An Experimental Study of Shock Wave Boundary Layer Interactions Over Curved Surfaces of Supersonic Turbine Cascades

This study investigates shock wave–boundary layer interactions (SBLI) on both convex and concave surfaces of supersonic turbine blades using high-speed (50,000 Hz) shadowgraph imaging technique. The unsteadiness of separation bubbles and the resulting shock structures are examined and compared with both flat plate models and large eddy simulations. The results highlight the significant influence of surface curvature on SBLI behavior. On the convex surface, the impinging shock generates a large separated SBLI region, whereas a much smaller interaction forms on the concave surface. A bistable behavior is observed on the convex side, where the boundary layer alternates between an attached and a detached state. To isolate the role of curvature, a single-blade configuration was also tested, confirming that the impinging shock induces separation. In this configuration, the separation shock exhibited low-frequency bi-stability, intermittently jumping between two distinct locations.