Experimental Study of Hypersonic Fluid Structure Interaction with Shock Impingement on a Cantilevered Plate

This work investigates fundamental fluid-structure interaction (FSI) experiments performed in a short duration hypersonic wind tunnel at Mach 6. The thesis aims to discuss and quantify the relationship between structural deformations and viscous aspects such as transition, separated flow and shock wave – boundary layer interactions (SWBLI). Part of the findings will be used to describe the impact of deployment and deformation on the performance of control surfaces. The main experiment involves a shock impinging on cantilevered elastic plate. The pressure increase, determined by the shock reflection on the plate, causes the cantilevered plate to oscillate. The plate motion affects the salient feature of the SWBLI in terms of length of the separated region, transition, peak heating and peak pressure. The problem is broken down into its main features and driving phenomena. In fact, preliminary experiments involve a cantilevered plate without impinging shock and a shock impinging on a rigid plate, in order to separate the phenomena purely due to FSI or SWBLI. Measurements consist of time-resolved sparse pressure and temperature measurements as well as surface measurements. Pressure-sensitive paint (PSP) and IR thermography are used to investigate and quantify the impact of three-dimensional effects on pressure and thermal distributions. In this work, three-dimensional effects are the result of limited plate width and/or Görtler boundary layer instability. The experimental data is compared against transient fully laminar and fully turbulent numerical solutions. Among the major findings, the thesis demonstrates that the boundary layer displacement thickness cannot always be considered a point function of the local plate inclination and speed. The numerical solutions significantly underestimate peak heating and peak pressure when boundary layer transition takes place within the separated region. Gortler boundary layer instability triggers the transition resulting in peak hating fluctuations close to 10%. Concerning control surfaces, transition in the separated region can lead to levels of heating 100% higher than the laminar values. Finally, a 1 % control surf~ce deformation at the trailing edge due to fluid-structure interaction results in a 2 - 3% loss in efficiency