基于CFD技术的垂直轴风力机动态尾流特性研究

利用CFD软件对麦克马斯特大学垂直轴风力机进行不同叶尖速比下的数值模拟,计算结果与风洞试验数据吻合良好。近场尾流中,与单叶片的风力机模拟结果比较,上游叶片产生并向下游延伸的旋涡影响下游运行轨道上叶片的升阻力特性,不仅使叶片扭矩输出峰值降低,而且峰值产生的时间延迟。对垂直轴风力机叶片叶梢进行修改,模拟结果显示,叶片扭矩输出峰值不变,但是谷值有所降低,修改后风力机沿风向推力幅值降低明显;远场尾流中,采用风速轮廓线原理,以瑞典的法尔肯贝里市200kW垂直轴风力机为原型,按照真实的空间排布进行数值模拟。模拟结果显示,上游风力机上下两端处产生较为集中的远场尾流,影响下游风力机叶片下半段的气动性能,下游风力机功率输出降低明显。

Analysis of vertical axis wind turbine dynamic wake with CFD technology

The simulation of the vertical axis wind turbine which was designed by McMaster University is conducted under various tip speed ratio with the CFD software,and the results agree well with the wind tunnel experiments.In the near wake,comparing with the turbine with only one blade,the dragged blade tip eddies of the upwind blade in normal running wind turbine influences the downwind blade's aerodynamic characters:not only declines its peak value of the torsion torque,but also delays its occurrence time.The modified wind turbine has equal peak torsion torque value output with normal turbine,but less valley value,and the modified one produces less pushing force parallel to the wind; in the far wake,the wind profile theory was added into the simulation of the 200kW vertical axis wind turbines in the wind farm of Falkenberg,Sweden.The results reveal the upwind wind turbine produced intensive far wake flow in the upper and lower ends of the blades,and the downwind turbine' aerodynamic character was affected in the lower half parts of the blades.Influenced by the far wake in the wind farm,the downwind turbine produces less energy.