Operation match between primary rocket and RBCC engine during rocket ejector mode

Based on the traditional “pressure equal plane” hypothesis, ejection performance analysis model for RBCC primary rocket was established. Operation match between primary rocket and RBCC engine was investigated. The results show that: If the area ratio of isolator cross section is less than 0.65, flow choke will appear in isolator under lower total pressure of primary rocket, limiting further improvement of air mass flow. For ground static condition, the air mass flow increases with the increase total pressure of primary rocket. If fabric choke appears, further increasing total pressure of primary rocket will cause descending of air mass flow. During rocket ejector mode, the operation of RBCC engine can be divided into 3 different states, inlet sub-critical state dominated by ejecting effect, inlet critical state dominated by ejecting effect, inlet super-critical state dominated by ram effect, while the critical Mach number for these states are 0.7 and 1.5 respectively.