Experimental analysis of unsteady shock formation from interactions with turbulent features in a flat plate turbulent boundary layer

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Shock wave–boundary layer interaction (SWBLI) where a close coupling exists between the boundary layer and the outer supersonic flow occur frequently in high-speed engineering applications. One of the striking features of SWBLI is an unsteady shock front that oscillates about the mean position. The shock oscillation can lead to an elevated surface pressure fluctuation level, which when strong enough may lead to a catastrophic failure, e.g. structural damage in a supersonic vehicle.Despite the critical nature of unsteady shock in high-speed aerodynamics, critical gaps exist in our understanding of the mechanism that governs the shock oscillation, which serves as a motivation for the present proposal. Here, we conduct experiments that employ the state-of-the-art image-based technique, such as high-speed schlieren visualisation and particle image velocimetry, to examine the unsteady SWBLI dynamics. In particular, a detailed investigation of how the shock strength influences the amplitude and the frequency contents of the unsteadiness will be conducted to improve current models, which do not take into consideration the effects of the shock strength, such that they are better able to predict the experimental observations.