垂直轴风力机叶片动态失速数值模拟

利用数值计算方法研究了一种典型的大高径比垂直轴风力机叶片动态失速现象。在验证数值计算方法可靠的基础上,结合速度矢量图和涡量图,研究了8 m/s风速时风力机在不同尖速比下叶片动态失速现象以及风轮尺寸改变时风轮动态失速流场及其对风力机功率系数的影响规律。研究表明,尖速比过低,增大弦径比和叶片数均导致叶片动态失速和气流分离呈现加剧趋势,削弱风力机的气动性能。对用于城市风力发电的大高径比垂直轴风力机,应使其在最佳尖速比下运行,同时控制弦径比在0.2~0.4之间,叶片数为3或4,以获得较好的气动性能。

Numerical Study on Blade Dynamic Stall of Vertical Axis Wind Turbine

The blade dynamic stall behavior of a vertical axis wind turbine with high height to radius ratio was studied using a numerical method. The numerical modeling technique reliability was validated through a comparison of the computational results with the wind tunnel measurement. Below constant wind condition 8m/s, combined with the velocity vector and vorticity contours, the dynamic stall behavior and the rotor power performance were investigated with different tip speed ratios and variant turbine configurations. Illustrated by the simulation, lowering the tip speed ratio and increasing the rotor cord to radius ratio and the blade number will enhance the vortex generation and the flow separation on blades, leading to significant degradation of turbine performance. It can be concluded from the numerical analysis, a vertical axis wind turbine with high height to radius ratio applied in urban area will experience a better performance when operating in the optimal tip speed ratio, with rotor cord to radius ratio between 0.2 and 0.4, and 3 or 4 blades.