Comparison of sharp and blunt fin-induced shock wave/turbulent boundary-layer interaction
In this paper, results are presented from an experimental study of fin-induced shock wave/turbulent boundary-layer interaction. Semi-infinite fin models, with sharp and hemicylindrically blunted leading edges, were tested at Mach 3 in two high Reynolds number, adiabatic wall, turbulent boundary layers. Detailed streamwise surface pressure distributions were measured at several spanwise stations for angles of attack from 0 to 12 deg. The objective was to examine the spanwise development of the interaction region and determine its dependence on leading edge geometry and the incoming-flow parameters. The results show that for blunt fins there is a region of the interaction in the vicinity of the centerline where the scale and characteristics of the disturbed flowfield are controlled primarily by the leading edge diameter. Outboard of this inner, or "leading-edge dominated," region the interaction properties and spanwise development are essentially the same as if the leading edge were sharp. Thus there is an outer region of the blunt fin-induced flowfield in which the properties are effectively "independent of leading edge blunting." Nomenclature D = blunt fin leading-edge diameter h - fin height Lu = upstream influence measured relative to the freestream shock wave M = Mach number P = static pressure P2 = wall pressure downstream of interaction Re = Reynolds number X = coordinate in the plane of the test surface and aligned with the tunnel axis, with X= 0 at the fin leading edge Xs = coordinate in the X direction measured relative to the freestream shock wave Y = coordinate normal to the X axis in the plane of the test surface, with Y= 0 at the fin leading edge