Comparison of the Dynamic Characteristics of Electric Pump and Pressure-fed Systems for Space Engines

Electric pump system in the space engines has been paid more and more attention in the world because of its high efficiency, convenient regulation and simple structure. In this study, the engine start-up process and combined operating process of a pressure-fed propulsion system with a modified electric pump propulsion system for an orbiter were compared. The Centralized Parameter Method and the Stepwise Parameter Method were used for modeling. The results show that the electric pump system provides significant performance improvements over the conventional pressure-fed system in the area of orbit-control engines and attitude control engines. During engine start-up, the electric pump system stabilizes the propellant feed faster and improves the reliability of the feed lines. During combined condition, the electric pump system significantly reduces the requirements on the components of gas line. It requires approximately 1/10 of the cylinder pressure and 1/6 of the helium consumption of a pressure-fed system to perform the same conditions. Moreover, it reduces the tank pressure and enables quicker and more accurate changes of conditions.