Study on the Influence of Different Methane Injection Strategies on the Combustion Characteristics of RBCC Engines

This study investigates methane injection strategies for an RBCC combustor under Mach 6 flight conditions. Combining ground experiments and numerical simulations, single-stage and dual-stage injection approaches under a constant global equivalence ratio and fixed geometric throat height are compared. Compared with single-stage injection, dual-stage injection significantly enhances the fuel–air mixing and combustion efficiency, leading to increased chamber pressure and improved overall combustion performance. Among the dual-stage injections, reducing the equivalence ratio of the central strut while increasing that of the fuel struts shifts the main combustion zone downstream. This redistribution promotes more complete mixing and combustion in the downstream region, intensifies the precombustion shock train, and improves the overall flow stability. By maintaining the global equivalence ratio while adjusting the local fuel distribution between injection locations, it is possible to actively control the combustion heat release profile, thereby enhancing the performance of RBCC engines under high-Mach conditions.