百米级大柔性风电叶片非线性气弹响应分析

Nonlinear aeroelastic response analysis of 100-meter-scale flexible wind turbine blades

随着风电叶片迈入百米量级,叶片尺寸和柔性持续增大,几何非线性对叶片结构动态响应的影响更加明显。为解决大柔性叶片的非线性气动弹性计算问题,采用基于Legendre谱有限元的几何精确梁理论,耦合叶素动量理论,建立了大尺寸风电叶片气动弹性分析方法,通过带有预弯的悬臂梁算例验证了几何精确梁模型的准确性。最后,以NREL5 MW和IEA 15 MW风力机为例,分别采用线性模态叠加法和非线性几何精确梁方法计算了61.5 m叶片和117 m叶片在全工况稳态风和湍流风条件下的动态响应。结果表明,从5 MW到15 MW风力机叶片,由于几何非线性效应引起的叶尖挥舞位移和叶根挥舞弯矩数值偏差分别增加21.35%和21.23%,叶片一阶摆振模态频率也存在3.2%的偏差。百米级叶片非线性效应对叶片动态响应、摆振模态等气动弹性特性影响较大,应充分考虑非线性气动弹性对叶片设计的影响,以保障风力机的运行安全性。

As wind turbine blades reach the 100-meter-scale,the blade size and flexibility keep increasing,which makes the geometric nonlinear effect on the structural dynamic response of the blade more severe.In order to solve the problem of nonlinear aero-elastic calculation of highly flexible blades,an aeroelastic analysis method for highly flexible blades has been established by coupling the Legendre spectral finite element based geometrically exact beam theory and the blade element momentum theory.The calculation result of a curved beam agrees well with the analytical solution,validating the prediction accuracy of the geometrically exact beam theory.By taking the NREL 5 MW and IEA 15 MW wind turbines as examples,the linear and nonlinear dynamic response of a 61.5 m blade and a 117 m blade under both steady-state and turbulent wind conditions are calculated.The results show that,for the 5 MW and 15 MW wind turbines,due to the negligence of the nonlinear effect,the numerical differences of the flapwise tip deflection and the flapwise root moment are increased by 21.35%and 21.23%,respectively,and there is also a 3.2%difference in the frequency of the first edgewise mode.The nonlinear effect of the 100-meter-scale blades has a great impact on the aeroelastic characteristics such as the blade dynamic response and the edgewise mode,thus it should be fully considered in the blade design to ensure the operational safety of wind turbines.