Holographic Interferometric Observation of Shock Waves Discharged from an Open-End of a Square Cross-Sectional Shock Tube.

Abstract

This paper describes results of holographic interferometric observation of the evolution of shock waves and the primary vortex loop discharged from the open-end of a 40 mm × 40 mm square tube. Experiments were conducted by using the square tube connected to a 60 mm × 1500 mm diaphragmless shock tube. Holographic interferometric flow visualization viewed from the axial direction was carried out using a diffusively-reflected beam as the object beam. In order to interpret the observed three-dimensional shock-wave motion, numerical simulations were also carried out by solving the Euler equations with the dispersion-controlled scheme. The experimental interferogram was compared with numerical visualization results. The three-dimensional transition of the shock wave configuration from a planar to a spherical shape and the development of the primary vortex loop from a square shaped to the three-dimensional structure were clearly observed.