Numerical investigations of laminar-turbulent transition control in compressible streamwise corner flows

本文的基础研究是基于线性稳定性理论和直接数值模拟的可压缩层流转角流主动流动控制的首次研究。当两个平板以直角相交，形成平行于自由流动方向的角形或楔形时，就得到了基本构型。这里将研究和比较控制角部流动中层流-湍流转变的不同有效方法：全局方法和局部方法，以及壁面吸力与加热和冷却的方法。这些研究旨在提高顺流角区流动的临界雷诺数。参考我们在风洞实验中观察到的基流变形导致流动失稳的最新结果，以及在直接数值模拟中观察到空间瞬变扰动增长的情况，本文旨在研究是否可以通过角区的局部吸力来稳定这两个过程。这些研究的目的是使变形的边界层稳定到未变形的临界雷诺数及以上，如果可能的话。

The present fundamental research aims at a first-time investigation of active flow control in compressible, laminar streamwise corner flows based on linear stability theory and direct numerical simulations. The basic configuration is obtained when two flat plates meet at a right angle to form a corner or a wedge parallel to the free-stream flow direction. Different active means to control laminar-turbulent transition in the corner flow are to be investigated and compared here: Global versus local methods, as well as suction versus heating and cooling at the walls. These investigations aim at increasing the critical Reynolds number of the streamwise corner flow.In reference to the latest findings in our previous work, where the base-flow deformation observed in wind-tunnel experiments led to a destabilization of the flow, and where spatial transient disturbance growth was observed in direct numerical simulations, it is intended to investigate whether both processes can be stabilized by local suction in the corner region. These investigations aim at stabilization of the deformed boundary layer up to the critical Reynolds number of the undeformed and beyond, if possible.