基于CFD的水平轴风力机叶尖小翼增功研究

CFD-BASED POWER ENHANCEMENT OF WINGLETS FOR HORIZONTAL-AXIS WIND TURBINES

基于风力机叶片增功装置设计要求,以NREL 5 MW叶片为设计原型,以扭角、上反角及后掠角3种小翼外形参数为优化因素设计正交试验表,每种因素分别选取4个水平值,采用计算流体力学(CFD)方法对加装16种不同构型小翼的叶片进行数值模拟。计算结果表明,叶片整体可增功约1.466%,同时推力增加约1.570%;影响扭矩的最主要因素为扭角,影响推力的最主要因素为上反角;通过分析叶片近尾迹流场发现,优化的叶尖小翼布局可改变叶片叶尖涡强度分布,调整叶尖翼型截面气动力特性,进而改善叶片气动性能。

For the power enhancement of horizontal-axis wind turbine blades,the NREL 5 MW blade with 16 winglet profiles were used in numerical simulation of computational fluid dynamics(CFD). The geometrical parameters in consideration include twist angle,dihedral angle and sweep angle. In order to reduce the overall computational costs,orthogonal tables were established for the parameters above with four per each. Current results showed that,with the optimal configuration the maximum power increases approximately by1.466% and the thrust increases by 1.57%. It is found that twist angle plays the most important role in the torque of wind turbine and so is dihedral angle to thrust. We also analyzed the wake flow behind the blade disk. It is shown that the optimal winglet layout produces a re-distribution of the tip vortex structure of blades and then the improvement of the aerodynamic performance of wind turbine blade is expectable.