Numerical investigation of a Mach 9 oblique detonation engine with fuel pre-injection

In this study, the performances of a Mach 9 oblique detonation engine fueled by hydrogen are numerically investigated by solving the multi-species reactive Reynolds-averaged Navier-Stokes (RANS) equations with a detailed combustion mechanism. The fuel is perpendicularly pre-injected into the core airflow in the engine inlet by three parallel strut-injectors. It is demonstrated that mixing can be enhanced by the baroclinic effect of oblique shock waves, the incipient expansion of fuel jets and the intensive momentum exchange of vertical jets into the crossflow, resulting in a well-mixed fuel-air core flow before entering the combustor. Analyses of the two most dangerous zones that bear potential of pre-ignition suggest that no pre-combustion occurs in the inlet. Benefiting from the floor bleed structure, the upstream movement of the shock waves stops at the combustor's entrance and they remain stabilized in the combustor thereafter. Finally, the combustor is proved to work under the stable detonation mode of combustion, and the supersonic fuel-air mixture is fast burnt through the steady detonation waves generated in the combustor. The concept of the pre-injection oblique detonation engine has been numerically demonstrated, which provides a significant reference to further experimental studies and future engineering applications.