind the reflected shock in a selected spectral interval. These results were then related to the f-number by means of an absolute intensity calibration.</p>
https://thesis.library.caltech.edu/id/eprint/2809Part 1. An Investigation of Relaxation Processes. Part 2. Studies in Combustion
https://resolver.caltech.edu/CaltechETD:etd-10042005-105327
Authors: {'items': [{'id': 'Jacobs-Theodore-Alan', 'name': {'family': 'Jacobs', 'given': 'Theodore Alan'}, 'show_email': 'NO'}]}
Year: 1960
DOI: 10.7907/9YND-DS33
Part 1
I. The rate of the homogeneous thermal decomposition of NH3 in NH3-Ar mixtures has been measured in a shock tube by monitoring the radiation emitted by the NH3 in the 3 micron wavelength region. For the temperature range 2000-3000ºK an apparent activation energy of about 52 Kcal was found.
II. The vibrational relaxation of isothermal, dilute gas mixtures after excitation by an external radiation field has been investigated, leading to a proposed experiment for the measurement of collision transition probabilities.
Part 2
I. A review of recent papers in the field of combustion has been prepared for the 1960 Edition of Annual Reviews of Physical Chemistry.
II. An approximate theoretical performance evaluation for a diverging rocket has been performed. A paper describing the evaluation has been published in Astronautics Acta.https://thesis.library.caltech.edu/id/eprint/3914Gas Emissivities and Radiative Transfer Studies
https://resolver.caltech.edu/CaltechETD:etd-06292006-152959
Authors: {'items': [{'id': 'Olfe-Daniel-Burrhus', 'name': {'family': 'Olfe', 'given': 'Daniel Burrhus'}, 'show_email': 'NO'}]}
Year: 1960
DOI: 10.7907/FZWR-9J22
In Chapter 1 theoretical expressions are derived for the relations between gas absorptivities and emissivities for the limit of zero optical depth and for various models of vibration-rotation bands. Some of the band models for which useful results are obtained are bands with constant average absorption coefficients and well-defined widths, bands composed of non-overlapping spectral lines with dispersion or Doppler contour, and bands composed of randomly distributed lines with dispersion contour. The theoretical formulae are shown to provide a good correlation for the available experimental data on CO2, H2O, and CO.
Representative estimates for the radiant energy emission from the combustion products formed by a burning ammonium perchlorate propellant grain are made in Chapter 2. The listed compilations of data may be used to estimate the radiant heat transfer to the burning propellant surface, as well as the radiant energy loss from the combustion products, since emission and absorption of radiation by the gases in the reaction zone are shown to be negligibly small.
The study in Chapter 3 on radiant energy transfer from non-isothermal molecular emitters with non-overlapping dispersion lines complements earlier work done on overlapping lines and on randomly distributed dispersion lines. In addition to the transparent gas approximation for gases of small optical depth, a "square root" approximation is found to be valid for large optical depths, provided the temperature gradient in the slab of gas nearest to the observer is not too large. These approximations are used to derive explicit expressions for the radiant energy flux from two adjacent isothermal regions at different temperatures.
In Chapter 4, the important equilibrium emission processes in a hydrogen plasma are investigated in the temperature range between 300°K and 10,000°K for pressures up to several hundred atmospheres. It is found that the pressure-induced spectrum of the H2 molecule makes an important emissivity contribution at the lower temperatures (below approximately 4500°K) whereas, at the higher temperatures, the bound-free and free-free transitions of the H ion and the continuum and line spectrum of the H atom are the most important contributors to the emissivity. The problems of the very broad wings of the Lyman a line and of the lowering of the ionization potentials by the fields of the plasma ions are considered.https://thesis.library.caltech.edu/id/eprint/2776I. Quantitative Studies of the N0₂- N₂0₄ System in the Infrared. II. Emission of Diffuse Bands of Sodium Behind Shock Fronts
https://resolver.caltech.edu/CaltechTHESIS:07292011-110936010
Authors: {'items': [{'id': 'Guttman-Andrew', 'name': {'family': 'Guttman', 'given': 'Andrew'}, 'show_email': 'NO'}]}
Year: 1962
DOI: 10.7907/BKS0-GN58
<p>integrated intensities as a function of temperature have been measured for one NO_2 and for four N_2O_4 combination bands in the spectral region from one to five microns. The temperature was varied from 50 to 100°C for the gas-phase studies and from 25 to 100°C for the liquid-phase experiments. In the spectral region from 5 to 15 microns, integrated intensities at 25°C were measured for one NO_2 and for three N_2O_4 fundamental bands. Results from a series of absorption spectra were interpreted in accordance with the Wilson–Wells-Penner-Weber method. Saturated vapors were used in all experiments; the optical depth was varied by using a series of spacers in a specially designed infrared absorption cell capable of handling both liquid and gas. Measured intensities for N_2O_4 combination bands in the liquid and gas phases were compared and found to differ by less than 16% for three out of four combination bands studied; for the fourth band, the observed difference was about 50%. Results for all of the combination bands investigated indicate that the integrated intensities vary approximately as 1/T in the temperature range under consideration.</p>
<p>Absolute intensity data may be used for a spectroscopic determination of the heat of dissociation for gases in chemical equilibrium. For the reaction N_2O_4 -> 2NO_2, we have found the value of ΔH° ,using the temperature dependence of the absorption bands, to be 13.1 Kcal/(mole N_2O_4); this value is in fair agreement with the value of 13.7 Kcal/(mole N_2O_4); obtained by techniques utilizing density measurements.</p>
<p>In Chapter II, shock tube studies are descri.bed of a diffuse emission band, centered near the resonance lines of sodium and attributed to van der Waals molecules Na_2. A small quantity of finely ground sodium salt (e.g., NaCl, NaBr, or Na_2CO_3) was placed at the end of the low-pressure section of a shock tube containing an argon atmosphere. Spectra were recorded photographically with a 1.5 m grating spectrograph.</p>https://thesis.library.caltech.edu/id/eprint/6559Part I. Theoretical Calculations of Equilibrium Infrared Gas Emissivities from Spectroscopic Data. Part II. Representative Radiative Energy Transfer Calculations for Transparent and Optically Dense Media
https://resolver.caltech.edu/CaltechTHESIS:04182012-135901615
Authors: {'items': [{'id': 'Gray-Louise-Dillon', 'name': {'family': 'Gray', 'given': 'Louise Dillon'}, 'show_email': 'NO'}]}
Year: 1963
DOI: 10.7907/79HT-JK40
<p>Part I. Measured data for carbon dioxide emissivities at temperatures up to 1800°K have been correlated by postulating (a) that the effective spectral region widths, in which significant contributions are made to the total emission of radiant energy, increase with temperature and optical depth, and (b) that unknown combination and harmonic bands make contributions to the integrated intensities of selected spectral regions in such a way that the absolute values of the integrated intensities (cm^(-2)atm^(-1) remain invariant with temperature.</p>
<p>Spectral emissivities have been calculated in the infrared for hydrogen chloride to the rigid-rotator harmonic oscillator approximation using the "smeared-out" rotational line model for temperatures of 600 and 2400°K. In the weak-line approximation, this model gives reasonable agreement with numerical calculations. In the strongline approximation, there is quite a large discrepancy, particularly in the P-branch, at 2400°K; much better agreement is obtained if vibration-rotation interaction and anharmonicity terms are included in the calculation.</p>
<p>Equilibrium spectral emissivities have been computed for water vapor by using available low-temperature spectroscopic data. Satisfactory agreement with experimental results at 1111°K is obtained if the nearly symmetric top expressions for integrated intensities are used in conjunction with the just-overlapping line model.</p>
<p>Part II. The general equations of radiative energy transfer are presented. When the absorption coefficients and/ or the gas volume are sufficiently large, the general transport equation can be approximated by the "diffusion approximation". This approximation is applied to a two-phase system consisting of carbon- particles dispersed in a gas. The Rosseland mean absorption coefficients are calculated for spherical carbon particles of 200 and 987 A radius at temperatures of 1000 and 2000°K, and a comparison is made of the relative magnitudes of conductive and radiative heat transfer for this system.</p>
<p>In the special case when scattering may be neglected, and the temperature and pressure of the gas are constant, the transport equation can be integrated for a particular direction. The total radiant energy transfer to any given element of area depends upon geometrical interchange factors. These interchange factors have been evaluated for centrally located areas in cylindrical and conical chambers; simple relations are given for a transparent gas and an optically dense gas. A represei1ative calculation has been carried out for the radiant energy transfer to a centrally-located area element at the plane of intersection of two truncated cones.</p>
https://thesis.library.caltech.edu/id/eprint/6944I. Experimental Spectroscopic Temperature Measurements in the Reflected Wave Region of a Shock Tube Using the OH ²Σ → ²π Band System. II. Shock Tube Measurements of the Absorption Oscillator Strength for the ²Σ → ²π Band System of OH
https://resolver.caltech.edu/CaltechTHESIS:10092012-155504520
Authors: {'items': [{'id': 'Watson-Ronald', 'name': {'family': 'Watson', 'given': 'Ronald'}, 'show_email': 'NO'}]}
Year: 1963
DOI: 10.7907/20T1-5E54
<p>I. Experimental measurements of the population temperature
behind the reflected shock in a shock tube are presented. Emission
from two wavelength intervals of the OH ^2Ʃ → ^2π electronic band
system was measured photoelectrically, the signals observed being
generated by a narrow core of hot gas in the reflected shock region
looking axially up the tube. The ratio of the rate of increase of
intensity with unit increase of optical depth in the two spectral regions
is a unique function of the temperature for a transparent gas. The
linearity of the signal increase with time represents an experimental
verification of the transparency and equilibration of the test gas.</p>
<p>In the temperature range of 3300-4300° K(M_s ~ 4), the
measured spectroscopic temperature was in good agreement with the
calculated equilibrium temperature, the estimated accuracy of the
spectroscopic temperature being ±75°K. A relaxation time of about
25 µsec was observed for the (2,2) and (3,3) vibration bands to reach
statistical equilibrium with the lower (0,0) and (1,1) vibrational levels
in the ^2Ʃ state from which the emission occurred.</p>
<p>II. Previous shock tube measurements of the oscillator strength
of the OH ^2Ʃ → ^2π band system made in this Laboratory^(1) have been
corrected. Light scattering in the absolute intensity calibration has
been eliminated and a continuous flushing technique was used for preparation
and introduction of the water vapor-argon test gas mixture
into the tube. The experimental technique remains essentially the
same as in the earlier studies: hot gas samples at 3100-3500° K were
produced behind the reflected shock and the linear rate of increase of
absolute spectral intensity in the transparent gas region was measured
by monitoring emission from axial observations in the shock tube.</p>
<p>The absorption electronic f-number for the ^2Ʃ → ^2π band
system has been determined from the measurements as (3.9 ± 0.9) x
10^(-3). This value should be compared with Carrington's ^(2) result of
1.4 x 10^(-3) from absorption measurements in flames, and Oldenberg
and Rieke's^(3) value of 1.3 x 10^(-3) and Dyne's ^(4) value of 0.7 x 10^(-3)
from measurements in absorption cells.</p>https://thesis.library.caltech.edu/id/eprint/7232Part I. Chemical Reactions During Flow in Rocket Nozzles. Part II. Gas Discharge Rates Through De Laval Nozzles and the Experimental Determination of Desorption Rates
https://resolver.caltech.edu/CaltechTHESIS:05162012-073100475
Authors: {'items': [{'id': 'Porter-John-William', 'name': {'family': 'Porter', 'given': 'John William'}, 'show_email': 'NO'}]}
Year: 1963
DOI: 10.7907/MYSG-P786
<p>In Part I, some of the important physical ideas that have been used in an analysis of chemical changes in rocket nozzles are reviewed with particular reference to the three-body recombination reaction. Modified forma of the simple near-equilibrium flow criterion developed about 15 years ago are shown to lead to results that are substantially equivalent to estimates derived from a criterion
of Bray. The influence of surface-catalyzed processes on atomic recombination rates in rocket nozzles is considered and found likely to be important in present solid-propellant rocket engines.</p>
<p>In Part II, studies of the effective desorption rates of gases (Ar, He, and CO_2) from sand and from silica gel are described. These rates have been determined experimentally by measuring, as a function of time, the pressure drop in a vessel containing the solids when the gases are allowed to discharge through a small de Laval nozzle. The dependence of the desorption rate on temperature has been investigated. A theoretical expression for the rate of desorption from porous solids has been developed assuming that the overall process is diffusion controlled. The experimentally determined desorption rates of Ar, He, and CO_2 from silica gel have been compared with this theoretical expression.</p>
https://thesis.library.caltech.edu/id/eprint/7035Radiative Transfer and Opacity Calculations
https://resolver.caltech.edu/CaltechETD:etd-12092002-103956
Authors: {'items': [{'id': 'Thomas-Mitchell', 'name': {'family': 'Thomas', 'given': 'Mitchell'}, 'show_email': 'NO'}]}
Year: 1964
DOI: 10.7907/EAA2-7R56
The similarity groups for multicomponent, reacting gas mixtures with radiative energy transport are derived. The resulting relations are used to consider the feasibility of scaling for flow processes with radiative energy transport under highly simplified conditions. Next the scaling parameters are derived for radiant energy emission from isobaric and isothermal gases for arbitrary opacities and various spectral line and molecular band models.
The radiative scaling properties for representative temperature profiles for both collision-broadened and Doppler-broadened line profiles have been found for a spectral line belonging to a molecular vibration-rotational spectral band on the basis of exact numerical calculations. Representative calculations are also given for radiant energy transfer through non-isothermal, high-temperature air.
Scaling parameters for radiant energy emission from isobaric but non-isothermal systems are discussed for arbitrary opacities and various spectral line and molecular band models under the restrictions imposed on the allowed temperature profiles for dispersion and Doppler lines by the Eddington-Barbier approximation. An examination is made of the failure of the Eddington-Barbier approximation in radiative heat transfer for line radiation.
The relative importance of thermal conduction and radiation in heated air is specified through the use of the pertinent similarity group. Finally, a procedure is given that may be used to obtain approximate continuum opacity estimates in polyelectronic plasmas.https://thesis.library.caltech.edu/id/eprint/4888Part I. Radiative Transfer Studies and Opacity Calculations for Heated Gases. Part II. Absolute Intensity Measurements for the 2.7 µ Band of Water Vapor in a Shock Tube
https://resolver.caltech.edu/CaltechETD:etd-10292002-112946
Authors: {'items': [{'id': 'Patch-Richard-Walker', 'name': {'family': 'Patch', 'given': 'Richard Walker'}, 'show_email': 'NO'}]}
Year: 1964
DOI: 10.7907/G92Q-ED75
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
PART I.
Equations for radiative transfer of energy in hot gases are presented for cases involving absorption, spontaneous emission, induced emission, and isotropic scattering. Application of these equations to energy transfer between two infinite parallel plates and also to energy transfer to the nose cone of a reentry vehicle are reviewed.
The Planck and Rosseland mean free paths for radiation are derived. It is shown that the treatments by Nachbar and Simon can be combined to give the continuity, momentum, and energy equations for a reacting, multicomponent gas mixture with radiative energy transfer. The resulting equations are then nondimensionalized. The coupling of radiation and convection in detached shock layers is reviewed.
A simplified method for calculating spectral absorption coefficients for electronic bands of diatomic molecules is presented. A simplified method for calculating continuum radiation in plasmas is reviewed.
PART II.
The apparent spectral absorption coefficients of the H2O infrared bands in the vicinity of 2.7 [microns] were measured in a shock tube behind reflected shock waves in an H20-Ar mixture.
By interrupting an infrared beam at a 60 kc rate and projecting this beam across the shock tube to a monochromator, it was possible to simultaneously measure both emission and absorption of H2O at 1000[degrees]K. The spectral absorption coefficients obtained from emission measurements averaged 9.8% higher than absorption coefficients obtained from absorption measurements, probably due to experimental errors (smaller than usually encountered in shock tube measurements). At 1933[degrees]K experimental difficulties precluded simultaneous measurement of infrared emission and absorption, so measurements were restricted to emission.
The apparent absorption coefficients were integrated to give the integrated absorption coefficients for the collections of bands near 2.7[microns]. Integrated absorption coefficients were 49.8 cm[superscript -2] atm[superscript -1], 54.7 cm[superscript -2] atm[superscript -1], and 31.6 cm[superscript -2] atm[superscript -1] for absorption at 1000[degrees]K, emission at 1000[degrees]K, and emission at 1933[degrees]K, respectively. The two values at 1000[degrees]K were in good agreement with those of Goldstein, who made no measurements above this temperature.
Photographic materials on pp. 100, 107, 111, 123, and 128 are essential and will not reproduce clearly on Xerox copies. Photographic copies should be ordered.https://thesis.library.caltech.edu/id/eprint/4294Part I. Measurement of gf-Values for Singly Ionized Chromium Using the Reflected Wave Region of a Shock Tube. Part II. Experimental Investigation of the Approach to Equilibrium Ionization and Electronic Excitation in Shock-Heated Mixtures of Chromium and Argon. Part III. Approximate Spectral Absorption Coefficient Calculations for Electronic Band Systems Belonging to Diatomic Molecules
https://resolver.caltech.edu/CaltechETD:etd-10042002-101246
Authors: {'items': [{'id': 'Shackleford-William-Lewis', 'name': {'family': 'Shackleford', 'given': 'William Lewis'}, 'show_email': 'NO'}]}
Year: 1964
DOI: 10.7907/RAAH-J388
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
Part I.
Absolute gf-values for 21 lines of singly ionized chromium (Cr II) in the spectral region 3118-4559 [angstroms] are presented. Mixtures of Cr(CO)[subscript 6] and argon, heated by reflected shock waves to temperatures in the range 7920[degrees]K to 8730[degrees]K, were used to measure the emission intensity of ionized chromium lines. A three inch diameter shock tube was employed, with the light being observed along the shock tube axis in order to observe directly the curve of growth of each spectral line. The emitted intensities observed were converted to gf-values by means of a comparison with a calibrated tungsten strip lamp. Results are compared with values obtained from arc spectra by Corliss and Bozman[superscript 1] at the National Bureau of Standards. In general, our results are a factor of 9 below the latter measurements. Possible reasons for this discrepancy are discussed.
Part II.
An experimental investigation of the approach to equilibrium ionization and electronic excitation for chromium behind shock waves in Cr(CO)[subscript 6]-argon mixtures is described. Mixtures composed of from 0.0043% to 0.036%o Cr(CO)[subscript 6] were heated by reflected shock waves to temperatures between 6170[degrees]K and 8600[degrees]K, and the emission from excited states of Cr I and Cr II was simultaneously measured by photoelectric means with a time resolution of about 3 microseconds. Relaxation toward equilibrium ionization and excited state population was observed to occur within from 12 to 60 microseconds, depending upon the temperature and chromium concentration behind the reflected shock.
In measurements in which equilibrium ionization is 95% or more, the populations of excited states of Cr I show a pronounced "overshoot" as these states become populated before ionization has depleted the supply of neutral chromium. From a study of the relaxation of Cr I and Cr II upper state populations, it is concluded that ionization proceeds by a multistep autocatalytic process dominated by collisions between chromium atoms and electrons released in prior ionization of chromium. The dependence of the relaxation rates upon the temperature behind the reflected shock wave and upon the concentration of chromium was determined. If it is assumed that the electron and atom temperatures did not differ appreciably during the relaxation period, the variation in the relaxation rate with temperature indicates a 3.1 [plus or minus] 0.3 ev activation energy for chromium ionization, which is significantly less than the ionization potential (6.74 ev).
A simplified reaction mechanism is proposed which qualitatively explains the observed relaxation behavior of Cr I and Cr II.
Part III.
The spectral absorption coefficients in electronic band systems of diatomic emitters have been computed in the past by models that may be described as "the just overlapping line model" and a model "utilizing a smeared out rotational structure". Although the basic relations are obtained by utilizing somewhat different physical arguments, the resulting equations are, in fact, identical.
Spectral absorption coefficients have been calculated for the NO [...]-bands at 2000[degrees]K by using the approximate theoretical relations. The calculated results are in good agreement with estimates derived by numerical calculations in which, however, the absorption coefficient data were averaged over intervals of 2000 cm.[superscript -1].https://thesis.library.caltech.edu/id/eprint/3891Quantitative Spectroscopic Studies on the Infrared Absorption by Water Vapor and Liquid Water
https://resolver.caltech.edu/CaltechETD:etd-09182002-095900
Authors: {'items': [{'id': 'Goldstein-Robert', 'name': {'family': 'Goldstein', 'given': 'Robert'}, 'show_email': 'NO'}]}
Year: 1964
DOI: 10.7907/5NW0-JM56
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
Measurements have been made of the integrated intensities and spectral absorption coefficients of water vapor in the 1.38[micron], 1,87[micron], 2.7[micron], and 6.3[micron] regions at temperatures up to [...], using sufficient self-broadening to remove the rotational fine structure. The experiments were performed in a specially designed, isothermal high-pressure absorption cell supplied with vapor from a liquid water reservoir submerged in a constant temperature oil bath.
In addition, theoretical calculations of the spectral absorption coefficients of water vapor at elevated temperatures have been performed using a just-overlapping line model and the results have been compared with the experimental data.
The spectral absorption coefficients of liquid water have been measured in the wave number regions from 2200 to 3000 cm[superscript -1] and from 3700 to 7600 cm[superscript -1] at temperatures of 27, 89, 159, and 209[degrees]C. From these data, the integrated intensities of the absorption bands at 1.45[microns] and 1.93[microns] have been determined. The experimental data have also been used, in a highly simplified analysis, for the determination of hydrogen bonding in liquid water on the assumption of clusters containing only zero, one or two hydrogen bonds per molecule.
The change in the infrared absorption of gaseous and liquid water has been further investigated by measuring the transmission of infrared radiation through equal optical depths of liquid water and of water vapor near the limits of saturation.https://thesis.library.caltech.edu/id/eprint/3606