The Experimental Study of the Effect of a Diaphragm Thickness on the Position of Planar Shock Wave Formation in a Gas Shock Tube

Shock tube is an equipment in which by creating a pressure difference between driver and driven section via the bursting membrane has the ability to generate shock wave with very short rise time. One of the important parameters in the shock tube is the planar shock wave and the distance of its formation along the driven section. In this study, the shock wave pressure has measured at different sections along the shock tube as well as at different radial distances, using three piezoresistive pressure sensors. Experiments were repeated with three different thickness of diaphragms 0.1, 0.2 and 0.3 mm. Diaphragms were made of Mylar. The results of the experiments were extracted using TRAww software, which is a software for signal processing of the pressure sensors; and the distance of the planar shock wave for different diaphragms was obtained. The results show that by increasing the diaphragm thickness and thus increasing the explosion pressure (pressure of the driver area), the shock wave pressure increased and the planar shock wave propagates further away in the driven section. The uniform duration of the shock wave using a diaphragm with a thickness of 0.1 mm is smaller than the other two diaphragms, and the planar shock wave is not stable until the end of the shock tube. Also, the pressure drop in driven section after rupture of the diaphragm increases with increasing diaphragm thickness.