<title>Interferometric CT technique for three-dimensional shock wave phenomena</title>

Abstract

An interferometric CT technique is developed to observe three- dimensional phenomena in shock tube experiments, and is applied to investigate three-dimensional features of shock waves and vortices discharged from a square open end. A small duct model is introduced in the test section of the shock tube, and is rotated around its central axis to change the observation angle in order to obtain the finite-fringe interferograms from multi-directions. The CT images of the density distribution are obtained with good quality by carefully selecting the projection data within the limited ranges of the incident shock Mach number M<SUB>i</SUB> and the frontal shock position. The rotation angle is changed from 0 degree to 90 degrees in an interval of 5 degrees. For M<SUB>i</SUB> equals 1.50, the three-dimensional nature of the distortion of vortices and the shape of secondary shock wave are clearly illustrated by pseudo-color images of the density distribution and isopycnic surfaces. The CFD images exhibit a good agreement with the CT images.