高超声速激波/边界层干扰流动失稳的机理研究

激波/边界层干扰是一种重要的基本流动现象，普遍存在于各类高超声速飞行器的流场中。深刻认识和准确预测激波/边界层干扰对高超声速飞行器的设计和研发具有重要的意义。本项研究聚焦二维或轴对称标准构型的高超声速激波/层流边界层干扰于再附区诱发三维流向条带结构这一流动失稳问题。该条带结构广泛存在于各类激波/层流边界层干扰流动中，可导致再附区局部热流增大甚至诱发边界层转捩，其产生机制尚存争议。本项研究提出以二维和轴对称标准构型作为研究对象，采用全局稳定性分析和输入-输出分析方法，从绝对和对流不稳定性两个方面，考察再附区三维流向条带结构的这一流动失稳现象。此外，本项研究将对以上两类不稳定性问题开展直接数值模拟，验证线性稳定性分析结果，揭示流动结构的非线性演化过程及其对再附区下游气动力/热特性和边界层流态的影响。

Shock-wave/boundary-layer interaction (SWBLI) is an important fundamental flow phenomenon that is frequently encountered during hypersonic flight. A deep understanding and accurate prediction of SWBLI is of vital importance to the development of hypersonic systems. The proposed project focuses on the formation of three-dimensional streamwise streaks that are extensively observed in hypersonic laminar interactions over many two-dimensional/axisymmetric canonical configurations. The streamwise streaks can significantly enhance the aerodynamic heating level and trigger laminar-turbulent transition downstream of flow reattachment. However, such phenomena are still poorly understood, and the underlying physical mechanisms remain unknown. In this project, global stability analysis and input-output analysis will be conducted to investigate the formation of streamwise streaks in terms of absolute and convective instabilities. Meanwhile, direct numerical simulations will be performed to validate the linear stability analysis results and to reveal the nonlinear evolution of the flow structure and its effects on the aerothermodynamic characteristics and boundary-layer state downstream of reattachment.