Experimental Investigation of Interactions Between Blunt Fin Shock Waves and Adjacent Boundary Layers at Mach Numbers 3 and 5

摘要

Strong interactions between fin generated shock waves and laminar and turbulent boundary layers are investigated using cylindrically blunt, slab type fins mounted at various streamwise stations on a sharp leading edge flat plate. Surface pressure distributions, total pressure rake surveys, and schlieren oil film and sublimation photographs are obtained for Mach 3 and Mach 5 flows. Reynolds numbers, based on free stream conditions and the length of the plate ahead of the fin leading edge, vary from 0.1 to 4.8 million. The separated flows resulting from the interaction are highly vortical in nature. Nevertheless, in the plane of symmetry, the separated flows ahead of the fin bow shocks resemble two-dimensional separated flows; the laminar plateau and turbulent peak pressures can be estimated using expressions developed for two-dimensional separated flows. The extent of laminar separation ahead of the fin increases with increasing Reynolds number; turbulent separation is insensitive to Reynolds number and occurs approximately two diameters upstream of the fin leading edge. The separated flows and interaction regions scale with fin diameter for diameters greater than or approximately equal to the local boundary layer thickness. (Author)