Leading Edge Bluntness Effects on Shock Wave/Boundary Layer Interactions Near a Convex Corner

Abstract

The cowl shock/ingested forebody boundary layer interaction is usually encountered near the hypersonic inlet shoulder, a convex corner, and sometimes causes the inlet to unstart. The bluntness of the forebody leading edge also affects the downstream convex corner flow, and that should be carefully considered to improve the inlet performance. A twodimensional inlet with a sharp leading edge and a series of blunt leading edges at Mach 5 were numerically studied. The relative positions of the cowl shock and the convex corner were changed to reveal the characteristics of the shock wave/boundary layer interactions with the corner expansion wave interference. Flow patterns and the distributions of surface pressure, heat flux, and friction coefficient involved were thoroughly studied. The results indicate that the boundary layer is even thicker and the flow is easier to separate when the bluntness of the leading edge increases. The variation trends of the separation extent with a sharp leading edge agree reasonably well with the estimations on the basis of inviscid analysis. However, the inviscid formulas established in the sharp leading edge case are not suitable for the blunt leading edge cases. With the aid of viscous simulations, it is found that the upstream effect of the corner extend a little farther and the dimensionless relative position range that can largely reduce the separation narrows with the increasing of the leading edge bluntness. To take into account the nonuniform flow in the boundary layer, a rapid calculation method of the incident shock (B. L.) was established. It is shown that the shock (B. L.) impinges on the corner can minimize the separation in the sharp leading edge case. However, the shock (B. L.) has to move downstream to minimize the separation when the leading edge is blunt.