Inlet Design Considerations for a Liquid-Hydrogen Pump

Abstract

The use of liquid hydrogen as a fuel for rocket engine powered vehicles has been considered for several years because of its improved performance potential. The unusually low temperature of liquid hydrogen makes it unique from other propellants commonly used in the rocket engine industry. Because of its low temperature in comparison with its normal surroundings, liquid hydrogen will nearly always be boiling in the supply tank due to heat leakage unless special precautions are taken. In rocket engine powered vehicle applications, subcooling could be accomplished by pressurizing the supply tank with gaseous hydrogen or helium to a pressure greater than that corresponding to the vapor pressure of the liquid. This is a transient phenomenon, however, because the temperature rise in the liquid due to heat leakage soon nullifies the subcooling effect of the pressure. Subsequent increases in tank pressure will maintain the subcooling with the added penalty of a continuously or intermittently increasing tank pressure.