等离子体环量控制翼型增升的实验研究

EXPERIMENTAL INVESTIGATION ON LIFT INCREMENT OF A PLASMA CIRCULATION CONTROL AIRFOIL

利用等离子体激励器发展了新型的环量增升技术,并对二维NACA0012翼型绕流实施控制.由于NACA0012翼型为尖后缘构型,环量增升装置由2个非对称型介质阻挡放电等离子体激励器构成.一个等离子体激励器贴附于翼型吸力面靠近后缘处,其诱导的壁面射流沿来流方向指向下游;另一个等离子体激励器贴附于翼型压力面靠近后缘处,其诱导的壁面射流与来流方向相反指向上游.在风洞中通过时间解析二维PIV系统对翼型绕流流场进行了测量,基于翼型弦长的雷诺数Re=20000.结果表明在等离子体激励器的控制下,翼型压力面靠近后缘处可以形成一个定常回流区,从而起到虚拟气动外形的作用,因此翼型吸力面的流场得到加速,压力面的流场得到减速,使得翼型压力面的吸力以及压力面的压力都得到增加,进而增加了翼型的环量.风洞天平测力实验进一步验证了该环量增升技术的有效性.在整个攻角范围内,施加控制的翼型的升力系数相比没有控制的工况有明显的提高.

Based on the flow characteristics of the dielectric-barrier-discharge （DBD） plasma actuator, a novel circulation control technique has been proposed, which is used to control flow around a NACA0012 airfoil. Since the trailing edge of the NACA0012 airfoil is not a circular surface, the circulation control technique is constructed from two DBD plasma actuators. One is attached to the suction surface near the trailing edge, with its induced wall jetto the same direction with the free stream. The other is attached to the pressure surface near the trailing edge, with its induced wall jet to the opposite direction with the free stream. Time-resolved PIV is employed to measure the velocity field in the near-wake region, with the Reynolds number based on the airfoil chord length Re = 20 000. With the plasma circulation control, a steady recirculation region could be formed on the pressure surface near the trailing edge, acting as the virtual aeroshaping effect, thus the flow over the suction surface is accelerated, while the velocity over the pressure surface is reduced. Thus both the suction and pressure over the airfoil are enhanced, increasing the circulation over the airfoil. The dynamic force balance measurements further validate the efficiency of the lift improvement by the present plasma circulation control. The plasma control increases the lift coefficients over the entire angles of attack.