Surface Properties of Double-Fin Generated Shock-Wave/Boundary-Layer Interactions

Abstract

Shock-Wave/Boundary-Layer Interaction (SBLI) is ubiquitous for high-speed air vehicles. In the present study, the surface flowfield properties for SBLI due to symmetric Double-Fins at fin angles of 8 degree and 10 degree and a freestream Mach number of 2 are experimentally investigated; a Single-Fin with 10 degree fin angle case is also explored as a comparison case. Oil surface flow visualization is used to capture distinct flowfield structures such as separation and upstream influence. Pressure sensitive paint (PSP) is used to obtain global surface pressure fields. In-situ refinement of the PSP calibaration using Kulite unsteady pressure sensors allows one to obtain the unsteady pressure distribution in areas that were traditionally inaccessible with traditional sensors with a high degree of confidence. The details of the characteristics of Double-Fin SBLI surface topology distinct from Single-Fin SBLI are discussed for the 10 degree fin angle by using oil flow visualization and PSP techniques. Furthermore, the effect of the fin angle on Double-Fin SBLI is characterized. Steady surface pressures acquired by using a 32-port scanner along the centerline of the shock crossing are compared with previous experimental data wherein fin-tip-spacing is found to be an appropriate parameter for normalization. It is revealed that normal Mach number of the oblique shocks generated by the fins is a useful parameter to determine the interaction strength of Double-Fin SBLI.