Effect of Swept Shockwave Boundary-Layer Interaction Strength on Surface Skin Friction

This investigation examines the flowfield topology beneath the single fin-generated shockwave boundary-layer interaction as a function of shock interaction strength and incoming boundary-layer thickness. A systematic application of oil film interferometry produced an experimental reconstruction of global skin friction maps for various Mach number and fin angle combinations. To determine the effect of boundary-layer thickness, data from the current study were compared against existing experimental data sets with thinner incoming boundary layers. Results for identically matching flow/geometric conditions show a good agreement between trends seen across the conical region of the interaction and exhibit skin friction coefficient peaks in the same position. Cases corresponding to a relatively thicker boundary layer showed higher skin friction coefficient values along the interaction periphery and upstream regions. An angular scaling was applied to align the inviscid shocks of data sets that matched interaction strength, and the results show similar behavior. The peak skin friction coefficient shows a monotonic increase with increasing shock strength. Conversely, the upstream normalized peak skin friction coefficient depends on boundary-layer thickness and shock strength. These findings indicate that boundary-layer effects are limited to the interaction periphery, whereas viscous effects driven by shockwave–boundary-layer interactions dominate the interior region.