在直流式低速风洞中,应用PIV系统对水平轴风力机的中心尾迹区进行测试,揭示了在不同风速及不同尖速比下,气流通过风轮时叶片中央尾迹区流场的运动规律。通过实验发现,风经过风轮后,由于动量损失和涡流诱导效应,风轮中心尾迹区内部流场速度减小,外部流场轴向速度增加,在风轮机舱处形成强速度梯度区域。随着方位角的增大,中心涡的轴向传播距离逐渐减小。随着中心尾迹的延伸,中心涡的运动轨迹逐渐扩散,即径向位移是逐渐增加的,且涡量逐渐减小。中心涡在中心尾迹区的径向影响范围大约为风轮直径的0.42倍,轴向影响范围大约为风轮直径的0.58倍。
The motion characteristics of the airflow at wake flow field under different wind velocity was carried out by using particle image velocitmetry (PIV) system in a horizontal axis wind turbine at low wind speed. The experiments shows that after the airflow through the wind wheel, due to momentum loss and the induced eddy current effect~ the flow field of the wind round the central wake area decreases and the axial velocity of external flow field increases and A strong velocity gradient zone at the cabin of the wind turbine was formed. The axial propagation distance of the center vortices graduMly decreases with the increasing of azimuthal. As an extension of the wake in the center, the trajectory of the center vortex gradually spread, ie, radial displacement is gradually in- creased, and the vorticity is gradually reduced. The influence scope of the vortex center wake is about 0.42 times of the diameter of the rotor at radial area and 0.58 times of the diameter of the rotor at axial.