纳秒脉冲等离子体激励控制小后掠三角翼低速绕流试验

Experiment of flow control on a low swept delta wing using pulsed nanosecond plasma actuation

为探索纳秒脉冲介质阻挡放电（NS DBD）对小后掠尖前缘三角翼的流动控制效果和作用机理,进行NS DBD用于改善其气动特性的测力试验和流动显示试验。当来流速度分别为30m/s和45m/s时,测力试验结果表明位于机翼前缘的NS DBD能很好地改善三角翼大迎角气动特性,其中来流速度为45m/s时最大升力系数提高了18.3%;研究了脉冲激励频率对流动控制效果的影响规律,最佳的无量纲激励频率F^＋≈1～2。在来流速度为20m/s时,采用粒子图像测速仪（PIV）研究了不同迎角下激励前后机翼背风面流场,表明NS DBD可改善上翼面旋涡结构,使分离涡附体并得到加强。基于试验结果,认为NS DBD进行三角翼前缘涡控制的机理是激励诱导分离剪切层周期性产生附体的分离涡,从而维持了上翼面大迎角时的涡升力。

In order to explore the flow control effect and mechanism of nanosecond dielectric barrier discharge （NS DBD） on the low swept delta wing with sharp leading edge, force measurements and flow visualization experiments are conducted on a 30° swept delta wing. When the flow speed is 30 m/s and 45 m/s, it is found that leading-edge plasma actuation can sig- nificantly improve the aerodynamics of delta wing at a high angle of attack, with the maximum lift coefficient increased by about 18.3%. The influence law of the actuation frequency on the control effect is investigated, that is the optimum reduced frequency of F^＋≈1 to 2. When the flow speed is 20 m/s, particle image velocimetry （PIV） measurement is conducted to investigate the formation of leading edge vortices affected by the pulsed NS DBD at different angles of attack. The flow pattern obtained from the PIV measurement shows that flow reattachment is promoted by excitation, and an intensified vortex flow pattern develops. Based on the experimental results, it is supposed that the reforming of leading-edge vortex, resulting from periodic emanation of small-scale vortices moving along the shear layer due to the pulsed actuation, may be the mechanism.