An investigation on multistage rockets ejection in RBCC engine

Three-dimensional two-phase numerical method is used to investigate the combustion processes in RBCC ejector mode. A new structure of primary rockets arrangement (namely multistage rockets ejection) is proposed, i.e. one primary rocket in combustion chamber is embedded in the rearward-facing step at the 50% distance of upper longitudinal wall in combustion chamber, and the other primary rocket, embedded in the center strut. The investigation shows that multistage rockets ejection improve performance of RBCC compared to ordinary rockets structure. At the state of 1st stage rocket working at equivalent ratio and the 2nd stage rocket at fuel-rich state. The results show that the 1st stage rocket not only ejects air from far-field, but also suppresses the chamber pressure affecting the inlet. The 2nd stage rocket ejects the flow in chamber continuously, and works as the flame holder simultaneity. The mechanism of multistage rockets ejection is the optimized combination of DAB and SMC. It may be the better choice under current research of the RBCC engine in ejector mode for secondary combustion.