不同迎角下前体涡流动的等离子体控制特性

应用一对单介质阻挡放电等离子体激励器对20°顶角圆锥-圆柱组合体圆锥段分离涡流场进行了主动控制研究。实验在3.0 m×1.6 m低速风洞中进行,迎角35°～70°,基于圆锥段底面直径的雷诺数为5.0×104。实验结果包括7个测量截面周向压力分布、由周向压力分布推断得到的截面处空间涡结构以及积分得到的截面当地力和圆锥段力。实验结果表明:(1)在35°～50°迎角范围内,圆锥段流场只有一对非对称的主涡,圆锥段分离涡流动呈现近似锥型流特性,随着迎角增大,圆锥段侧向力系数符号不变;(2)在50°～70°迎角范围内,圆锥段流场呈现多涡结构,圆锥段分离涡流动不再呈现锥型流特性,此时随着迎角增大,圆锥段侧向力系数会发生多次变号;(3)等离子体控制使得圆锥段对涡流场中第1个新涡出现的迎角推迟。

Exploring Flow Features of Conical Forebody Versus Angle of Attack under Plasma Actuation

A pressure measurement experimental study of the active control of vortices over slender forebodies was performed on a 20° circular cone forebody using a pair of Single-Dielectric Barrier Discharge(SDBD) plasma actuators.Section 1 of the full paper explains our exploration mentioned in the title.Its core consists of: "The tests were performed in the NWPU low-turbulence 3.0 m×1.6 m low-speed wind tunnel at angles of attack of 35°~70°.The Reynolds number based on the base diameter of the circular cone is 50 000.The results consist of detailed pressure distributions over seven stations along the cone with and without plasma control.From the measured pressures,the local side forces over the cone are calculated and the vortex patterns are inferred." The experimental results,presented in Figs.3 through 7 and Table 1,and their analysis indicate preliminarily that:(1) at the angles of attack of 35°~50°,there exists just a pair of primary asymmetric vortices,the flowfields are the nearly conical flow;with increased angles of attack,the overall side force remains of the same sign;(2) at the angles of attack of 50°~70°,the flowfields are no longer the conical flow and a multi-vortex pattern occurs;with increased angles of attack,the overall side force experiences the sign change several times;(3) the occurrence of the first additional vortex besides the initial vortex pair is delayed to a higher angle of attack due to the plasma actuation.