全风向来流非高斯风场风机疲劳寿命可靠性分析

在Hermite矩模型基础上,根据Kaimal谱生成某典型风机结构正常风速条件下,三种不同概率特性风场(高斯、非高斯硬化和软化),在考虑来流风向和平均风速联合概率密度条件下,以塔架基础连接处为例,对风机进行疲劳寿命可靠性分析.由叶片的气动模型和多体动力,计算出风机的动力响应,并对响应的时域和频域特性进行分析.基于线性损伤累积理论和Paris公式,对来流全风向条件下的裂纹形成寿命和裂纹扩展寿命进行了详细讨论.结果表明,裂纹形成寿命对风荷载的非高斯性较为敏感,而裂纹扩展寿命对风荷载的非高斯性并不敏感,需要考虑风荷载的非高斯性对风机结构疲劳损伤的影响.此外,在考虑全风向来流条件下,疲劳裂纹形成和扩展阶段的失效位置相同,均在主导风向上.

Reliability analysis of the fatigue life of wind turbines under a non-Gaussian wind field with a full-direction inflow

Using the Hermite moment model, three types of wind fields with different probability characteristics, namely the Gaussian, hardening non-Gaussian, and softening non-Gaussian processes, were generated via the Kaimal spectrum for a typical wind turbine under operational conditions. Reliability analysis of the fatigue life of the wind turbine was performed by taking tower base con-nections as an example with consideration of the joint probability density distribution of the wind direction and mean wind speed. The dynamic response was calculated by an aerodynamic model of the blade and multi-body dynamics, and the time-and frequency-domain characteristics of the response were analyzed. Using linear damage accumulation theory and the Paris equation, the fatigue crack initia-tion life and crack growth life of the turbine were discussed in detail. Fatigue estimation shows that the crack initiation life of the tur-bine is more sensitive to non-Gaussian winds, whereas its crack propagation life is less sensitive to the non-Gaussian characteristics of wind load. The influence of the non-Gaussian characteristics of wind load on the fatigue damage of the wind turbine should be consid-ered. In terms of the full-direction inflow, the failure positions of the crack initiation and propagation stages are identical and in the dominant wind direction.