Design and Verification of Electric Pump for Small LOX/Methane Rocket Engine

As the global market for small satellites grows, the demand for small launch vehicles rises as well. In addition, the accelerated technological development of battery and motor have drawn attention to the electric pump cycle for small launch vehicles which utilizes electric motor and battery packs to drive a pump. In this study, a practical design of an electric pump cycle for a 5400 N-class rocket engine is proposed. First, the electric pump with very low specific speed was designed due to limited rotational speed of a commercial motor for cost-effective system. Second, to determine the appropriate discharge angle for very low specific speed pump, two impellers with different discharge angle were designed and verified by numerical and experimental methods. Type A impeller with discharge angle of 10° focusses on achieving high efficiency, while type B impeller with discharge angle of 33° has general geometry. The hydraulic and suction performance of the two impellers was first compared in a cold-water performance test. The hydraulic efficiency of type A impeller was 52.53% and higher than that of type B impeller, 43.28%. Furthermore, type A impeller had higher suction performance than type B impeller; the critical cavitation number of type A impeller was more than 0.07 lower than that of type B impeller. Moreover, the operation of the electric pump under cryogenic environment was verified by performing cryogenic performance tests using liquid nitrogen as simulant.