Fin-Induced Shock Boundary Layer Interaction on Mach 5 cylinder.*

Fin-induced Shock Boundary Layer Interactions (SBLIs) have been investigated on a hollow cylinder in the Mach 5 Ludwieg tube (LT5) at the University of Arizona. The study has been conducted in support of a DLR flight test as part of the STORT program and complements parallel experiments of similar SBLIs on planar surfaces. A half-scale model of the fin-base diameter flight geometry has been incorporated into the hollow cylinder model with variable total length between 400 and 1000 mm, such that the boundary layer state can be controlled between laminar/transitional/turbulent. Effects of surface curvature and the finite fin geometry have been assessed using high-speed schlieren, surface pressure transducers, and IR thermography. The inferred flow topology indicates separation is present around the base of the fin, and show the SBLI remains largely in Zone 1 (also referred to as the viscous inception region) due to the relatively large boundary layer that the fin experiences. Expansion waves from the fin further influence the nature of radial SBLI development. Results are contrasted to flat plate experiments of a similarly proportioned fin geometry and provide vital insights into understanding future data to be gathered from the flight experiment.