风力机叶片大挠度挥舞振动特性分析

FLAPWISE CHARACTERISTICS OF A WIND TURBINE BLADE WITH LARGE DEFLECTION

分析了风力机叶片大挠度挥舞振动特性.基于Hamilton原理,建立了叶片大挠度挥舞振动控制方程,其中非稳态气动力由Greenberg公式得出.使用瑞利-利兹法求解振动特征问题,得到振动的频率和无阻尼模态函数.基于得出的模态函数,使用Galerkin方法将控制偏微分方程离散,得到模态坐标方程.将振动位移分解为静态位移和动态位移,得到了静态位移和动态位移方程,考查了入流速度比对静态位移和气动阻尼的影响,并对大挠度挥舞振动动态响应进行了分析,得到如下结论:大挠度挥舞振动静态位移沿叶片展向随入流速度比的增大而增大,叶尖处位移最大;当入流速度比较小时,振动为小振幅的周期运动,入流速度比较大时,振动为大振幅的拟周期运动.

The characteristics of flap vibration of a wind turbine blade with large deflection were studied. The governing equation of the vibration under unsteady aerodynamic loads, whose expressions were derived from the Greenberg expressions, was established by applying the Hamihonian principle. The Rayleigh-Ritz method was used to calculate frequencies and mode functions. Based on these mode functions, the partial differential equation governing the vibration was discreted by using the Galerkin＇ s method. The displacement was resolved to static displacement and dynamic displacement, and the equations of the static and dynamic displacement were ob- tained. The effects of the inflow ration to the static displacement and the aerodynamic damping were discussed. The dynamic response was analyzed by using the nonlinear-dynamical tools. The results show： 1 ） that the static displacement rises with the inflow ratio, and it reaches the limit at the blade tip; 2） that the vibration is a har-monic motion for small inflow ratio, and it becomes a quasi-harmonic motion when the inflow ratio is big.