Cryogenic test bench for the experimental investigation of cryogenic injection in rocket combusters under high-altitude conditions

Abstract

Due to current and future environmental and safety issues in space propulsion, typical propellants for upper stage or satellite rocket engines such as the toxic hydrazine are going to be replaced by green propellants like the combination of liquid oxygen and hydrogen or methane. The injection of that kind of cryogenic fluid into the vacuum atmosphere of space leads to a superheated state, which results in a sudden and eruptive atomization due to flash boiling. For a detailed experimental investigation of superheated cryogenic fluids the new cryogenic test bench M3.3 with a temperature controlled injection system at high-altitude conditions was built at DLR Lampoldshausen. First run-in tests as well as several measurement campaigns with liquid nitrogen as the test fluid showed the performance and suitability of the new test bench for the systematical investigation of cryogenic flash boiling. Besides new insights into the flash boiling process of cryogenic liquids, the experimental data of cryogenic flash boiling generated with this test bench provide a comprehensive database for the validation of numerical models and further numerical investigations.