Numerical and experimental investigation on the RBCC engine nozzle in ejector mode

The Rocket Based Combined Cycle (RBCC) engine, which integrates a high thrust to weight (T/W) rocket with a high specific impulse (Isp) airbreathing engine, shows its unique advantages as the potential propulsion candidate for the hypersonic vehicle. As the main component of thrust, the RBCC engine nozzle should be designed with a large expansion ratio when takes the wide flight envelope of the hypersonic vehicle into account. However, a serious over expansion occurs in the RBCC engine nozzle in ejector mode and results in the performance degradation. In this paper, numerical simulation and ground level static experiment are applied to investigate the operation characteristics of the RBCC engine nozzle in ejector mode. As a result, the flow separation appears in the subsonic status and the over expansion appears in the supersonic status inside the RBCC engine nozzle. Finally, an optimized nozzle configuration is designed, which improves its performance in ejector mode effectively.