结构动态响应影响风轮气动噪声的研究

The main indicators of wind turbine performance transformed from single aerodynamic performance to high aerodynamic performance and low noise. The aerodynamic noise of the blade is the main noise source of modern wind turbines. Therefore, the design, manufacturing and operation units are eager to develop aerodynamic Noise design and analysis method. Dimension of freedom was preferred; Location of respond was positioning; Mode shape feature vectors solutions of the discrete system were calculated by means of linear system structure dynamics theory. Different types of wind wheel vibration and order of modal vibration mode were solved and analyzed to find the type and combination and achieve the general expression of structural dynamic response. During calculation process which Custom function controlled vibration of rotor pass parameters of between structure field and sound field were found and they were analyzed that structural dynamic response effected on wind turbine aerodynamic noise source distribution and aerodynamic noise radiation. The project divides the different sound source area in the calculation of aerodynamic noise, and at the same time a new unsteady factor is selected to identify the dynamic aerodynamic sound source in order to make the research on the performance of the wind turbine more realistic. It lays the foundation for the research on the aerodynamics and aero acoustics of the wind turbine Theoretical basis. The discrete data of structural vibration mode eigenvectors were Space-time continuous functional. The characteristics of transmission parameters between structure field and acoustic field were analyzed to provide a new method for the research of acoustic fluid-solid coupling analysis.

风力机叶片性能的主要指标从单一的气动性能转化为高气动性能、低噪音，而叶片气动噪声是现代风力机的主要噪声源，因此设计制造及运维单位迫切希望开发兼顾流固耦合的气动噪声设计分析方法。基于线性系统结构动力学理论，通过优选自由度的维度，确定响应拾取位置，获得风轮离散系统的振型特征向量解。解析风轮结构不同振动型式、阶次的模态振型，寻找空间连续函数的类型及其组合，获得风轮结构动态响应的一般表达式，并通过自定义函数在计算中控制其振动过程，选定结构场与声场间的传递参数，对比分析结构动态响应对风轮气动噪声源分布的影响及气动噪声辐射的影响。本项目在计算气动噪声时将声源面分区，同时选引入新的非定常因素，识别动态气动声源，使风力机性能的研究更接近实际，为风力机空气动力学及气动声学的研究奠定理论基础。同时，将结构振型特征向量离散数据时空连续函数化，分析结构场与声场间传递参数的特点，为声流固耦合分析方法研究提供新思路。

常规风力机性能分析中针对风力机进行刚体假设和经验修正，最终计算结果与实际产品性能之间有一定误差。基于此，项目组提出在风力机空气动力学性能分析中不仅考 虑风轮的旋转效应，同时兼顾结构动态特性的影响，为风力机空气动力学性能的研究 引入新的非定常因素，使风力机性能的研究更接近实际。 .通过模态试获得了风轮叶片的振动状态控制方程，结合动网格技术在运转风轮的数值 模拟中实现了对风轮的振动状态的控制，体现施加振动后在旋转周期内均会在叶中附 近产生相对速度增益区、叶尖处会产生速度亏损区域，从而使叶片受力更加不均匀， 出现较大压差，加速叶片的损坏与断裂。施加挥舞振动后叶尖处涡量强度增加，叶尖涡的脱落有所延迟。输出特性体现在弯振的施加使风轮功率下降，且下降趋势随着风速和尖速比增大而增强。发出噪声的影响想体现在叶片 0.71R 处出现轴向速度亏损,且在叶尖位置亏损最大风轮叶尖部位的最大声能量位置不随流场的流动状态而发生改变，研究成果对于叶片的优化设计和降噪方法的改进提供了可行的解决思路。.基于叶素动量理论、加速势流理论改进和优化了常规风力机性能分析中的刚体假设，修正了平衡尾流模型，建立了考虑诱导速度延迟、附加质量力、风剪切、偏航效应的新型动态尾流模型与通用、准确的动态气动数值计算模型，为预测风力机非定常载荷、极限载荷及疲劳寿命提供了新思路。