大型水平轴风力机塔影效应特性研究

Characteristic Study on Tower Shadow Effect of Large-scale Horizontal-axis Wind Turbines

为了研究塔影效应对大型水平轴风力机的影响,选取NREL 5MW风力机作为研究对象,利用Fluent软件对单台风力机的不同工况进行数值模拟。结果表明:塔影效应的影响主要发生在叶片方位角为140°~210°的时域内;当叶片扫掠过塔筒时,其不同周向位置的转矩和轴向推力出现大幅波动,转矩的相对波动幅度随来流风速的减小而减小,叶片所受轴向推力的相对波动幅度随来流风速的减小而增大;由于叶片尖部周向线速度较大,在研究塔影效应时需考虑叶轮旋转效应的影响;对于风力机尾迹流场,旋转半径越大处,塔筒造成的尾迹越明显,其长度约为叶轮直径的2倍。

To study the tower shadow effect on the performance of large-scale horizontal-axis wind turbines, numerical simulations were carried out on a single wind turbine using Fluent software by taking a NREL 5 MW wind turbine as the object of study. Results show that the tower shadow effect mainly occurs in the time domain from azimuth angle 140° to 210°. When the blades are rotating, the tower shadow would cause a significant fluctuation in the torque and axial thrust at different circumferential positions. With the rise of wind speed, the relative fluctuation of torque increases, while that of axial thrust reduces. For large-scale wind turbines, blade tips are working at a high linear velocity, when the rotation effect of rotor should be considered in the process of studying the tower shadow effect. For the wake formed in the downwind of rotor, the larger the rotating radius is, the more obvious the wake will be, and its length is about twice the rotor diameter.