Quasi-Conical Free Interaction in Fin-Induced Shock Wave/Laminar Boundary-Layer Interactions

A numerical study was performed on the three-dimensional interaction between a laminar boundary layer and the shock wave induced by a sharp, unswept fin mounted perpendicularly on a flat plate at freestream Mach numbers of 2.64, 2.95, 3.44, and 3.93. The fin angles were 13, 16, and 19 deg. All the interactions were strong enough for the boundary layer to separate, and the separated flow features displayed a quasi-conical nature emanating from a virtual conical origin. The concept of quasi-conical fin-induced interactions, initially developed for turbulent interactions, was used to extend the free interaction theory to three-dimensional laminar interactions considered in the present study. The well-established scaling functions in free interaction theory were extended, and the results were found to agree reasonably with the theoretical trend. Surface-pressure distributions were plotted for the different cases studied and were found to have a plateau and dip that is typical of separated flows. The overlapping of the scaled pressure distributions reinforced the concept of quasi-conical free interactions for the range of Mach numbers and fin angles considered.