Digital processing of shadowgraph images taking into account the diffraction of light at a shock front

Abstract

The aim of the study is to determine the shock wave position in experimental shadowgraph images and to evaluate the accuracy by digital image processing. The experimental images were obtained with the shock tube with a rectangular channel. The shadowgraph optical system formed a parallel light beam. It passed through the plane-parallel quartz glasses of the shock tube test section. The process synchronization system at the facility allows registering the shadowgraph images of unsteady flows with shock waves with a high-speed camera or with a single frame camera. The obtained spatial intensity profiles were used to determine the coordinates of gas-dynamic discontinuities at different stages of the flow evolution. shadowgraph patterns were analysed taking into account diffraction at the shock front in case of a laser light source.