Investigation of unsteady regular and Mach reflection in water using an image converter camera

The oblique collisions of two shock waves in water are investigated by an image converter camera. These two shock waves are produced by the detonation of two plane efficient explosives at angles to each other. The propagating shock wave is confirmed to be pseudo-stationary by framing photographs taken with by the image converter camera. Configurations of the shock wave are also obtained by the usual shadow graph technique using a laser beam as a source of light. The velocity of the head wave is calculated by use of the shadow graph. Using the Rankine-Hugoniot relation between the front and rear of the head wave, we can calculate the pressure across the underwater shock wave. The streak photographs of the intersection of two plane shock waves are also obtained by the image converter camera. When two shock waves collide, Mach reflection occurs at an early stage, and transits to regular reflection. The transition from Mach to regular reflection is fully nonstationary and therefore there is great discrepancy between these results and Neumann's two shock theory. We confirmed that this image converter camera is capable of investigating the nonstationary transition process between Mach and regular reflection in water.