Experimental Investigation Of Three Dimensional Shock Wave Turbulent Boundary Layer Interaction An Exploratory Study Of Blunt Fin Induced Flows PDF Download

An experimental study has been made of blunt fin-induced shock wave turbulent boundary layer interactions. This type of interaction is known to be highly unsteady. The objective of this experiment was to determine the characteristics of the fluctuating surface pressure distribution and the parameters controlling it. Tests have been made using fins of different diameter, D, with incoming turbulent boundary layers varying in thickness, Delta, in the ratio of about 5:1. Measurements have been made on the fin centerline and up to four diameters outboard of it. All tests were made at a Mach number of 2.95 and a unit Reynolds number of 6.3 billion/m, and under approximately adiabatic wall conditions. The measurements show that very high intensity r.m.s. pressure levels occur--up to almost two orders of magnitude above that of the incoming boundary layer. The highest intensities occur on centerline ahead of the fin. Here, the r.m.s. pressure distribution is characterized by three distinct peaks which decrease at different rates with distance outboard. Even four diameters off centerline, the maximum r.m.s. value in the distribution is still an order of magnitude larger than that of the incoming boundary layer. Outboard of the centerline, the r.m.s. pressure level downstream of the freestream shock wave steadily decreases. Within a distance of six to eight diameters it is close to the undisturbed value. With different diameter fins and different boundary layers, the qualitative characteristics are the same. The quantitative results depend on the ratio D/Delta. (Author).