CFD analysis of shock tube for blast impact testing

Abstract

Shock tube is an experimental apparatus used to impart shock loading for testing various materials and designs. Shock loading induced by the shock tube is a safer alternative to conventional blast impact testing. Blast testing is critical for material selection, particularly in critical military structures exposed to blasts or shock waves. A compressed gas driven shock tube with a diaphragm separating the driver and driven section is used in the present study. Diaphragms of three different thicknesses (2 mm, 3 mm and 4 mm) are selected for the analysis. The maximum threshold pressure in the driver section increased with an increase in diaphragm thickness. Analytical equations are used to calculate the peak reflected pressure and energy which is incident at the end of the driven section. Computational fluid dynamics (CFD) simulation is performed on commercial software ANSYS Fluent 19.0. The reflected pressure–time graphs were compared with experimental tests to validate the CFD results. The CFD simulation was used to visualize various stages of the shock tube experiment by studying the pressure contours of the shock wave. The CFD results provided the parameters required for the calculation of the incident energy. The maximum incident energy available at the end of the driven section using diaphragm thickness 4 mm was 46.72 KJ. This value was 1.73 and 4.67 times that of the maximum incident energy obtained using diaphragm of thickness 3 mm and 2 mm respectively.