叶片旋向对风力机尾流特性影响的试验研究

EXPERIMENTAL STUDY ON INFLUENCE OF BLADE ROTATION ON WAKE CHARACTERISTICS OF WIND TURBINE

采用一种简单、有效的方法来改善风力机尾流效应,提升下游风力机功率。进行叶片旋向对风力机尾流特性的试验研究,利用低频粒子图像测速(PIV)系统对NACA4415翼型的叶片进行扰流流场测试并采集风力机的尾流数据。当2台串列排布的风力机旋向不同时,首先在下游风力机前1D(D为风轮直径)处,叶尖涡涡核位置向中央尾迹区偏移,而外部主流区的流体在叶尖涡诱导区的输运和卷吸作用下持续进入中央尾迹区并与之掺混使得轴向速度恢复得更佳;进而分析下游风力机后1D的流场数据,结果显示:虽然下游风力机叶尖涡几何结构被“打碎”,但涡核能量却未降低;最后探讨影响风力机功率特性的因素,下游风力机入流角的增大促使下游风力机捕获更多风能,在风轮间距为2D时,逆向旋转的功率比比同向旋转时高4.70%,且功率比随间距增加其增幅逐渐减小。

In this paper,a simple and effective method was used to improve the wake effect of the wind turbine and increase the power of the downstream wind turbine.An experiment was carried out to investigate the influence of different rotation directions of the blade on the wake of the wind turbine.The low-frequency PIV system was used to test the turbulence flow field produced by the NACA4415 airfoil and collect the data of the wake of the wind turbine.As the results,when two wind turbines arranged in tandem have different rotation directions,at the 1D(D is the diameter of the wind turbine)in front of the downstream wind turbine,the position of the tip vortex core shifts to the central wake region.And the flow in the external main region,due to the inducible effect,is sucked into the central wake region and blended with its flow,speeding up the axial velocity.For the 1D flow field data of the downstream wind turbine,the results show that the vortex core energy does not decrease,even though geometry structure of blade-tip vortex of the wind turbine downstream is“broken”.Finally,the factors affecting the power characteristics of wind turbines are discussed.The result shows that with the increase of the inflow angle of the downstream wind turbine,more wind energy can be captured.When the distance between the wind turbines is 2D and the blades rotate counterclockwise,the power ratio is 4.70%higher than that rotate clockwise,and the increase of the power ratio gradually decreases with the increase of the distance.