Solid fuel ramjets (SFRJ) are known for their operational simplicity and high specific impulse. The performance of the SFRJ propulsion system is directly tied to the energy density and combustion behavior of the fuel....Solid fuel ramjets (SFRJ) are known for their operational simplicity and high specific impulse. The performance of the SFRJ propulsion system is directly tied to the energy density and combustion behavior of the fuel. A typical solid fuel used in a ramjet application is a collection of metal particles suspended in a polymeric binder. Boron is the ubiquitous candidate when considering metal additives for fuels due to an impressive 122.5 kJ/cm3 energy density. However, boron requires long residence times in combustors due to its high melting and boiling points. Magnesium appears to be a natural complement to boron;while possessing a lower energy density (42.1 kJ/cm3), it burns with a high flame temperature and readily reacts in combustion with a low melting point. In this study, several HTPB–boron–magnesium fuels are studied on a small scale to evaluate performance for ramjet application. Holography experiments are conducted, as well as laser ignition tests, to study particle behavior just above the fuel surface. Small, center-perforated fuel grains are examined in a direct-connect SFRJ test stand configuration to measure ignition temperatures and performance parameters. Combustion efficiency of the HTPB–boron–magnesium fuel is found to significantly increase for one of the fuels studied.展开更多
A wide variety of hydroxyl-terminated polybutadiene(HTPB)based fuels areexperimentally assessed in anaerobic reaction.In this study HTPB pyrolysis is investigatedusing a CO laser as the energy source.The formulation o...A wide variety of hydroxyl-terminated polybutadiene(HTPB)based fuels areexperimentally assessed in anaerobic reaction.In this study HTPB pyrolysis is investigatedusing a CO laser as the energy source.The formulation of the solid fuel samples issystematically changed to isolate the effects of carbon black,metal fuel additives,and smallamounts of oxidizer.In addition,chemical changes to the fuels including curative type andbase polymer are varied.Rates of pyrolysis reaction are reported for a wide range of solid fuelsapplicable to ramjet application.Processes involving the sintering together of metal particles,accumulation of carbon black,and formation of a melt layer are found to affect the reactionrate.It is determined that the surface composition is the most influential factor influencing theregression rate of HTPB based fuels.展开更多
基金The authors wish to thank Cliff Bedford and ONR Code 35 for funding under contract number N0001416WX01613.Additionally,the authors thank the NAVAIR ILIR program,managed at by the N-STAR program(Naval Research–Science and Technology for America's Readiness)administered by Lee Cambrea.
文摘Solid fuel ramjets (SFRJ) are known for their operational simplicity and high specific impulse. The performance of the SFRJ propulsion system is directly tied to the energy density and combustion behavior of the fuel. A typical solid fuel used in a ramjet application is a collection of metal particles suspended in a polymeric binder. Boron is the ubiquitous candidate when considering metal additives for fuels due to an impressive 122.5 kJ/cm3 energy density. However, boron requires long residence times in combustors due to its high melting and boiling points. Magnesium appears to be a natural complement to boron;while possessing a lower energy density (42.1 kJ/cm3), it burns with a high flame temperature and readily reacts in combustion with a low melting point. In this study, several HTPB–boron–magnesium fuels are studied on a small scale to evaluate performance for ramjet application. Holography experiments are conducted, as well as laser ignition tests, to study particle behavior just above the fuel surface. Small, center-perforated fuel grains are examined in a direct-connect SFRJ test stand configuration to measure ignition temperatures and performance parameters. Combustion efficiency of the HTPB–boron–magnesium fuel is found to significantly increase for one of the fuels studied.
文摘A wide variety of hydroxyl-terminated polybutadiene(HTPB)based fuels areexperimentally assessed in anaerobic reaction.In this study HTPB pyrolysis is investigatedusing a CO laser as the energy source.The formulation of the solid fuel samples issystematically changed to isolate the effects of carbon black,metal fuel additives,and smallamounts of oxidizer.In addition,chemical changes to the fuels including curative type andbase polymer are varied.Rates of pyrolysis reaction are reported for a wide range of solid fuelsapplicable to ramjet application.Processes involving the sintering together of metal particles,accumulation of carbon black,and formation of a melt layer are found to affect the reactionrate.It is determined that the surface composition is the most influential factor influencing theregression rate of HTPB based fuels.
