Effects of primary rocket pressure on ejection and combustion in RBCC configuration for multiple modes

CFD method was used to examine effects of primary rocket pressure on the ejection and combustion in the whole flow field in a center-strut Rocket Based Combined Cycle (RBCC) engine at subsonic flight conditions. The simulations show that both the bypass ratio and engine performance increase with the primary rocket pressure as high as 26MPa and meanwhile no Fabri-choking appears in the mixing duct. The bypass ratio increased to be 22.4% and 40.0% at Ma=0 and Ma=0.8, respectively. The thrust not only produced by the primary rocket but also by the combustor and the aft vehicle body increase with increasing the primary rocket pressure and as a result the engine thrust impulse increased up to 11.5% and 25.3% at Ma=0 and Ma=0.8, respectively. Based on the detailed flow studies in the paper, it is concluded that primary rocket pressure plays an important role to improve engine performance at subsonic flights for a RBCC configured in multiple modes.