A study on shock-wave/boundary-layer interaction with varying flow deflection angle

Abstract

Shockwave boundary layer interaction is studied for oblique shocks generated from a shock generator with a varying flow deflection angle. A two-dimensional shock generator with a wedge-shaped geometry is fixed inside the test section and mounted to the wind tunnel's top wall. The shock generator is made to pitch up and down so that the net flow deflection angle changes because of the pitch motion. As a result, the shock strength changes for a varying flow deflection angle of the shock generator with a fixed incoming Mach number of the flow. The imposed adverse pressure gradient on the boundary layer by this incident shock changes, which influences the shape and structure of the shockwave boundary layer interaction. Three different shockwave boundary layer interaction structures are observed with high-speed schlieren from the experiments conducted for the current study. Schematics for these structures' types are illustrated, and a model is presented to build the transition criteria for the flow deflection angles for which the transition would take place from one structure to the other. The two transition criteria, one for type 1 to type 2 transition and the other for type 2 to type 3 transition, are validated with the observed results from the experiments. Assumptions made for the transition criteria are also validated with experimental results.