Survey on key techniques of rocket-based combined-cycle engine in ejector mode

Abstract

Abstract A rocket-based combined-cycle (RBCC) engine synthetically integrates a traditional rocket engine with an airbreathing engine, effectively combining both advantages of high thrust-to-weight ratio and high specific impulse. It has become one of the most efficient propulsion systems for future reusable space transportation vehicles. In engineering practice, the engine performance during ejector mode plays a significant role in determining the efficiency of the whole RBCC propulsion system. This study aims to provide a summary report on the recent research progress on the RBCC engine in ejector mode. Firstly, the basic operating principle of the RBCC ejector mode is introduced and its ideal thermodynamic cycle process is theoretically analyzed. Secondly, the influencing factors on RBCC engine performance in ejector mode are specifically investigated, including rocket ejector parameters, geometric configurations of RBCC engine, secondary fuel injection schemes, flight Mach number and altitude. Thirdly, the research progress on key techniques of the RBCC ejector mode in recent two decades is reviewed from four aspects, namely the combustion organization, the mixing enhancement, the resistance to backpressure and the ejector/ramjet mode transition. Finally, some suggestions for the future work on the RBCC ejector mode are proposed.