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中文核心期刊

基于等离子体激励的两段翼型阵风减缓控制研究

TWO-ELEMENT AIRFOIL GUST ALLEVIATION USING A PLASMA ACTUATOR

  • 摘要: 介质阻挡放电等离子体流动控制技术是基于等离子体激励的主动流动控制技术, 具有响应时间短、结构简单、能耗低及不需要额外气源装置等优点, 在飞行器增升减阻、抑振降噪和助燃防冰等方面具有广阔的应用前景. 在延长无人机滞空时间和促进低空无人机发展的背景下, 以GAW-1两段翼型为研究对象, 以正弦交流电压激励下的介质阻挡放电等离子体激励器为控制方式, 采用数值模拟方法开展了基于介质阻挡放电等离子体激励的1-cos型阵风减缓研究, 评估了等离子体控制效果, 揭示了等离子体阵风减缓机理. 在计算时, 将单个非对称布局介质阻挡放电等离子体激励器布置在翼型尾缘处, 激励器诱导的准定常射流的方向与来流相反. 结果表明: (1)施加等离子体激励后, 升力系数的波动量最大减小了51.6%, 自下而上型阵风对翼型的影响大幅减缓; (2)等离子体激励能够增大边界层形状因子、延长分离区长度和增加分离区面积; (3)等离子体诱导射流与诱导涡是实现阵风减缓的关键. 诱导的逆向射流通过阻碍来流发展、引射下翼面流线加速并向上偏转的方式, 减小了上下翼面的压力差, 从而降低了升力系数; 而诱导涡形成的“虚拟凸起”进一步扩大了分离区面积. 研究结果为提升低空无人机气动性能提供了技术支撑.

     

    Abstract: Flow control technology using dielectric barrier discharge (DBD) plasma actuators is an active flow control technology based on plasma actuation and has some advantages, such as short response time, simple structure, low consumption power, and no need for additional air source devices. Motivated by the demand of improving the endurance performance and promoting the development of low altitude unmanned aerial vehicles (UAV), the investigations on a two-element airfoil of GAW-1 gust alleviation by using a DBD plasma actuator driven by a sinusoidal alternating current (AC) were carried out with the help of numerical simulation method. The control effect of DBD plasma actuator was evaluated by aerodynamic forces and the gust alleviation mechanism was uncovered by instantaneous flow fields. An asymmetrical DBD plasma actuator was placed at the trailing-edge of airfoil and the direction of the quasi-steady wall jet produced by the plasma actuator was opposite to the incoming flow. The maximum reduction of the fluctuation of lift coefficient was approximately 51.6% after applying the DBD plasma actuation, which indicated that the effect of gust on the airfoil can be weaken effectively by the plasma actuator. In addition, the shape factor of boundary layer was increased, the length and the area of separation zone was prolonged and was extended, respectively, with the help of plasma actuator. Moreover, it is believed that the wall jet and the vortex both created by the plasma actuator play an important role in gust alleviation. The pressure difference between the upper and lower airfoil surfaces was reduced by the induced wall jet which hindered the development of incoming flow, accelerated and deflected the streamline of the lower airfoil surface deflect upwards, leading to reduce the lift coefficient of airfoil. Meanwhile, a virtual hump generated by the induced vortex expanded the area of separation zone. The present results lay a technical foundation for promoting the aerodynamic performance of low altitude UAV.

     

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