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Animated display of sequential holographic interferograms of shock-wave/vortex interaction in a confined space

Paper demonstrates dynamic observation of the interaction of a shock wave with a vortex in a confined space by an animated display of sequential holographic interferograms. In conventional flow visualization methods, high speed photogrametry is a useful tool to observe high speed flows but its spatial resolution is somewhat limited. Holographic interferometry, on the contrary, can produce image information with a very high spatial resolution but only provides those at a specified time instant. In order to secure a dynamic display of shock wave phenomena, sequential interferograms must be taken successively at a given delay time in a shock tube which has a higher degree of repeatability. Experiments were conducted in a 60 mm X 150 mm shock tube at shock Mach number of 1.2 in air. Double exposure holographic interferograms were taken at every 5 microsecond time delay and a series of more than 30 interferograms was sequentially re-arranged on a computer so as to animate the interferograms. The animated result was then compared with a numerical simulation using a finite difference method with shock adaptive unstructured grids.