Head-on collision of shock wave induced vortices with a cylinder and a sphere

Abstract

An experimental study has been conducted to examine the interaction of shock wave induced vortices with a cylinder and a sphere. The experiments were carried out using a 30 mm internal diameter shock-tube, using air as both the driver and driven gas. High-speed schlieren photography was employed to study the development of the flow-field and the resulting interactions with the body configurations. Wall pressure measurements were also carried out to study the flow quantitatively along the leading edge of the cylinder. Three different diaphragm pressures ratios of 3.95, 7.89, and 11.84 were examined; the experimental shock Mach numbers were 1.28, 1.51 and 1.63, respectively. The experimental results indicate that as the incident shock wave impinges on the frontal surface of the cylinder or sphere, it undergoes transition from regular to Mach reflection. The induced flow-field due to the interaction of the vortex ring with the two models is highly three-dimensional and time dependent. The vortex ring attempts to engulf the sphere, whereas, in the case of the cylinder, part of the ring accelerates rapidly in the lateral direction along the leading edge of the body, whereas, the remaining flow moves around the cylinder. In both cases, the ring maintains its structure throughout the interactions.