俯仰风力机翼型动态失速数值模拟

NUMERICAL SIMULATION OF PITCHING WIND TURBINE AIRFOIL DYNAMIC STALL

利用带转捩修正的k-ωSST湍流模型,对绕其1/4弦长点作正弦波周期性振荡的S809翼型,在弦长雷诺数为106,不同的平均攻角、振荡幅度以及折合频率情况下的流场进行二维数值模拟。数值模拟得到的升力、阻力和俯仰力矩系数与OSU风洞试验的数据进行比较,对比显示两者的气动力迟滞闭环具有良好的一致性。利用流线分布对各工况下的动态流场特性以及动态失速涡的发展进行详细描述,证明CFD方法是预测风力机翼型动态失速特性的有效途径之一,分析了动态失速对于实际运行的风力机的影响,说明在风力机性能预估中考虑动态失速影响的必要性。

The unsteady aerodynamic characteristics of the NREL S809 airfoil undergoing sinusoidal pitch oscillations about the quarter chord point at various reduce frequencies, mean angles of attack and pitch oscillation amplitude of about 10° at Re = 106 were investigated through solutions of two dimensional Navier-Stokes equations with transition corrected k-ω SST turbulence model. CFD predicted lift, drag and moment coefficients were compared with the OSU wind tunnel test results, which showed a good agreement between them in the aerodynamic force hys- teresis loops. The dynamic flow characteristics and the development of the dynamic stall vortex were represented in detail through streamlines distribution. CFD solution is proved to be one of the effective methods in prediction of wind turbines airfoil dynamic stall characteristics. The impact of dynamic stall on the practical operation of wind turbines was analyzed and it is necessary to take into consideration in the prediction of wind turbine performance.