Investigation of an Expansion Fan/Shock Wave Interaction Between Low Aspect Ratio Wedges

Abstract

Shock waves and expansion fans form in supersonic flows as a mechanism to allow fluid to flow conformally over a body. When bodies are in close proximity – such as in the aerospace applications of store carriage and release from aircraft, engine inlet design, and formation flying – these shock waves and expansion fans interact and give rise to an interesting flow field warranting further investigation. The present research focused on modelling an expansion fan/shock wave interaction both experimentally and numerically, and these results were used to validate the basic flow physics of the interaction as well as the analytical model to predict the shock curvature originally published by Li and Ben-Dor. From the results, it can be concluded that both the curvature of the shock and the deflection of the expansion fan increase with increasing shock generator angle of attack. The analytical solution for predicting the shock curvature derived by Li and Ben-Dor is valid for predicting the amount of curvature of the shock (i.e., the concavity of the shock, given by the second derivative of the equation for the shock curvature) but underpredicts the range over which the expansion fan/shock wave interaction occurs and is thus invalid for analyses concerned with the extent of the shock curvature and modelling the full interaction.