Geometrical Perception of Convex Surface Reflections

Abstract

Experiments and inviscid numerical computations were performed in air at an incident shock wave Mach number of 1.3. The incident shock waves were reflected over cylindrical convex surfaces. The models differed in the radii and initial angles. Great agreement was obtained between the high-resolution computations and the high-resolution experiments. Examination of the flow Mach number distributions revealed a fundamental difference between pseudo-steady and unsteady reflections. As the radius of the surface increases, the orientation of the reflected shock wave, with respect to the incident shock wave, approaches its orientation in a pseudo-steady reflection. This means that the radius of curvature does play a rule in the RR reflection. Therefore, it is reasonable to assume that the RR→MR transition is also affected by the radius of curvature. This observation is in contrast with the claim that variation between the RR→MR unsteady and pseudo-steady transitions is a result of optical limitations as was previously suggested by several studies. The problematic estimation of the RR→MR transition is also discussed. This study is a section of an extensive ongoing research dealing with the unsteady mechanism that leads to transition.