考虑不确定性的风力机翼型颤振边界研究

Research on Flutter Boundary of Wind Turbine Airfoil Considering Uncertainties

随着风力机叶片长度不断增加,其柔性增加,气弹稳定性下降。准确判别叶片气弹稳定性边界对叶片设计具有重要意义。然而,风力机现实工作环境存在不确定性的随机影响因素,使得叶片气弹稳定性边界不是确定值。基于OpenFOAM求解器,对FFA-W3-241翼型的动态失速过程进行了数值模拟,通过能量法找寻翼型俯仰与沉浮耦合运动下的颤振边界;采用基于稀疏网格法的多项式混沌方法对耦合运动进行了不确定性量化分析。结果表明,在轻度失速工况下翼型颤振边界不明确,考虑不确定因素为俯仰平均攻角、俯仰攻角振幅、俯仰折合频率、沉浮距离振幅、沉浮折合频率后,翼型发生颤振的概率为49.48%。此外,颤振发生对俯仰折合频率的敏感度最高,其次是沉浮折合频率,而沉浮距离振幅、攻角振幅对颤振的影响较小。

As the length of wind turbine blade increasing, the flexibility grows and the air-elastic stability decreases. Accurately identifying the blade air-elastic stability boundary is of great significance to blade design. However, the wind turbine works in a random environment with uncertainty, which makes the blade air-elastic stability boundary not a definite value. In this paper, the dynamic stall process of FFA-W3-241 airfoil is simulated numerically based on OpenFOAM solver, and the flutter boundary under the coupled pitch and plunge motion is located through the energy method;a sparse grid-based polynomial chaos method is used to quantify the uncertainty impact for the coupled motion. The results show that airfoil flutter boundary is not clear under the slight stall condition, and the probability of flutter onset is 49.48% when considering the uncertainties as the mean and amplitude of pitch angle of attack, pitch reduced frequency, plunge amplitude, and plunge reduced frequency. In addition, the sensitivity of flutter to pitch reduced frequency is the highest, followed by plunge reduced frequency. While the influence of plunge amplitude on flutter is relatively small.