L Caveny | Georgia Institute of Technology (original) (raw)
Papers by L Caveny
Proceedings of 17th International Symposium on Combustion August 1978, pp. 1453-1461, 1978
Aluminum powders added to conventional rocket propellants burn either as single particles or aggl... more Aluminum powders added to conventional rocket propellants burn either as single particles
or agglomerates which contain hundreds or even thousands of the original particles. Combustion efficiency and acoustic stability characteristics are very dependent on the final A1/ A1203
particle size injected into the chamber flowfield. High-speed photographs of burning homogeneous propellants provided data on agglomeration size and visualization of the flow processes
as a function of pressure (1 to 10 MPa), initial particle size (5 to 100 /im), and aluminum
mass fraction (0.1 to 13%). Photomicrographs of extinguished surfaces revealed the importance
of particle accumulation in a thin mobile reaction layer adjacent to the burning surface.
A model was developed that interpreted data and observations from several sources. The
model accounts for accumulation of aluminum particles in the mobile reaction layer, retention
of particles by surface tension forces, melting, and ignition at the surface. The following
agglomeration and particle behavior items are categorized: decreasing agglomerate size with
increasing pressure, minimum mass loading required for agglomeration, prominent agglomeration for particles with diameters less than the reaction layer thickness, and sharply reduced
agglomeration for larger particles. The model provides an approach for controlling and
interpreting agglomerate size behavior.
AIAA JOURNAL, Vol. 16, No. 7, July 1978, pp. 736-739, 1978
Combustion and agglomeration processes of aluminum particles emitted from the surface of an alumi... more Combustion and agglomeration processes of aluminum particles emitted from the surface of an aluminized
double-base propellant (NC/TMETN) were studied under rocket motor, crossflow conditions. High-speed color
photographs (— 2000 frames/s) were taken of burning Al/Al203 agglomerates forming on the surface, moving
along the surface, and entering the flowfield. As an example, a propellant containing 6-/zm Al burning at 7 MPa
and 6 m/s crossflow produced a mean agglomerate size of about 250 /um. Analysis of size distributions of the
agglomerates leaving the surface revealed that the following parameters decrease with increasing pressure:
collision frequency on the surface, the agglomerate stay time on the surface, and mean agglomerate size. Increasing the crossflow velocity decreased the mean agglomerate size. The propellants which contained the large
aluminum particles (50 /*m vs 6 /um) burned without the aluminum igniting or agglomerating on the surface.
Symposium (International) on Combustion, 1982
ABSTRACT Very high shearing flows of high pressure, hot gases over metal surfaces produce chemica... more ABSTRACT Very high shearing flows of high pressure, hot gases over metal surfaces produce chemicaland physical gas metal interactions (i.e., combustion, oxidation, and melting) which differ markedly from those produced by quiescent and low flow conditions. Such situations are encountered, e.g., in gun barrels, turbines, vents and nozzles, and can result in severe erosion of the metal. An analytical model hypothesizes that the high shearing flows limit the build-up of protective oxide layers on the surface, thus exposing the metal to a more direct chemical attack and establishing heterogeneous surface reactions even in cases in which the metal would burn in the gas phase under quiescent atmosphere. When melting is involved, metal mass loss is mainly due to melt generation and removal, which depend on surface heating rate. Surface heating is greatly enhanced by exothermic surface reactions. The existence of a melt layer on the solid surface lowers the heat transfer to the unmelted metal. Comparisons of calculated results to experimental results, in which steel was subjected to short pulses (∼2 ms) of high pressure (∼350 MPa) hot (∼2500 K) air flow, exhibit good agreement and reveal that gas phase combustion is unlikely, the reaction rate is diffusion controlled, melting rates enhanced by chemical heating can exceed direct chemical consumption rate three-fold, and a few micrometer thick melt layer reduces the calculated mass loss by about 13%.
Symposium (International) on Combustion, 1979
ABSTRACT Aluminum powders added to conventional rocket propellants burn either as single particle... more ABSTRACT Aluminum powders added to conventional rocket propellants burn either as single particles or agglomerates which contain hundreds or even thousands of the original particles. Combustion efficiency and acoustic stability characteristics are very dependent on the final Al/Al2O3 particle size injected into the chamber flowfield. High-speed photographs of burning homogeneous propellants provided data on agglomeration size and visualization of the flow processes as a function of pressure (1 to 10 MPa), initial particle size (5 to 100 μm), and aluminum mass fraction (0.1 to 13%). Photomicrographs of extinguished surfaces revealed the importance of particle accumulation in a thin mobile reaction layer adjacent to the burning surface. A model was developed that interpreted data and observations from several sources. The model accounts for accumulation of aluminum particles in the mobile reaction layer, retention of particles by surface tension forces, melting, and ignition at the surface. The following agglomeration and particle behavior items are categorized: decreasing agglomerate size with increasing pressure, minimum mass loading required for agglomeration, prominent agglomeration for particles with diameters less than the reaction layer thickness, and sharply reduced agglomeration for larger particles. The model provides an approach for controlling and interpreting agglomerate size behavior.
AIAA Journal, 1981
A methodology centered around the forced longitudinal wave (FLW) motor is being developed to inve... more A methodology centered around the forced longitudinal wave (FLW) motor is being developed to investigate
dynamic responses of rocket motors. The FLW motor establishes periodic longitudinal pressure and velocity
oscillations in solid propellant rocket chambers. A linear analysis was developed to study propellant pressureand velocity-coupled responses using dynamic pressure measurements at several locations in a motor. The
analysis uses pressure amplitude and phase measurements. Variations in the propellant reponses are shown to
produce measurable changes in the calculated oscillating pressures with velocity-coupled responses showing the
greatest promise for determination from experimental data. Experimentally deduced velocity-coupled response
functions are examined over a frequency range centered around the chamber fundamental mode for a range of
interior flowfields and chamber pressures for 86OJoAP-140J0HTPB propellants.
Research was directed at making measurements of oscillatory velocities In propane/air and solid p... more Research was directed at making measurements of oscillatory velocities In propane/air and solid propellant flames using laser Doppler velocimetry (LDV) instrumentation. Combustors were developed to impose con trolled periodic pressure disturbances on burning solid propellants and to excite a propane/air flame. A tracking system was developed to maintain the LDV control volume at a fixed position above the regressing propellant surface so that a large number (over 10,000) of velocity realizations could be recorded. The research demon strated that unsteady velocities (up to 1000 Hz) could be measured for propane/air flames seeded with micron. sized particles and for solid propellant flames. The simultaneous velocity and pressure measurements were used to obtain acoustic admittances over a range of excitation frequencies, amplitudes, and pressures.
47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2011
Martin Summerfield (1916-1996) pioneered in rocket propulsion and combustion research. He had key... more Martin Summerfield (1916-1996) pioneered in rocket propulsion and combustion research. He had key roles in transforming the American Rocket Society into a leading professional organization and a precursor to the American Institute of Aeronautics and Astronautics (AIAA). In 1940, he began his career as a California Institute of Technology (Caltech) graduate student working for Theodore von Kármán on the Army Air Corps Jet Propulsion Project to demonstrate the first US jet-assisted takeoff (JATO) units in 1942. From 1942 to 1949, as a founder of Aerojet Engineering Corporation and as a manager at Caltech's Jet Propulsion Laboratory, he led development of liquid-propellant propulsion and planning for long-range missiles. The JPL liquid propulsion contributions are described in the context of the propulsion accomplishments of Goddard and the German teams led by von Braun and Walter. In 1949, Summerfield came to Princeton University as Editor of the Princeton Series; in 1950, he received his first faculty appointment. He went on to establish a renowned solid-rocket propulsion and combustion laboratory. Following his retirement from Princeton University in 1978, he devoted more time to his company, Princeton Combustion Research Laboratory. This paper focuses on his Princeton University laboratory and his graduate students. Research in his laboratory yielded fifty dissertations and theses; all include aspects of combustion. Anecdotes are included to illustrate how Professor Summerfield's experiences gave him keen insights into preparing his students for practical problems and hardware.
Journal of Heat Transfer, 1981
Experimental results on the role of water vapor in the mass loss mechanism of steel by hot, high ... more Experimental results on the role of water vapor in the mass loss mechanism of steel by hot, high pressure flows are described and interpreted in terms of a surface reaction model. Situations in which highly transient heat transfer and chemical interactions at the gas-metal interface produce erosion of the surface occur in a variety of systems, e.g., gun barrels, gas turbines, vents, nozzles, and furnaces. This research is directed at conditions in which the metal surface temperature remains below the melting point and mass loss is the result of chemical attack. The rate of reaction depends on the unsteady pressure and surface temperature. The study reveals that in high shearing flows, when the build-up of oxide protective layer is limited, surface chemical attack of the steel by water vapor can be the main erosion source in combustion gas atmospheres, and the process is controlled mainly by turbulent transport phenomena.
AIAA Journal, 1979
Aluminized propdlrnts often p~uce large AI/AIP03 qglomentes which burn slowly compwd to rocket mo... more Aluminized propdlrnts often p~uce large AI/AIP03 qglomentes which burn slowly compwd to rocket motor stay times. Two-phase llow velocity lags in the nozzle cause breakup of suffickntly Iargt aggIomentcs and thereby permit msonaMe combustion eftickacks to be achieved. High-spd photogmphs of the agglomerate pmxsses in a windowed rocket motor were used to obtain data on bmkup as a function of agglomerate size and two-phase flow vclocitics. The breakup process produces a cloud of much smaller droplets. A cemlation of the minimum qgglomerate size for bnakup was obtained in terms of the do of AI/AI2O3 surface tension and shear forces. Generally, agglomerotr: breakup occurs when the Weber number exceeds the range of 20 to 30. Nomenclature C,, = drag coefficient d,, = diameter of agglomerate, m F = drag force on agglomerate, N M = Mach number Red = Reynolds number based on diameter of agglomerate u = velocity, m/s We = Weber number p = density, kg/m rr = surface tension, N/m Subscripts performance compared with the theoretical would occur. Studies of the overall combustion efficiency of aluminized propellants burning in rocket motors reveal the performance losses due to incomplete combustion of aluminum and particle lag. It has been hypothesized that the two-phase flow processes in the nozzle produce breakup of sufficiently large agglomerates and thereby permit reasonable combustion efficiencies to be achieved. However, until now, direct observations of agglomerate breakup dnder rocket motor nozzle flow conditions did ,- ot exist.
AIAA Journal, 1978
Combustion and agglomeration processes of aluminum particles emitted from the surface of an alumi... more Combustion and agglomeration processes of aluminum particles emitted from the surface of an aluminized double-base propellant (NC/TMETN) were studied under rocket motor, crossflow conditions. High-speed color photographs (-2000 frames/s) were taken of burning AI/AI2O3 agglomerates forming on the surface, moving along the surface, and entering the flowfield. As an example, a propellant containing 6-^m Al burning at 7 MPa and 6 m/s crossflow produced a mean agglomerate size of about 250 ^m. Analysis of size distributions of the agglomerates leaving the surface revealed that the following parameters decrease with increasing pressure: collision frequency on the surface, the agglomerate stay time on the surface, and mean agglomerate size. Increasing the crossflow velocity decreased the mean agglomerate size. The propellants which contained the large aluminum particles (50 /*m vs 6 j*m) burned without the aluminum igniting or agglomerating on the surface.
Journal of Propulsion and Power, 2003
This study continues the experimental investigation of the thermal and chemical erosion character... more This study continues the experimental investigation of the thermal and chemical erosion characteristics of steel alloys which were begun under Contract DAAG46-72-C-0078. The high pressure (approx. 3 kbars) and high temperature (approx. 3000 K) environment to which the steel specimens are subjected is produced by a ballistic compressor and by a solid propellant combustor. Equilibrium thermochemical calculations of the possible reactions indicate that the most probable reaction products are oxides, nitrides, carbides, and carbonyls, in that order. The cause of surface cracks was found to be thermal and not relatable to the degree and severity of erosion. Erosion tests of the pure metals used as alloying elements revealed that molybdenum has the highest erosion resistance, followed by nickel. There is no evidence that alloying elements alter the chemical interaction between oxygen and iron. SEM studies revealed that, when an accumulation of oxide scale occurs with successive firings, o...
15th Joint Propulsion Conference, 1979
The findings in this report are not to be construed as an official Department of the Army positio... more The findings in this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.
rate data for several lots of Ml, M26, M30, and HMX polyurethane propellants are presented. Burni... more rate data for several lots of Ml, M26, M30, and HMX polyurethane propellants are presented. Burning rate consistency of M26 doublebase propellant is good, i.e., coefficient of variation = 1%. However, the burning rate variability of single base propellants is dependent on the dispersion of fibrous nitrocellulose. Burning rate exponents obtained under steady state burning conditions are about 20% higher than recent closed chamber results. The results from a large number of specimens tested during the study demonstrate that the apparatus and data analysis techniques can be efficiently used under production situations.
8th Joint Propulsion Specialist Conference, 1972
Parametric studies have shown that the induction period and flame spreading duration are greatly ... more Parametric studies have shown that the induction period and flame spreading duration are greatly affected by the igniter mass flow rate and gas temperature, the correlation for heat-transfer coefficient, Ap/At between 1.06 and 1.5, and uncertainty in the thermal conductivity and ignition temperature of the propelcant. The maximum chamber pressure and pressurization rate are affected by the igniter mass flow rate, burning surface-to-throat area ratio, burning rate law, Ap/At, and axial distance along the port. The analysis enables starting thrust transient prediction and control by proper calculation of the stagnation pressure at the nozzle entrance. An important area for future work is to extend this analysis to segmented motors. The formulation of the analytical model allows an easy extension of the analysis to various types of solid propellants and operational motor configurations. v
12th Propulsion Conference, 1976
JOURNAL OF PROPULSION AND POWER Vol. 19, No. 6, November–December 2003, 2003
The accomplishments of the U.S. solid rocket community are chronicled via discussion of ten enabl... more The accomplishments of the U.S. solid rocket community are chronicled via discussion of ten enabling technologies and the people and organizations that produced them. This approach demonstrates the vibrant and advancing nature of solid rocket technology; to call it a history implies a recollection of something finished. The paper addresses key events and technology in a substantive manner by defining the major concepts (e.g., Pyrogen igniter, large case-bonded grains, composite cases, Flexseal-TVC, extendible exit cone), new materials (e.g., carbon–carbon, Kevlar®) and the advances in tools (e.g., hazard tests, thermochemistry tables, and standard performance prediction packages) that were central to technological advancement. The paper chronicles how these keys enabled incredible advancements ranging from the 260-in. space booster to miniature multi-axis divert propulsion systems. Space limitations prevent discussion of many interesting concepts tested but not fielded. In view of the companion paper by Alain Davenas, “The Development of Modern Solid Propellants” in this issue, this paper focuses on hardware advancements.
3rd Propulsion Joint Specialist Conference, 1967
Proceedings of 17th International Symposium on Combustion August 1978, pp. 1453-1461, 1978
Aluminum powders added to conventional rocket propellants burn either as single particles or aggl... more Aluminum powders added to conventional rocket propellants burn either as single particles
or agglomerates which contain hundreds or even thousands of the original particles. Combustion efficiency and acoustic stability characteristics are very dependent on the final A1/ A1203
particle size injected into the chamber flowfield. High-speed photographs of burning homogeneous propellants provided data on agglomeration size and visualization of the flow processes
as a function of pressure (1 to 10 MPa), initial particle size (5 to 100 /im), and aluminum
mass fraction (0.1 to 13%). Photomicrographs of extinguished surfaces revealed the importance
of particle accumulation in a thin mobile reaction layer adjacent to the burning surface.
A model was developed that interpreted data and observations from several sources. The
model accounts for accumulation of aluminum particles in the mobile reaction layer, retention
of particles by surface tension forces, melting, and ignition at the surface. The following
agglomeration and particle behavior items are categorized: decreasing agglomerate size with
increasing pressure, minimum mass loading required for agglomeration, prominent agglomeration for particles with diameters less than the reaction layer thickness, and sharply reduced
agglomeration for larger particles. The model provides an approach for controlling and
interpreting agglomerate size behavior.
AIAA JOURNAL, Vol. 16, No. 7, July 1978, pp. 736-739, 1978
Combustion and agglomeration processes of aluminum particles emitted from the surface of an alumi... more Combustion and agglomeration processes of aluminum particles emitted from the surface of an aluminized
double-base propellant (NC/TMETN) were studied under rocket motor, crossflow conditions. High-speed color
photographs (— 2000 frames/s) were taken of burning Al/Al203 agglomerates forming on the surface, moving
along the surface, and entering the flowfield. As an example, a propellant containing 6-/zm Al burning at 7 MPa
and 6 m/s crossflow produced a mean agglomerate size of about 250 /um. Analysis of size distributions of the
agglomerates leaving the surface revealed that the following parameters decrease with increasing pressure:
collision frequency on the surface, the agglomerate stay time on the surface, and mean agglomerate size. Increasing the crossflow velocity decreased the mean agglomerate size. The propellants which contained the large
aluminum particles (50 /*m vs 6 /um) burned without the aluminum igniting or agglomerating on the surface.
Symposium (International) on Combustion, 1982
ABSTRACT Very high shearing flows of high pressure, hot gases over metal surfaces produce chemica... more ABSTRACT Very high shearing flows of high pressure, hot gases over metal surfaces produce chemicaland physical gas metal interactions (i.e., combustion, oxidation, and melting) which differ markedly from those produced by quiescent and low flow conditions. Such situations are encountered, e.g., in gun barrels, turbines, vents and nozzles, and can result in severe erosion of the metal. An analytical model hypothesizes that the high shearing flows limit the build-up of protective oxide layers on the surface, thus exposing the metal to a more direct chemical attack and establishing heterogeneous surface reactions even in cases in which the metal would burn in the gas phase under quiescent atmosphere. When melting is involved, metal mass loss is mainly due to melt generation and removal, which depend on surface heating rate. Surface heating is greatly enhanced by exothermic surface reactions. The existence of a melt layer on the solid surface lowers the heat transfer to the unmelted metal. Comparisons of calculated results to experimental results, in which steel was subjected to short pulses (∼2 ms) of high pressure (∼350 MPa) hot (∼2500 K) air flow, exhibit good agreement and reveal that gas phase combustion is unlikely, the reaction rate is diffusion controlled, melting rates enhanced by chemical heating can exceed direct chemical consumption rate three-fold, and a few micrometer thick melt layer reduces the calculated mass loss by about 13%.
Symposium (International) on Combustion, 1979
ABSTRACT Aluminum powders added to conventional rocket propellants burn either as single particle... more ABSTRACT Aluminum powders added to conventional rocket propellants burn either as single particles or agglomerates which contain hundreds or even thousands of the original particles. Combustion efficiency and acoustic stability characteristics are very dependent on the final Al/Al2O3 particle size injected into the chamber flowfield. High-speed photographs of burning homogeneous propellants provided data on agglomeration size and visualization of the flow processes as a function of pressure (1 to 10 MPa), initial particle size (5 to 100 μm), and aluminum mass fraction (0.1 to 13%). Photomicrographs of extinguished surfaces revealed the importance of particle accumulation in a thin mobile reaction layer adjacent to the burning surface. A model was developed that interpreted data and observations from several sources. The model accounts for accumulation of aluminum particles in the mobile reaction layer, retention of particles by surface tension forces, melting, and ignition at the surface. The following agglomeration and particle behavior items are categorized: decreasing agglomerate size with increasing pressure, minimum mass loading required for agglomeration, prominent agglomeration for particles with diameters less than the reaction layer thickness, and sharply reduced agglomeration for larger particles. The model provides an approach for controlling and interpreting agglomerate size behavior.
AIAA Journal, 1981
A methodology centered around the forced longitudinal wave (FLW) motor is being developed to inve... more A methodology centered around the forced longitudinal wave (FLW) motor is being developed to investigate
dynamic responses of rocket motors. The FLW motor establishes periodic longitudinal pressure and velocity
oscillations in solid propellant rocket chambers. A linear analysis was developed to study propellant pressureand velocity-coupled responses using dynamic pressure measurements at several locations in a motor. The
analysis uses pressure amplitude and phase measurements. Variations in the propellant reponses are shown to
produce measurable changes in the calculated oscillating pressures with velocity-coupled responses showing the
greatest promise for determination from experimental data. Experimentally deduced velocity-coupled response
functions are examined over a frequency range centered around the chamber fundamental mode for a range of
interior flowfields and chamber pressures for 86OJoAP-140J0HTPB propellants.
Research was directed at making measurements of oscillatory velocities In propane/air and solid p... more Research was directed at making measurements of oscillatory velocities In propane/air and solid propellant flames using laser Doppler velocimetry (LDV) instrumentation. Combustors were developed to impose con trolled periodic pressure disturbances on burning solid propellants and to excite a propane/air flame. A tracking system was developed to maintain the LDV control volume at a fixed position above the regressing propellant surface so that a large number (over 10,000) of velocity realizations could be recorded. The research demon strated that unsteady velocities (up to 1000 Hz) could be measured for propane/air flames seeded with micron. sized particles and for solid propellant flames. The simultaneous velocity and pressure measurements were used to obtain acoustic admittances over a range of excitation frequencies, amplitudes, and pressures.
47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2011
Martin Summerfield (1916-1996) pioneered in rocket propulsion and combustion research. He had key... more Martin Summerfield (1916-1996) pioneered in rocket propulsion and combustion research. He had key roles in transforming the American Rocket Society into a leading professional organization and a precursor to the American Institute of Aeronautics and Astronautics (AIAA). In 1940, he began his career as a California Institute of Technology (Caltech) graduate student working for Theodore von Kármán on the Army Air Corps Jet Propulsion Project to demonstrate the first US jet-assisted takeoff (JATO) units in 1942. From 1942 to 1949, as a founder of Aerojet Engineering Corporation and as a manager at Caltech's Jet Propulsion Laboratory, he led development of liquid-propellant propulsion and planning for long-range missiles. The JPL liquid propulsion contributions are described in the context of the propulsion accomplishments of Goddard and the German teams led by von Braun and Walter. In 1949, Summerfield came to Princeton University as Editor of the Princeton Series; in 1950, he received his first faculty appointment. He went on to establish a renowned solid-rocket propulsion and combustion laboratory. Following his retirement from Princeton University in 1978, he devoted more time to his company, Princeton Combustion Research Laboratory. This paper focuses on his Princeton University laboratory and his graduate students. Research in his laboratory yielded fifty dissertations and theses; all include aspects of combustion. Anecdotes are included to illustrate how Professor Summerfield's experiences gave him keen insights into preparing his students for practical problems and hardware.
Journal of Heat Transfer, 1981
Experimental results on the role of water vapor in the mass loss mechanism of steel by hot, high ... more Experimental results on the role of water vapor in the mass loss mechanism of steel by hot, high pressure flows are described and interpreted in terms of a surface reaction model. Situations in which highly transient heat transfer and chemical interactions at the gas-metal interface produce erosion of the surface occur in a variety of systems, e.g., gun barrels, gas turbines, vents, nozzles, and furnaces. This research is directed at conditions in which the metal surface temperature remains below the melting point and mass loss is the result of chemical attack. The rate of reaction depends on the unsteady pressure and surface temperature. The study reveals that in high shearing flows, when the build-up of oxide protective layer is limited, surface chemical attack of the steel by water vapor can be the main erosion source in combustion gas atmospheres, and the process is controlled mainly by turbulent transport phenomena.
AIAA Journal, 1979
Aluminized propdlrnts often p~uce large AI/AIP03 qglomentes which burn slowly compwd to rocket mo... more Aluminized propdlrnts often p~uce large AI/AIP03 qglomentes which burn slowly compwd to rocket motor stay times. Two-phase llow velocity lags in the nozzle cause breakup of suffickntly Iargt aggIomentcs and thereby permit msonaMe combustion eftickacks to be achieved. High-spd photogmphs of the agglomerate pmxsses in a windowed rocket motor were used to obtain data on bmkup as a function of agglomerate size and two-phase flow vclocitics. The breakup process produces a cloud of much smaller droplets. A cemlation of the minimum qgglomerate size for bnakup was obtained in terms of the do of AI/AI2O3 surface tension and shear forces. Generally, agglomerotr: breakup occurs when the Weber number exceeds the range of 20 to 30. Nomenclature C,, = drag coefficient d,, = diameter of agglomerate, m F = drag force on agglomerate, N M = Mach number Red = Reynolds number based on diameter of agglomerate u = velocity, m/s We = Weber number p = density, kg/m rr = surface tension, N/m Subscripts performance compared with the theoretical would occur. Studies of the overall combustion efficiency of aluminized propellants burning in rocket motors reveal the performance losses due to incomplete combustion of aluminum and particle lag. It has been hypothesized that the two-phase flow processes in the nozzle produce breakup of sufficiently large agglomerates and thereby permit reasonable combustion efficiencies to be achieved. However, until now, direct observations of agglomerate breakup dnder rocket motor nozzle flow conditions did ,- ot exist.
AIAA Journal, 1978
Combustion and agglomeration processes of aluminum particles emitted from the surface of an alumi... more Combustion and agglomeration processes of aluminum particles emitted from the surface of an aluminized double-base propellant (NC/TMETN) were studied under rocket motor, crossflow conditions. High-speed color photographs (-2000 frames/s) were taken of burning AI/AI2O3 agglomerates forming on the surface, moving along the surface, and entering the flowfield. As an example, a propellant containing 6-^m Al burning at 7 MPa and 6 m/s crossflow produced a mean agglomerate size of about 250 ^m. Analysis of size distributions of the agglomerates leaving the surface revealed that the following parameters decrease with increasing pressure: collision frequency on the surface, the agglomerate stay time on the surface, and mean agglomerate size. Increasing the crossflow velocity decreased the mean agglomerate size. The propellants which contained the large aluminum particles (50 /*m vs 6 j*m) burned without the aluminum igniting or agglomerating on the surface.
Journal of Propulsion and Power, 2003
This study continues the experimental investigation of the thermal and chemical erosion character... more This study continues the experimental investigation of the thermal and chemical erosion characteristics of steel alloys which were begun under Contract DAAG46-72-C-0078. The high pressure (approx. 3 kbars) and high temperature (approx. 3000 K) environment to which the steel specimens are subjected is produced by a ballistic compressor and by a solid propellant combustor. Equilibrium thermochemical calculations of the possible reactions indicate that the most probable reaction products are oxides, nitrides, carbides, and carbonyls, in that order. The cause of surface cracks was found to be thermal and not relatable to the degree and severity of erosion. Erosion tests of the pure metals used as alloying elements revealed that molybdenum has the highest erosion resistance, followed by nickel. There is no evidence that alloying elements alter the chemical interaction between oxygen and iron. SEM studies revealed that, when an accumulation of oxide scale occurs with successive firings, o...
15th Joint Propulsion Conference, 1979
The findings in this report are not to be construed as an official Department of the Army positio... more The findings in this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.
rate data for several lots of Ml, M26, M30, and HMX polyurethane propellants are presented. Burni... more rate data for several lots of Ml, M26, M30, and HMX polyurethane propellants are presented. Burning rate consistency of M26 doublebase propellant is good, i.e., coefficient of variation = 1%. However, the burning rate variability of single base propellants is dependent on the dispersion of fibrous nitrocellulose. Burning rate exponents obtained under steady state burning conditions are about 20% higher than recent closed chamber results. The results from a large number of specimens tested during the study demonstrate that the apparatus and data analysis techniques can be efficiently used under production situations.
8th Joint Propulsion Specialist Conference, 1972
Parametric studies have shown that the induction period and flame spreading duration are greatly ... more Parametric studies have shown that the induction period and flame spreading duration are greatly affected by the igniter mass flow rate and gas temperature, the correlation for heat-transfer coefficient, Ap/At between 1.06 and 1.5, and uncertainty in the thermal conductivity and ignition temperature of the propelcant. The maximum chamber pressure and pressurization rate are affected by the igniter mass flow rate, burning surface-to-throat area ratio, burning rate law, Ap/At, and axial distance along the port. The analysis enables starting thrust transient prediction and control by proper calculation of the stagnation pressure at the nozzle entrance. An important area for future work is to extend this analysis to segmented motors. The formulation of the analytical model allows an easy extension of the analysis to various types of solid propellants and operational motor configurations. v
12th Propulsion Conference, 1976
JOURNAL OF PROPULSION AND POWER Vol. 19, No. 6, November–December 2003, 2003
The accomplishments of the U.S. solid rocket community are chronicled via discussion of ten enabl... more The accomplishments of the U.S. solid rocket community are chronicled via discussion of ten enabling technologies and the people and organizations that produced them. This approach demonstrates the vibrant and advancing nature of solid rocket technology; to call it a history implies a recollection of something finished. The paper addresses key events and technology in a substantive manner by defining the major concepts (e.g., Pyrogen igniter, large case-bonded grains, composite cases, Flexseal-TVC, extendible exit cone), new materials (e.g., carbon–carbon, Kevlar®) and the advances in tools (e.g., hazard tests, thermochemistry tables, and standard performance prediction packages) that were central to technological advancement. The paper chronicles how these keys enabled incredible advancements ranging from the 260-in. space booster to miniature multi-axis divert propulsion systems. Space limitations prevent discussion of many interesting concepts tested but not fielded. In view of the companion paper by Alain Davenas, “The Development of Modern Solid Propellants” in this issue, this paper focuses on hardware advancements.
3rd Propulsion Joint Specialist Conference, 1967