叶尖小翼对风力机气动性能的影响分析

Effect of Tip Winglet on Aerodynamic Performance of Wind Turbine

叶片作为风能捕获装置,其气动性能决定着风力机的风能利用效率。为有效提升风力机在低风速条件下的风能捕获能力,借鉴飞机在机翼翼尖添加小翼提升气动性能的设计理念,对风力机叶片叶尖添加后掠L型叶尖小翼,并采用标准的k-ε湍流模型对加装小翼叶片和原型叶片在不同风速条件下进行3维流场的数值模拟研究。结果表明:与原型叶片相比,后掠L型叶尖小翼对通过叶尖区域的气流有导流作用,改善了叶尖气流的流动形态,使通过叶尖的气流变得平缓流畅,有效减小了叶尖处的诱导阻力,阻断了叶尖处吸力面的气流分离,减小了叶尖涡;叶尖小翼改变了叶尖区域的压力分布,加大了叶尖部位上下压力面的压差,提升了0.975～0.99倍叶片长度处的叶片转矩,风力机出力变大;加装后掠L型小翼后,风力机的轴向推力增加0.46%～0.81%,增幅较小,而风力机组发电效率提升约3.4%～4.2%,增幅明显。

As a wind energy capture device,the aerodynamic performance of blades determines the wind energy utilization efficiency of wind turbines.In order to effectively improve the wind energy capture capability of wind turbines under low wind speed conditions,this paper refers to the design concept of adding small wings to the wing tips to enhance aerodynamic performance,adds swept L-shaped tip winglets to the blade tips of wind turbines,and uses the standard k-εturbulence model to simulate the three-dimensional flow field of the blades with small wings and prototype blades under different wind speed conditions.The results show that,compared with the original blade,the swept L-shaped tip winglet has a diversion effect on the airflow passing through the tip region,improves the flow pattern of the tip airflow,makes the airflow passing through the tip smooth and smooth,effectively reduces the induced resistance at the tip,blocks the airflow separation at the suction surface at the tip,and reduces the tip vortices.The tip winglet changes the pressure distribution in tip region,increases the pressure difference between upper and lower pressure surfaces at blade tip,increases the blade torque at(0.975~0.99)R position,and increases the output of wind turbine.After adding the swept L-shaped tip winglet,the axial thrust of wind turbine increases by 0.46%~0.81%,with a small increase,while the efficiency of wind turbine increases by about 3.4%~4.2%.