振荡射流控制方柱绕流的实验研究

为研究振荡射流对方柱绕流的流动控制效果，利用粒子图像测速技术(Particle Image Velocimetry, PIV)分别测量了不同动量系数下布置于前驻点和后驻点的振荡射流控制的方柱绕流流场，并对测得的流场进行本征正交分解(Proper Orthogonal Decomposition, POD)。研究表明：两种布置方式下振荡射流与流场的作用方式不同，均可有效控制方柱绕流流场，且存在着使控制效果达到最佳的动量系数。当位于前驻点的振荡射流动量系数为0.309时，方柱下游流场形态明显改变，尾涡长度减小约50%,湍动能和雷诺剪切应力分别减小约71%和62%,POD模态表明尾涡呈反对称脱落模式；当位于后驻点的振荡射流动量系数为0.174时，尾涡基本消失，此时尾流场湍动能和雷诺剪切应力分别减小32%和67%,POD模态表明尾涡改变为对称脱落模式。

Experimental Study on Sweeping Jet Control of Flow around a Square Cylinder

In order to study the flow control effect of sweeping jet around the square cylinder, the flow field around the square cylinder controlled by the sweeping jet arranged at the front and rear stagnation points under different momentum coefficients was measured by particle image velocimetry (PIV). And the proper orthogonal decomposition (POD) was used to analyze the measured flow field. The results show that the interactions of the sweeping jet and the flow field are different under the two arrangements, but both arrangements can control the flow field around the square cylinder effectively, which have an optimal momentum coefficient that achieves the best control effect. When the momentum coefficient of sweeping jets at the front stagnation point is 0.309, the shape of the flow field downstream of the square cylinder changes significantly, the wake vortex length, the turbulent kinetic energy and Reynolds shear stress decrease by about 50%, 71% and 62%, respectively. POD modes show that the wake vortices shed downstream antisymmetrically. When the momentum coefficient of sweeping jets at the rear stagnation point is 0.174, the wake vortices are basically eliminated, and the turbulent kinetic energy and the Reynolds shear stress of the wake flow field are reduced by 32% and 67%. POD modes show that the wake vortices change to shed downstream symmetrically.