摘 要：在湍流流动中，雷诺应力是一个能够影响平均流动的重要动态量，它可以在很大程度上影响湍流中动能的传输，强烈的影响表面摩擦力，对于摩擦阻力和流动的分离起着至关重要的作用。因此，本文的实验目的是：针对后台阶流动，特别设计了能够沿着45°方向形成射流的直角形状的等离子体激励器对后台阶流动中的雷诺应力进行控制，同时实现对后台阶流动再附着位置的改变。实验过程中，按照台阶后流向位置0.5H（H为台阶高度）的自然不稳定性频率对直角形状等离子体激励器的激励频率进行调制。使用PIV(Particle Image Velocimetry)对台阶后0-2.5H的区域以及再附着区域进行测量。实验结果表明：在直角形状等离子体激励开启后，在台阶后0-2.5H的区域，围绕剪切层及其附近区域的雷诺应力各分量在最大数值上分别增加了42%(< >),75%(< >),46%(-< >),湍动能产生项在最大数值上减小了35%。在再附着区域，后台阶流动的再附着位置也向台阶的上游发生了移动。
Abstract: The Reynolds stress is the important dynamic quantity affecting the mean flow in the turbulent flow, it greatly affects the momentum transfer in turbulent flows, thus strongly influence skin friction, subsequently it plays a key role for friction drag and flow separation. So, The purpose of this article is to present the flow control with special designed right-angle-shaped plasma actuator which can emit jet at about 45o through manipulation of the Reynolds stress, meanwhile the alteration for reattachment location over backward facing step. In the process of experiment, The output excitation frequencies for the right-angle-shaped plasma actuator is modulated by the natural instability frequency at 0.5H(H means step height) streamwise positions of the backward-facing step. The region from 0H to 2.5H is measured by PIV(Particle Image Velocimetry), reattachment zone also is measured by PIV. The results showed that when the right-angle-shaped plasma actuator is turned on, the maximum of Reynolds stresses components in the region centered on the shear layer and nearby the shear layer are significantly increased about 42%(< >),75%(< >),46%(-< >), the maximum of turbulent kinetic energy production in region centered on the shear layer is reduced about 11% .The reattachment location is moved upstream in the reattachment zone
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