射频介质阻挡放电改善NACA 0015翼型气动性能的实验

Experiment on Improving Aerodynamic Performance of NACA 0015 Airfoil by RF Dielectric Barrier Discharge

介质阻挡放电(DBD)均匀稳定、易于敷设,是机翼/翼型等离子体流动控制(PFC)中最常用的激励方式。射频介质阻挡放电激励频率高、放电功率大,且能在流场中产生明显的加热,应用潜力大。采用射频电源驱动DBD激励器产生等离子体,分析放电的体积力、热特性和诱导流场特性,开展了射频介质阻挡放电改善NACA 0015翼型气动性能的实验,研究了占空比、调制频率、载波频率和电源功率等参数对流动控制效果的影响规律。结果表明:射频等离子体激励的体积力效应随激励电压的增大而增加;射频等离子体激励产生的热量在诱导的流场中进行传导,加速流场;当来流速度为20m/s,Re=3.36×10~5时,在翼型前缘施加激励,使翼型临界失速迎角推迟1°,最大升力系数增大6.43%,且在过失速迎角下仍具有流动控制效果,使升力下降变缓;调制频率越大,控制效果越好;存在最佳占空比、载波频率和功率,占空比对流场控制效果的影响最显著,最佳占空比、载波频率和功率分别为20%,460kHz和50W。射频等离子体激励以体积力效应、热效应和诱导壁面射流改善失速流场,使得NACA0015翼型气动性能极大改善,流动分离得到有效控制。

Dielectric barrier discharge(DBD)is uniform,stable,and easy to lay,and is the most common excitation method in wing/airfoil plasma flow control(PFC). RF dielectric barrier discharge excitation possesses the abilities of high frequency and large discharge power,and can produce obvious heating in the flow field,which has great application potential. RF power was supplied to drive DBD actuator to generate plasma. The body force,thermal and induced flow filed characteristics of discharge were analyzed and the experiment of RF dielectric barrier discharge for improving the aerodynamic performance of NACA 0015 airfoil was carried out. The influence law of duty cycle,modulation frequency,carrier frequency,and power supply on flow control effect was studied. The results show that the body force effect of RF plasma excitation increases with the increase of excitation voltage,and the heat generated by RF plasma excitation is transmitted into the induced flow field to accelerate the flow field. When the inflow velocity is 20 m/s and Reynolds number is 3.36×10~5,the application of RF plasma actuation at the leading edge of the airfoil can effectively delay the 1° of the critical stall angle of attack and increase the maximum lift coefficient by 6.43%. There is still a flow control effect under the over-stall angle of attack,so that the lift coefficient is slowed down. The greater the modulation frequency,the better the control effect. There are optimal duty cycle,carrier frequency and power. The duty cycle has the most significant influence on the control effect of flow field. The optimal duty cycle,carrier frequency and power are 20%,460 kHz and 50 W,respectively. RF plasma excitation improves stall flow field by body force effect,thermal effect,and induced wall jet,which greatly improves aerodynamic performance of NACA 0015 airfoil and effectively controls flow separation.