Performance improved by 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 method namely multistage rockets ejection is proposed, that is to put one primary rocket in combustion chamber embedded in the rearward-facing step located at the 50% distance of upper longitudinal wall in combustion chamber, and left the other primary rocket embedded in the center strut. The performance of RBCC investigated shows that multistage rockets ejection has improved performance compared to ordinary rockets structure. At the state of 1^st stage rocket working at equivalent ratio and the 2^nd stage rocket of fuel-rich, the thrust of the whole engine could be increased associated with ejection mass flow rate also increased. The results with deeply analysis show that the 1^st stage rocket not only ejects air coming from far-field, but also suppresses the chamber pressure affecting the inlet. The 2^nd 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.