Abstract: The internal flow fields of supersonic combustion ramjet （scramjet） combustion chamber with strut or normal wall injectors are simulated numerically by using the Favre-averaged Navier-Stokes equations with the Baldwin-Lomax algebraic turbulence model. During the simulations, the second order H. C. Yee's TVD scheme is used for the inviscid flux terms and a central difference is used for the diffusion terms. In computing the flow fields in the combustor, the effects of the fuel-injection scheme on the fuel/air mixing process and the combustion performance of the scramjet combustor are studied comparatively. For strut fuel injection upstream of the backward facing step, a pair of large-scale axial vortices induced by struts has a strong opposite effect on the fuel distribution in the combustor and prevents the fuel/air mixing process, while the normal-wall fuel injection will bring the small-scale axial vortices within the fuel fields behind the injectors, which is the key to enhance the mixing efficiency and combustion efficiency of the scramjet combustor.

Key words: ramjet, supersonic combustion, numerical simulation, strut, backward facing step