以100 W水平轴风力机为研究对象,利用三维超声波风速仪在风轮下游进行尾迹流场的速度测量.采用超声波时差法,获得风轮下游的三维尾流场信息.实验结果表明:风轮下游尾迹区内的流动 存在明显的三维特性.由于风轮旋转和来流衰减,使得风力机尾迹区轴向速度存在严重的亏损,且尾迹区轴向速度亏损随着风轮下游轴向距离的增大逐渐减弱.但由于风轮旋转时叶尖涡脱落,在距测量中心径 向较远处出现高速度区域.径向速度和切向速度在3倍风轮直径截面处最大,随着轴向距离的增大逐渐减小,且径向速度和切向速度的波动频率随着径向距离的增大逐渐减小.尾流场的湍流强度在风轮旋转半 径内高于半径外,随着轴向距离的增大,湍流度先增大后减小,在远尾流区与大气来流逐渐融合,且流动逐渐趋于稳定,在8倍风轮直径位置处适合布置下游风力机.%Taking 100 W horizontal-axis wind turbine as investigation object and using three-dimensional ultrasonic anemometer as instrumentation, the velocity measurement of flow field of wake downstream behind turbine rotor is conducted.The ultrasonic time-difference method is used to obtain the three-dimensional flow field information of wake downstream behind the turbine rotor.The experimental results show that the flow in wake zone exhibits obvious three-dimensional characteristics.Within wind turbine wake region, the axial speed will be made decreased seriously due to turbine rotor rotation and oncoming flow attenuation, and the speed loss will be decreased gradually with the axial distance from turbine rotor.However, there will be high velocity in the distant region from the center of the measurement caused by the shedding of vortex at the blade tip of rotating turbine rotor.Radial velocity and tangential velocity are the largest in three times rotor diameter section and with the increase of the axial distance from the rotor, they will decrease gradually.In addition, the fluctuation frequency of the radial velocity and tangential velocity will decrease gradually as well with the increase of the radial distance.Turbulence intensity of flow field of wake will be higher in the region within rotor rotating radius than that outside it.The turbulence degree will increase first and then decrease with the increase of the axial distance and the atmospheric oncoming flow outside the wake will gradually mix with it in the far wake region and the flow will tend to be stable.At the position of eight times rotor diameter distance behind the up wind turbine the downstream turbine can be installed suitably.
展开▼
