Corner effects on oblique shock wave boundary layer interactions in rectangular channels

Abstract

An experimental investigation of streamwise-corner separation effects on oblique SBLIs has been performed. Experiments were run in a rectangular cross-section blow-down type wind tunnel at Mach 2.5, with an impinging shock generated by an 8° wedge. Conical artificial corner separation bodies were designed to emulate the effects of corner separations on the oblique SBLI, and were moved up and downstream relative to the interaction to vary the corner effects. Oil flow visualisation was used to acquire the resulting separation topology. Surface pressure distributions were obtained using Pressure Sensitive Paint. The corner cones were placed in 19 different streamwise locations. This generated a wide variety of separation shapes, which became highly three-dimensional as the corner corner waves interfered with the interaction. It was shown that there is a quasi-2D relationship between separation length and pressure rise from separation to reattachment for any spanwise location, even for highly 3D separations. This was attributed to the spanwise shear stresses in the shear layer being significantly lower than in the wall-normal direction, meaning that spanwise momentum transfer is low. The separation length model provides a means for modelling the effects of corner waves on the primary separation. However, predicting where corner waves will intersect the separation region is complicated by the increased upstream influence behind the separation region.