Numerical simulation about mixing characteristics of an inlet-fueled scramjet engine

Abstract

In the present study, the mixing characteristics of an inlet-fueled scramjet engine have been numerically investigated. For this purpose, a generic two-dimensional four-shock inlet configuration, which was designed to fly at an altitude of 22 km with a flight Mach number of six, was adopted. Under-expanded ethylene fuels were injected from three orifice injectors at the end of the first ramp, and the effects of injector array spacing, fuel injection angle, equivalent ratio, molecular weight of fuel, and inlet ramp angle on the mixing efficiency were assessed. Steady-state flow calculations were performed by using a three-dimensional Navier-Stokes flow solver, including a non-equilibrium model, on unstructured meshes. For the closure of turbulence, the ω-to SST turbulence model was employed. It was observed that the overall fuel-air mixing efficiency increases as the injector spacing, inlet ramp angle, and equivalence ratio increase. It was also observed that the effect of fuel molecular weight on the mixing efficiency is similar to that of equivalence ratio. The total net increase in the internal inlet drag due to the inlet injection was 2.5%.