叶片挥舞振动后风轮流场特性

Characteristics of wind turbine flow field after blade vibration

为了研究水平轴风力机叶片挥舞振动后风轮尾迹流场特性的变化规律,以某NACA翼型风轮为研究对象,通过自定义UDF代码及采用动网格技术成功控制了叶片振型,使得风轮在三维旋转的同时做垂直于旋转面的挥舞运动.数值模拟中利用Fluent计算平台对风轮尾迹速度场、涡量场及压力脉动特性进行研究.研究结果显示:施加振动后风轮在1个旋转周期内均会在叶中附近产生相对速度增益区、叶尖处会产生速度亏损区域,从而使叶片受力更加不均匀,出现较大压差,加速叶片的损坏与断裂;施加挥舞振动后叶尖处涡量强度增加,叶尖涡的脱落有所延迟;施加振动前后压力脉动均呈现周期性波动,且在径向0.5 m处压力脉动波动最为明显.通过引入新的非定常因素,揭示挥舞振动对风轮尾迹流场特性影响规律,使数值模拟结果更加逼近风力机实际运行状态,对风力机叶片设计具有指导意义.

In order to study the changes in the characteristics of the flow field of the wind turbine wake after the blades of a horizontal-axis wind turbine were shaken,a NACA airfoil wind turbine was used as the research object,and the blade mode was successfully controlled by using a custom UDF code and dynamic mesh technology,so that the wind wheel performed a waving motion perpendicular to the rotation surface while rotating in three dimensions.In the numerical simulation,the Fluent calculation platform was used to study the velocity field,vorticity field and pressure pulsation characteristics of the wind turbine wake.The research results show that after a vibration is applied,the wind wheel will ge-nerate a relative speed gain region near the middle of the leaf and a speed loss region at the tip of the leaf,which will make the blade force more uneven and the pressure difference larger,resulting in the acceleration of damage and fracture of the blades.The intensity of vorticity at the blade tip increases after the application of waving vibration,and the shedding of the blade tip vortex is delayed;the pressure pulsations show periodic fluctuations before and after the vibration applied,and at the radial 0.5 m the pressure fluctuation is most obvious.By introducing new unsteady factors,the influence of waving vibration on the characteristics of the wind turbine wake flow field is revealed,which makes the numerical simulation results closer to the actual operating state of the wind turbine,and provides gui-dance for wind turbine blade design.