水平轴风力机尾迹流场试验

AN EXPERIMENTAL STUDY OF THE WAKE STRUCTURE OF A MODEL HORIZONTAL-AXIS WIND TURBINE

在水平轴风力机模型不同尖速比条件下,利用旋转单斜丝热线在风轮下游进行尾迹流场速度测量。采用周期性采样和锁相平均技术热线测量技术,获得了风轮下游尾迹三维流场的定量信息,为准确计算风力机的流场、载荷和气动特性等提供了依据。试验结果表明:风轮下游尾迹区内气流存在明显的三维性。尾迹在向风轮下游的发展传播过程中,尾迹中心形成的运动轨迹是与风轮叶片旋转方向相反的螺旋线。尾迹区内的速度亏损随风轮下游轴向位置的增加而减弱,在气流向下游流动的过程中尾迹速度亏损值逐渐衰减,尾迹区的宽度不断扩大,并逐渐与主流掺混融合。尾迹区内相同轴向位置上不同叶高处的速度型相似。在叶片的尾迹区内,流动的紊流强度大大高于周围的非尾迹区,其中紊流强度径向、切向分量较大,轴向分量最小,尾迹区内的紊流具有高度不均匀性。

An experimental study on the properties of the wake in a horizontal-axis wind turbine （HAWT） rotor were earried out at model scale, and the formation and development of the three-dimensional wake were obtained using a single slanted hot-wire probe and phase-locked averaging technique. This task was done at five axial locations within four chord lengths of the blades over a range of tip speed ratios. These data can be taken to identify and better understand the physical attributes of the flow field as well as to aid the accurate prediction of the performance of HAWT. During the downstream development of the wake, the track of the wake centre is a helical curve which rotation direction is opposite to that of the rotor. The distribution of mean velocity behind the HAWT rotor reveals the expansion and decay of the three-dimensional wake. The shapes of the mean velocity distribution are similar along the blades span at the same downstream axial location. It is shown that the non-uniformity and level of turbulence in the wake are relatively higher than that of in the non-wake region. The magnitude of tangential component and radial component of turbulence intensity are higher than that of axial component of turbulence intensity in the wake region.