Effects of Shock-Induced Separation on Boundary Layer Transitional Mechanisms

The transitional mechanisms of a natural boundary layer as well as one interacting with shock-waves are investigated at supersonic speeds. Experiments are performed over a flat plate and a 6 degrees compression ramp at a Mach number of 1.65, using Pitot probes and hot-wire anemometry. Comparisons are drawn between the two configurations focusing on the evolution of unstable modes of the boundary layer. Measurements are made inside the laminar boundary layer to study the primary and secondary instabilities of the natural transition process. While the flat plate exhibits the classical mechanisms of transition for a zero pressure gradient boundary layer, the compression ramp shows an altered transition process where the secondary instabilities play a less important role.