On the Interaction of 3D Protuberances with a Supersonic Turbulent Boundary Layer

Abstract

A comprehensive Computational Fluid Dynamics study of the surface pressure fluctuations induced by a cylindrical protuberance in a supersonic turbulent boundary layer is presented. The effects of two important parameters on the surface pressure fluctuations are investigated; protuberance height to boundary layer thickness and surface curvature. The turbulent boundary layer is modeled using a hybrid Reynolds Averaged Navier-Stokes and Large Eddy Simulation approach known as Detached Eddy Simulation (DES). At first, extensive comparisons to experimental data for surface pressure coefficient and the unsteady surface pressure coefficient were performed. Results from our CFD computations compared well to the experimental data in the wake region downstream of the protuberance and in the vicinity of the protuberance at other upstream and to the sides of the protuberance. Increasing the protuberance height relative to the boundary layer thickness resulted in higher sound pressure levels on the surface. In addition, the surface pressure fluctuation showed more coherence in the spanwise direction ahead of the protuberance and immediately downstream of it. Increasing the surface curvature lowered the sound pressure levels on the surface and resulted in stretched coherent structures in the spanwise direction. Adding a fairing to the protuberance resulted in lowering the sound pressure levels on the surface. As expected, the radiated sound was more intense in the downstream direction and to the sides of the protuberance.