多路等离子体合成射流改善翼型性能实验研究

Experimental Investigation of Enhancing Airfoil Aerodynamic Performance with Multichannel Plasma Synthetic Jet

关键词:  等离子体合成射流  高升力翼型  流动分离  多路放电

Key words:  Plasma synthetic jet  High-lift airfoil  Flow separation  Multichannel discharge

摘要:

等离子体合成射流(PSJ)响应快，频带宽，强度大，在飞行器增升减阻领域具有广阔应用前景。但常规等离子体合成射流只是单点激励，作用范围小，控制效果弱。为提高等离子体合成射流抑制机翼流动分离的能力，设计了一种新型多路放电电路驱动合成射流，使单个电源产生5～12路多点、高强度合成射流激励，并将其用于高升力翼型失速分离控制。研究了激励频率、电容能量、来流速度和激励位置对流动控制效果的影响以及阵列式激励的控制规律。实验结果表明:12路PSJs各路均能产生较强的冲击波和射流，能有效抑制翼型吸力面的流动分离，增加升力，推迟失速；当激励频率为150Hz使无量纲频率等于4.8时，流动控制效果最好；电容能量越大，来流速度越小，流动控制效果越好；翼型距前缘15%c处为最佳激励位置，在主翼后缘施加激励与前缘激励类似，能有效抑制主翼流动分离；在主翼前缘和后缘同时施加激励，增升效果变强，推迟失速的能力降低。流场存在延迟效应，延迟时间不小于585s。

Abstract:

Plasma synthetic jet (PSJ) has fast response， broad frequency band and great intensity with vast application prospects in lift enhancement and drag reduction of aircrafts. But conventional plasma synthetic jet can only work at one point with limited actuating range and control effect. To improve the capability of PSJ to suppress flow separation on airfoil， a new multichannel discharge circuit was designed to drive plasma synthetic jet actuators (PSJAs) and 5～12 PSJAs were driven with high strength by one power supply， which was used in flow separation control of a high-lift airfoil. The effects of actuation frequency， capacitance energy， free stream velocity and actuation location on the flow control results were investigated and the control rule of PSJ array was explored. Results show that， every channel of 12 channels’ PSJs can produce strong shock wave and jet flow， which suppress flow separation on the suction side of airfoil and increase lift and stall angle. The best flow control effect appears when actuation frequency is 150Hz with reduced frequency equal to 4.8. There are better flow control effects with greater capacitance energy and smaller free stream velocity and the best actuation location is 15%c downstream of the leading edge. Actuation at the trailing edge of main wing has similar effect as leading edge actuation， suppressing flow separation effectively while exerting actuation at both leading edge and tailing edge can increase more lift and less stall angle. There is also hysteresis effect with hysteresis time greater than 585s.