Scaling of Incident Shock-Wave/Boundary-Layer Interaction at Expansion Corner

Shock-wave/boundary-layer interaction (SWBLI) involving expansion waves is a common and complex phenomenon in high-speed inlets, where accurate prediction of interaction length is crucial for detecting separation. Traditional scaling laws based on inviscid pressure ratios fail to capture expansion waves effects, causing significant errors in real flight conditions. This study undertakes both experimental and theoretical investigations into the interaction between an incident SWBLI and expansion waves. Using high-speed schlieren, planar laser scattering, and high-frequency pressure measurements, the impacts of shock impingement positions and expansion corner geometries on the interaction length were examined. The results indicate that expansion waves diminish the reattachment pressure rise and curtail the interaction length, particularly when the shock impinges closer to the corner and with smaller curvature radii. An improved scaling law was proposed, which involves replacing the inviscid pressure ratio with the measured peak pressure ratio and introducing an equivalent flow deflection angle. Additionally, a hybrid monitoring framework that combines this model with a machine-learning surrogate was developed. By using Kolmogorov–Arnold Networks and optimized sparse sensor configurations, it can accurately predict the peak pressure ratio and interaction length, presenting a practical solution for real-time SWBLI monitoring.