湿热环境下复合材料风力机叶片气弹稳定性

AEROELASTIC STABILITY OF COMPOSITE WIND TURBINE BLADE UNDER HYDROTHERMAL ENVIRONMENT

对湿热环境下复合材料风力机叶片气弹稳定性进行了分析.将细长叶片简化为Euler-Bernoulli型悬臂梁,基于复合材料梁理论,在本构方程中引入湿热效应,使用Hamilton原理,建立了湿热环境下复合材料叶片弯扭(挥舞-扭转)耦合动力学方程,进而得到叶片线性自由振动特征方程,使用假设模态法求解振动特性,讨论了截面扭角、湿热效应、铺层角等因素对叶片气弹稳定性的影响,得到如下结论:(1)扭转阻尼比非常小,易出现气弹不稳定,增加截面扭角可改善气弹稳定性;(2)当出现气弹不稳定时,温度的升高会加剧气弹不稳定;(3)湿度对气弹稳定性影响较小;(4)纤维铺层角对气弹性稳定性影响显著.

The aeroelastic stability of the composite wind turbine blade under hydrothermal environment is investigated in this paper. An Euler-Bernoulli beam model is used to describe slender blade. Hydrothermal effect is introduced through constitutive equation based on composite beam theory. The governing equation of the coupled bending-torsion（ flap-feather） vibration for the composite blade under hydrothermal environment is then established based on the generalized Hamiltonian principle. The characteristic equation of the blade linear free vibration is obtained from the governing equation,and the assumed-modes method is used to calculate vibration characteristics. Furthermore,the effects of twist angle of section,hydrothermal effect and ply angle on blade aeroelastic stability are discussed. The following conclusions are drawn：（ 1） torsion motion is prone to aeroelastic instability since the damping ratio of torsion is very small,but the aeroelastic stability can be improved by increasing twist angle of section;（ 2） the increasing of temperature aggravates the instability when aeroelastic instability occurs;（ 3） the influence of moisture concentration on aeroelastic stability is very little;（ 4） the effect of ply angle on aeroelastic stability is large.