Control of shock-wave/boundary-layer interaction using a backward-facing step

Flow separation induced by the shock-wave/boundary-layer interaction is detrimental to the performance of a hypersonic inlet. This paper develops a new method to control the shock-wave/boundary-layer interaction using a backward-facing step. The backward-facing step is placed on the shock-wave generator with a deflection angle of 14 deg. The shock-wave generator and a flat plate construct a simple hypersonic inlet. The control ability and mechanism are numerically studied using Reynolds Averaged Navier–Stokes equations at a freestream Mach number of 5. The results suggest that the backward-facing step can effectively suppress the flow separation. The reason is that the backward-facing step replaces the strong shock-wave in the baseline inlet with two weak ones. Consequently, the separation bubble in the controlled inlet is much smaller than that in the baseline inlet. Moreover, a parameter study is performed to analyze the effect of the design parameters of the backward-facing step on the control ability. The wave systems in the controlled inlet are classified into three types based on the results. However, only the effective wave system can suppress the shock-wave/boundary-layer interaction.