大型风力机复合材料叶片动态特性及气弹稳定性分析

Dynamic analysis and aeroelastic stability analysis of large composite wind turbine blades

采用参数化建模技术快速建立大型风力机复合材料叶片三维有限元壳模型,并在此基础上对叶片的固有动力学特性进行停机及以额定转速旋转两种工况下的模态分析,其中旋转工况考虑了离心力导致的应力刚化效应和旋转软化效应。通过编制插值程序,将CFD计算所得的叶片表面分布压力,导算到叶片结构计算的有限元壳模型上,并以此为载荷对叶片进行静气弹稳定性分析。以某初步设计的1.5MW风机为例的计算结果表明:在参数化三维壳模型建模基础上进行的模态分析技术与结合CFD的静气弹稳定性分析技术,有利于快速、准确地计算大型复合材料叶片的动态特性、识别叶片结构的薄弱部位,并预测叶片发生局部屈曲的可能性及其发生的位置。

Parametric modeling technique is developed to fast build the three-dimensional finite element shell model of a preliminarily designed large composite wind turbine blade,which is subsequently used in the dynamic analysis and static elastic aeroelastic stability analysis of the blade.In the dynamic analysis,natural frequencies and corresponding modal shapes are obtained for the blade in the case of being still as well as being rotating with rated revolution.For the rotating blade,the stress stiffening effect and spin-softening effect due to the centrifugal forces are taken into account.The static elastic aeroelastic stability analysis,i.e.buckling analysis in this paper,is distinct from its counterparts in adopting the pressure distributions obtained from CFD（Computational Fluid Dynamics） calculations as the loads.An interpolation code is developed to address the mismatch between the unstructured CFD grids of the blade surface and the finite shell elements used in the buckling analysis,allowing mapping the pressures computed by using CFD to the finite element model.It is concluded that structural analysis of large composite wind turbine blades using three-dimensional finite element shell model is beneficial to revealing the relatively weak zones of the blades.