Experimental Investigation of Hypersonic Sharp-Fin Shock-Wave/Transitional-Boundary-Layer Interactions

The shock-wave/boundary-layer interaction that is generated by a sharp fin at incidence on a flat plate is studied for the case of a transitional incoming boundary layer in a Mach-6 shock tunnel. Novel variations of several diagnostic techniques are employed to explore the mean and unsteady flow features induced near the surface of the plate. Fast-response temperature-sensitive paint (TSP) measurements are used to derive time-resolved heat-flux distributions in the interaction region. Plan-view high-speed schlieren visualizations are obtained through the surface of the plate through the use of flush-mounted windows; these visualizations provide a qualitative picture of the flow development and allow the behavior of high-frequency disturbances to be examined. Finally, multipoint wall-normal focused laser differential interferometry (FLDI) provides high-bandwidth, pointwise measurements of disturbance velocities, propagation angles, and turbulence intensities in the interaction region. Although the schlieren, TSP, and FLDI results show the flow to be transitional in nature, no strong evidence of modal content at any specific frequency is detected. Despite the transitional nature of the boundary layer, the mean heat-flux features determined by the TSP show good collapse when plotted about a virtual conical origin (as in the turbulent case); however, significant levels of unsteadiness are seen throughout the interaction and, in particular, in the inception region and close to the separation line.