风向变化对风力机动态叶片气动载荷影响分析

Wind turbine blades are the most critical load bearing and consumable parts. Aerodynamic load is one of the most important loads on the dynamic blades. Due to the randomness and alternativeness of this load, the destructive effect caused by this load on blades or even the wind wheel is the most. People were familiar with the loads on the stationary blades and the aerodynamic response on single yaw, but the study on the effect of wind direction change speed on aerodynamic response on rotating blades is just at a shallow level. This project combines experiments and computation, and rotating telemetry, multi-channel synchronous acquisition technology were used. The speed of varying wind directions and blades rotation are the two characteristic elements. Response characteristics of flow characteristics, aerodynamic performance and aerodynamic load in motion horizontal axis wind turbines at varying wind directions have been analyzed. The physical and mathematical models have been established. The main load, influence rule about each load and the coupling and superposition results have been obtained by the variable separation approach. The airfoil and blade shape with optimized aerodynamic performance and load distribution has been sought. The main reason for the destruction of the wind turbine has been revealed and the key regulative mechanism for the blade dynamic load on different loads has been obtained. This will not only provide direct experimental evidence for analysis and judgment of the blade fatigue damage and the bad spot prediction, but also provide new ideas for aero elastic analyses and calculation on large wind turbine.

叶片是风力机最为关键的承载部件及易损部件。在叶片承受的各种载荷中，气动载荷是最重要的载荷，它具有随机性、交变性，对叶片乃至整体风轮的破坏作用最大。过去，人们对静叶片载荷和单一偏航气动响应比较熟悉，对运动状态下叶片受到风向变化快慢时气动方面响没有引起足够的重视。本项目通过旋转遥测、多通道同步采集等技术再结合风洞中搭建的风向变化试验台，以实验为主、计算为辅，重点分析风向变化快慢对运动状态水平轴风力机的流场特性、气动性能、气动载荷的响应特征；采用变量分离法得到各个作用载荷的主要影响因素、影响规律和相互耦合叠加的结果，建立相应的物理和数学模型；寻求气动性能和载荷分布较佳的翼型和叶片形状；揭示破坏风力机的主要原因，获得其在不同载荷条件下对叶片动态载荷的一些关键性的调控机理。为分析和判断疲劳损伤、预测损坏部位提供直接、重要的实验依据，也可为大型风力机气弹分析和计算提供新思路。

风力机叶片承受的各种载荷中，气动载荷是最重要的载荷，它具有随机性、交变性，对叶片乃至整体风轮的破坏作用最大。过去，人们对静叶片载荷和单一偏航气动响应比较熟悉，对运动状态下叶片受到风向变化快慢时气动方面响没有引起足够的重视。本项目通过旋转遥测、多通道同步采集等技术再结合风洞中搭建的风向变化试验台，多台高性能计算站的动网格计算，重点研究分析风向变化快慢对运动状态水平轴风力机的流场特性、气动性能、气动载荷的响应特征，数值模拟和实验吻合很好；采用变量分离法得到各个作用载荷的主要影响因素、影响规律和相互耦合叠加的结果，建立相应的合适的、精度较高的物理和数学模型；揭示破坏风力机的主要原因和机理，获得其在不同载荷条件下对叶片动态载荷的一些关键性的调控措施与机理。. 建立了风向动态变化风力机性能实验台，提出了提出风向角变化量的Lorentz分布规律和马尔可夫链模型来构建自然风风向变化的状态转移概率矩阵模型；找到影响气动性能和应力特性的主要因素、影响程度、部位和内在关系；发现影响叶片应力关键载荷以及各个载荷影响因素和相互耦合作用机理；初步掌握气动性能和应力特征分布合理的协同优化控制方法及调控策略；推出了三参数Weibull分布的风功率密度计算新公式；提出了三参数Weibull分布函数的参数特征也可作为风资源评价标准；开展了动态入流条件下风力机运行控制的数值模拟及尾流和相邻风电场之间的性能干扰，风力机引入比例积分变桨距控制和转矩控制，实现对动态入流的追踪，模拟得到的功率曲线与风力机实际功率曲线整体上吻合良好。提取、归纳风速、风向变化规律，为自然风、控制动态偏航风力机气动力学、结构动力学、噪声等特性实验奠定了前期理论准备。