An Experimental Study of Reflected Shock Wave Structure over a Wedge with Surface Roughness. 2nd Report. On the Local Structure.

Abstract

Detailed experimental analysis was made on the shock reflection over a wedge with surface roughness in a shock tube. The roughness was made by gutters carved on the wedge. The incident shock Mach number was Ms=1.43. The experimental parameters were the wedge angle and size of gutters. The wave configuration in the neighborhood of the triple point on the wedge is found to be nearly similar between model wedges. Detailed insight into the triple point trajectory shows that it is not a straight line but a slowly varying curve with a kink point where the slope of the tangent to the curve increases discontinuously and that the kink point coincides with the location where the secondly developed shock wave from the gutters overtakes the triple point. The local trajectory angle was found to decrease monotonously from the leading edge to the kink point, where it increases discontinuously. It then begins to decrease again, but not as steeply as the first decreasing region. The effective incident and reflective angles differ much from the ones obtained from the three-shock theory in front of the kink point. The angles coincide fairly well after this point. It is concluded that the secondary shock wave developed from gutters plays an important role for the structue of the reflected waves in the region investigated.