考虑自重影响的大型风力机复合材料叶片结构力学特性分析

Analysis of Mechanical Properties of Large Wind Turbine Composite Blade Considering Weight of Blade

为探究叶片自重对叶片结构特性影响,基于NX参数化建模的二次开发,建立NREL 5 MW风力机叶片三维壳体模型,结合复合材料铺层设计,通过CFD方法获得叶片表面压力分布并加载至复合材料叶片模型,采用有限元法对其进行模态、静力及屈曲分析,得到叶片自重对其结构特性影响。结果表明:复合材料叶片抗扭转能力较强,弯曲振动是引起其疲劳破坏的主因;考虑叶片自重后,叶尖位移最多增加8.7倍,一阶屈曲因子最多降低93%,最大屈曲变形量最多减小89.47%;考虑叶片自重后,180°相位角时叶片表面应力分布最为恶劣,结构分析时应优先考虑;考虑叶片自重后,270°相位角时屈曲因子最大,180°时屈曲因子最小,分析180°相位角叶片可获更符合工程实际的临界屈曲载荷;额定风载下,135°、180°及225°相位角叶片局部屈曲域处于其最长截面前缘区,其他情况下,易在背风面尾缘镶板区出现局部屈曲,应对这些区域进行优化设计增强其抗屈曲能力;叶片自重应加以考虑。

In order to explore the effect of blade weight on blade structural characteristics,a three-dimensional shell model of NREL 5 MW wind turbine blade was established based on the secondary development of NX parametric modeling,combined with the composite material layer design.The blade surface pressure distribution was obtained by CFD method and applied to the composite blade model.This work used finite element method to carry out the analysis of modal,static and buckling from the composite blade model,which drew the influence of blade weight on structural characteristics.The results show that the composite material blade has strong to rsional resistance and bending vibration is the main cause of its fatigue failure.When weight of the blade is considered,the tip displacement of the blade increases by 8.7 times at most,the first order buckling factor decreases by 93%at most and the maximum buckling deformation decreases by 89.47%at most.When the phase angle is 180°,the blade surface stress distribution is the worst,so this phase angle should be given priority in structural analysis.The buckling factor is the largest at 270°and smallest at 180°,thus the analysis of 180°phase angle blade can be more in line with the actual engineering.In the case of considering the rated wind load,the local buckling domain of the 135°,180°and 225°phase angle blade is at the leading edge of its longest section.In other cases,local buckling is prone to appear in the trailing edge panel area of the leeward side.Therefore,the optimal design should be carried out in these areas to enhance the buckling resistance and the blade weight should be considered.