Experimental and Numerical Investigation of Shock Wave Focusing and Reflection

The incident shock wave focusing and reflection on the two parabolic reflectors were studied by means of high speed photograph technique and numerical simulation method. The experimental shadow photographs and computational density contours were obtained, and the good agreements between the experimental and computational results were presented. The properties of the gasdynamic focus, formed by shock wave focusing, were analyzed. The results show that for both reflectors studied the gasdynamic focus is formed by the collision of two triple points at the axis, and that this focus is located in the vicinity of the corresponding geometrical focus. The shock-shock structures after shock wave focusing are different for the two reflectors. For the shallow reflector, the bow shock waves form on the surface of reflector before the reflection of incident shock wave; it takes long time to complete the focusing once incident shock wave reflects from reflector; the bow shock waves do not intersect each other during the shock wave focusing and reflection. For the deep reflector, it takes short time to complete the focusing, the bow shock waves have intersected during the shock wave focusing and reflector, and this process leads to the more complex shock-shock structure.