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

在高速工程应用中，激波边界层干扰（SWBLI）是边界层与超声速外流场之间的一种密切耦合现象。SWBLI的显著特征之一是非定常激波阵面围绕平均位置振荡。激波振荡可以导致表面压力波动水平升高，当足够强时，可能导致灾难性的故障，例如在超音速飞行器中的结构损坏。尽管非定常激波在高速空气动力学中具有关键的性质，但在我们对控制激波振荡的机制的理解中存在关键的差距，这是本建议的动机。在这里，我们进行实验，采用国家的最先进的基于图像的技术，如高速纹影可视化和粒子图像测速，检查不稳定的SWBLI动力学。特别是，冲击强度如何影响的振幅和频率的内容的不稳定性将进行详细的调查，以改善目前的模型，不考虑冲击强度的影响，使他们能够更好地预测实验观察。

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.