Effects of Surface Curvature on Flow Interactions of Small Cylindrical Protuberances and the Supersonic Turbulent Boundary Layer

This a combined experimental and computational study to evaluate the aerodynamic forces resulting from the interaction of small cylindrical protuberances and the boundary layer of a cylindrical body in Mach 3.0 flow. It is a continuation of a study on the effects of the same protuberances on the flow over a flat plate model. Cylindrical pin protuberances with diameters of 2 mm and 6 mm were tested. Protuberance heights of 2 mm, 4 mm and 6 mm were tested on a 63.5 mm diameter cylinder with an ogive nosecone. The boundary layer thickness was approximately 2.6mm. The set 2 mm diameter protuberances were also tested in a group of four at all three heights. Oil flow visualization, schlieren photography, and pressure data were recorded with a variety of pin configurations to capture a three dimensional understanding of the flow structures. Both schlieren and pressure data were captured a 10 kHz to capture the unsteady flow behavior. The results were that the there was a decrease of between 5 and 9% in the side forces produced by the pins. The drag was increased in some cases but reduced by up to 31% for the largest pins. Flow visualization showed that the upstream separation point did not move due to the curvature but the lateral spread of the separation front was limited and the peak pressures decreased due to flow relief from the addition on curvature.