Surface Flow Characteristics of Double-Fin Shock-Wave/Boundary-Layer Interactions*

Shock-Wave/Boundary-Layer Interaction (SBLI) is ubiquitous for supersonic and hypersonic air vehicles, and can often lead to undesirable effects on internal and/or external aerodynamics. Even in simple geometries, SBLI flow fields are complex where the fundamental flow physics remains the subject of studies so that the adverse effects can be minimized or controlled for practical applications. In the present study, a crossing-shock SBLI generated by using a Double-Fin is experimentally investigated at Mach 2 and 3 as a canonical building block SBLI. Corresponding Single-Fin generated SBLI are also examined for comparison with the Double-Fin flowfield. Surface flow visualization is utilized to clearly document pertinent surface features such as the separation line, upstream influence and shock crossing. In order to capture the global surface pressure field beneath the interaction, conventional and fast response Pressure Sensitive Paint (PSP) are used to obtain mean and unsteady pressure maps. Spectral Proper Orthogonal Decomposition of the unsteady PSP fields reveals the existence of traveling pressure waves on the surface, originating from upstream influence. The behavior of these waves and other interesting interaction dynamics revealed through these experiments are discussed.