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中文核心期刊

风剪切对风力机叶片气动性能及尾迹形状的影响

INFLUENCE OF WIND SHEAR ON AERODYNAMIC CHARACTERISTICS AND WAKE SHAPE OF WIND TURBINE BLADES

  • 摘要: 风力机通常运行在非定常工况中,其气动性能及尾迹会随着工况的变化而变化. 风剪切是风力机长期所处的环境,它会影响到叶片气动载荷、尾迹形状、总体性能等,分析风剪切作用下的叶片气动性能对风力机的设计有重要意义.本文采用一种时间步进自由涡尾迹(free vortex wake, FVW)方法,耦合FVW方法与风剪切模型,计算不同风剪切因子作用下叶片的气动力系数、推力以及风轮后的尾迹形状变化,研究尾迹形状变化对风轮旋转平面诱导速度及风力机叶片气动性能的影响. 结果表明:在风剪切入流条件下, 随着风剪切因子的增大,风力机的气动力系数随时间做周期性波动的幅度加剧, 推力的平均值逐渐减小,尾迹倾斜程度增大, 尾迹在轮毂下方的倾斜程度更明显;尾迹形状的变化使风轮平面轴向诱导速度因子分布不均匀,同时使风力机的总体性能降低且偏离较大;倾斜尾迹相比于对称尾迹对风轮平面处的诱导影响有明显差别, 波动幅值增大,气动力系数在波谷处的偏差比波峰处大. 尾迹越倾斜,风轮旋转平面处的载荷不对称性越明显.

     

    Abstract: A wind turbine usually operates in unsteady conditions, and the aerodynamic performance and wake of the rotor will change with the change of working conditions. Wind shear is the most common and long-term environment of wind turbine. It often affects the aerodynamic load, the shape of the wake and the overall performance of the wind turbine. So it is important to analyze the aerodynamic performance of blade of the wind turbine under the wind shear condition. In this paper, a time-marching free vortex wake method, which coupled with the wind shear model, is used to calculate the aerodynamic coefficient, thrust and wake shape change under different wind shear factors. At the same time, the influence of the wake shape variation on the induced velocity of the rotor rotating plane and the aerodynamic performance of the wind turbine blade are studied. The results show that: under the condition of wind shear inflow, with the increase of the wind shear factor, the fluctuation amplitude of aerodynamic coefficient of the wind turbine, which fluctuates periodically with time is increased, the average thrust decreases gradually, the tilted degree of wake increases and the tilted degree of wake under the center of hub is more obvious. The distortion of wake shape makes the distribution of the axial induced velocity factor in the rotational plane uneven, and makes the overall performance of wind turbine decrease and deviate greatly. There is a distinct difference of the induced effect on the rotational plane between the tilted wake and the symmetrical wake. The fluctuation amplitude of the aerodynamic coefficient induced by the tilted wake is larger than that induced by the symmetrical wake, and the deviation of the wave trough is more obvious than the wave crest. The more tilted the wake is, the more obvious the load asymmetry in the rotating plane is.

     

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