低空急流条件下水平轴风力机风轮气动特性的研究

为阐明低空急流条件下风力机风轮的气动特性,基于工程化的边界层风速模型和Von Karman谱模型建立不同来流的脉动风场,对比研究低空急流条件下NREL 5 MW风力机风轮的输出功率和气动载荷的变化规律。结果表明:如果仅以轮毂高度处的风速作为风力机变桨控制的依据,与均匀来流和剪切来流相比较,低空急流条件下,虽然来流风功率明显增大,但风轮的输出功率在较高风速时反而减小;风轮所受的不平衡气动载荷,包括横向力、纵向力、偏航力矩和倾覆力矩在较高风速时小于剪切来流的结果;且仅以轮毂高度处的风速预测得到的风轮输出功率高于实际结果,其最大相对误差为89.4%。因此,低空急流条件下,为提高风能利用率和风轮输出功率的预测精度,应考虑不同高度位置处的风速大小对风力机进行变桨控制和功率预测。

STUDY ON AERODYNAMIC CHARACTERISTICS OF HORIZONTAL AXIS WIND TURBINE UNDER LOW-LEVEL JET INFLOW CONDITION

In order to clarify the aerodynamic characteristics of the wind turbine rotor under Low-level Jet(LLJ)inflow condition,the different turbulent wind fields were established based on the engineered boundary layer wind speed model and Von Karman spectrum model. The output power and aerodynamic loads of the NREL 5 MW wind turbine rotor were studied under LLJ inflow conditions by comparison with the results under the uniform and shear inflow condition. The results show that if the blade pitch control is only based on the wind speed at the hub-height,although the incoming wind power is significantly increased under LLJ inflow condition,the output power of the rotor is reduced compared with the results under uniform and shear inflow condition at higher wind speeds. The unbalanced aerodynamic loads exerting on the rotor,including lateral force,longitudinal force,yaw moment and tilt moment,are less than results under shear inflow condition at higher wind speeds. In addition,the output power of the rotor predicted from the wind speed at the hubheight is higher than the actual result,and the maximum relative error is 89.4%. Therefore,under LLJ inflow conditions,in order to improve the wind energy utilization rate and the forecasting accuracy of the rotor output power,the wind speed at different heights should be taken into account when the rotor blade control and power prediction are carried out.