风力机风轮低频振动特性的实验模态研究

Experimental modal analysis on low-frequency vibration characteristics of wind turbine

利用国际上先进的PULSE16.1结构振动分析系统,对4个风力机风轮进行模态测试,发现风轮在挂机状态下,低频时存在轴向窜动效应和圆盘效应两种普遍存在的振动方式。振动发生时叶根处分别伴随着往复式和回转式剪切应力,影响到风力机的安全稳定运行和寿命。同时,利用挂机实验对比证明了通常采取的风轮通过夹具安装后在平面上进行模态实验的方法,对风轮振动特性的完整和准确获得均存在一定的影响。初探性分析,轴向窜动效应的产生因主要与塔架的弹性有关;圆盘效应的产生因主要与风轮的安装方式有关。相关研究成果有可能为很多风力机叶片在远短于设计寿命期频繁发生疲劳损伤事故的分析提供新的思路和理论支撑。

Two widespread vibration modes of the wind wheel in operating condition,namely,the axial moving mode and the disk mode were investigated by using the PULSE16.1 system in modal experiments of four wind turbines.The reciprocating stress and rotary stress at the blade roots while the vibration is generated will affect the stable operation and the life of wind turbine.For testing vibration characteristics,the wind wheel test under hook state testifies that great deviation will be introduced by using the conventional experimental method in which the wind wheel is installed through the fixture and is in-plane tested.The preliminary analysis shows that the generation of the axial moving mode is mainly due to the elasticity of the tower and the generation of the disc mode is mainly due to the installation manner of the wind wheel.The fact of existense of these two vibration modes may provide some new idea and theoretical support to explain fatigue damage accidents of many wind turbine blades whose life is much shorter than the design one.