Shock-wave/Boundary-Layer Interactions (SBLI): Physics and Control

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Shock-wave/boundary-layer interaction (SBLI) is a critical area of research for the development of all future aerospace systems as they are ubiquitous in high-speed aerodynamic flows. The extraordinary pressure and thermal loads in the regions of SBLI poses a wide variety of problems including damage/rapid fatigue to aero-structures and associated protection systems, inlet flow distortion and engine unstart, all of which could have adverse consequences. Previous studies have noted that the low frequency unsteadiness of the shock-wave/separation region as a dominant phenomenon and indicated that even the behaviour of mean properties cannot be fully understood without some knowledge on the unsteadiness. Moreover, computational studies find it difficult to accurately capture the dynamics of SBLIs due to the limitations of the models employed. Therefore, it is vitally important to perform experimental investigations of shock-wave/boundary-layer interaction using state-of-the-art experimental techniques. The aim of this project is to develop a supersonic facility where state-of-the-art experimental methods can be employed to obtain qualitative and quantitative information. Advanced optical diagnostic techniques including Particle Image Accelerometry (PIA) and multiple-plane Particle Image Velocimetry (PIV) will be developed. High-quality imaging measurements will be performed together with fast-response surface pressure measurements to characterise the unsteadiness and the three-dimensional nature of shock-wave/boundary-layer interactions in a variety of flow configurations. Measurements will be obtained in the upstream supersonic boundary layer, the interaction region and in the shock induced separation region. The data will be carefully analysed with the aim of developing a physical framework to explain the causes responsible for the unsteadiness and the three-dimensional nature of the flow field.Generic (vortex generators, streamwise slots) and state-of-the-art (piezo actuators) control schemes will be employed to control the frequency and amplitude of shock-wave unsteadiness. The components will be actuated and phase-averaged velocity, acceleration and pressure fields will be obtained. The data will be used to understand the response of the flow to the control scheme, which in turn can help in development of improved control strategies. The feasibility of employing closed-loop schemes to achieve necessary localised control will also be explored.