等离子体激励对低雷诺数下翼型层流分离特性的影响及机理研究

低雷诺数下翼型气动性能的改善对滑翔机、高空无人飞行器、直升机、微型飞行器、风力机等性能的提升有着重要的意义。当基于弦长的雷诺数低于200,000 时，翼型上会出现升力在零度附近随迎角非线性变化、最大升阻比迅速降低、力/力矩随迎角变化出现静态滞回等典型的低雷诺数空气动力学问题。当选取的翼型几何外形确定后，如何通过有效的流动控制技术来改善其在低雷诺数下的气动力特性是航空领域期待解决的问题。等离子体流动控制具有小体积、灵活多样、易于大面积放置的激励器，还具有宽频、小能量和高效率的电学特性。本项目通过正弦交流与纳秒脉冲两种不同介质阻挡放电等离子体激励，对选取的典型翼型进行流动控制风洞实验研究，通过对低雷诺数下翼型上广泛存在的前缘/后缘层流分离泡进行控制，期望对翼型气动力特性产生好的影响。通过对等离子体激励下层流分离泡的瞬时与时均形态的变化的研究给出流动控制机理解释。

There has been an increasing interest in the design and performance of airfoils operating in low Reynolds number flows. This interest has been a result of the desire to improve the low-speed performance of high-aspect-ratio sail plane wings, unmanned aerial vehicles, ultra-light micro-aircrafts, and wind turbine blades. Many significant aerodynamic problems including nonlinearities in the lift-curve characteristics, undesirable sharp decrease in lift-to-drag ratio, and static hysteresis in the section lift, drag and moment data appear to occur below chord Reynolds numbers of about 200,000. How the low Reynolds number performance of airfoils could be improved has been an urgent problem in the field of aeronautical engineering. Flow control with plasma has received growing attention because of its less space occupation, flexibility, broader frequency bandwidths, relatively low energy consumption and high efficiency. Based on the aforementioned background, the primary objective of the present research is to obtain the effects of dielectric barrier discharge plasma actuators on separation control of laminar boundary layer bubble over the specific airfoils with the wind tunnel testing methodology. Both Alternating Current (AC-) and Nanosecond Pulse (NS-) driven plasma will be examined in order to eliminate or control the laminar separation bubbles as well as improving the low Reynolds number performance of these specific airfoils. A deeper insight into the underlying physical mechanisms will be obtained by studying the time-averaged and instantaneous structure and dynamics of the laminar separation bubbles.