Effect of Shock Impingement location on the Fluid-Structure Interaction over a Compliant Panel

Abstract

This work discusses results from an on-going effort towards the experimental investigation of the fluidstructure interaction on a compliant panel subject to shock wave boundary layer interaction in a supersonic flow. Experiments were carried out to understand the mean flow characteristics associated with the fluidstructure interaction on a compliant panel subject to a 2D impinging shock generated by a 10̊shock generator for a Mach 2 flow with Re=4.35x107 /m, using qualitative and quantitative flow diagnostics, namely shadowgraph to understand the shock structures involved, surface oil flow to understand the two and three dimensionality of the interaction, separation bubble characteristics and binary FIB to explain the mean pressure field over the compliant panel under the various test conditions. Four shock impingement locations: panel leading edge, quarter panel length, panel center and three quarters of the panel length were tested. For each shock impingement location, three cavity pressures corresponding to cavity at ambient, freestream static pressure and 1.2 psi were tested. The compliant panel results were compared with the rigid plate, which served as a baseline model, to understand the differences between the interactions on the rigid and the compliant panel. Several interesting features were observed: 1) The interaction on the panel across cavity pressures was observed to be curved along the centerline compared to the nominally 2D straight line interaction observed over 70% span of the rigid plate. 2) For the leading edge and quarter impingement locations, the compliant panel was subject to two interactions, a primary interaction from the shock generated from the tip of the shock generator which spanned over the entire model, and a weaker secondary interaction from the base of the shock generator which was observed to be highly three-dimensional and was bounded within the extent of the panel , increasing the complexity of these two shock impingement cases compared to the case where the panel was subject to only a single primary interaction. For the central and three-quarter shock impingement locations, the panel was subject to only a primary interaction. 3) The primary interaction for the leading edge and quarter impingement locations extended across the entire span of the model. However, the secondary interaction was observed to be highly three-dimensional in nature. An increase in the centerline mean pressure compared to the baseline case was observed for panel interaction for all cavity pressures. This is indicative of the effect of the panel compliance and cavity pressure in defining the subsequent fate of the interaction.