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采用三维粒子图像测速方法(SPIV),研究两种不同尖速比下的水平轴风力机叶尖涡演变过程及尾流速度流场特性。通过锁相技术,首次实现风力机下游远至2.7倍直径范围内的尾流数据采集,完整揭示叶尖涡发展湮灭的过程及其对尾流流场的影响。尾流轴向速度呈先减小至最大尾流衰减率后再逐渐恢复的规律,且发生该最大衰减率的位置与叶尖涡的运动密切相关;分析叶尖涡对尾流速度恢复的阻滞作用,提出以叶尖涡“交替跳跃”现象作为风力机近、远尾流区分界点标志的依据;在此基础上推导风力机近尾流区长度的计算公式。
Using three-dimensional particle image velocimetry (SPIV) method, the evolution process of tip vortex and wake flow field characteristics of two horizontal axis wind turbines with different speed ratios are studied. By phase-locked technology, the wake data acquisition in the range of up to 2.7 times as far as the wind turbine downstream is realized for the first time, which fully reveals the process of annihilation of the tip vortex and its effect on wake flow field. The wake axial velocity decreases first to the maximum wake decay rate and then gradually regains, and the position where the maximum decay rate occurs is closely related to the movement of tip vortex. Analyzing the resistance of tip vortex to the recovery of wake velocity It is proposed that the tip vortex “alternate jump ” be used as the basis for the marker of the boundary point between the wind turbine and the far wake. Based on this, the formula for calculating the length of the wake near the wind turbine is derived.