大型风力机非线性动力学及其优化设计理论研究

The traditional dynamics analysis method for wind turbines was established on the aerodynamics model which is based on the blade element - momentum theory and the structural dynamics model which is based on small deflection assumption. But modern wind turbines are designed with increasingly large-scale structure and high flexibility, during operation, the flexible components undergoes considerable deflection and vibration, which make the traditional method no longer capable for the analysis of the complicated non-linear dynamics of modern large-scale wind turbines. In this project, based on the achieved research results in wind turbine aerodynamics and structural dynamics, it is proposed to study the non-linear aerodynamic characteristics of the flexible blade during vibration and deflection through theoretical study, wind tunnel test and CFD analysis, and to study the structure dynamic response characteristics of the turbine using non-linear beam theory and multi-body system theory when considering the structural non-linearity of flexible components, and then to implement the dynamics analysis method which considers fluid structure interaction for the whole wind turbine structure. Based on this, the multidisciplinary optimization theory and methodology, which systematically take into account the aerodynamic performance, transient load characteristics, structure topology characteristics, structural strength and fatigue characteristics, would be presented for the modern large-scale wind turbine blade design. The research of this project can not only form the theoretical base of the dynamics analysis and structure optimization, but also support the independent design of new generation large scale wind turbines, which has great theoretical significance and values engineering application.

传统的风力机动力学分析方法建立在基于叶素-动量理论的空气动力学模型与基于小变形假设的结构动力学模型之上。现代风力机向着大型化和柔性化的方向发展，其柔性部件工作时发生大尺度的变形和振动，传统分析方法已不能胜任此时产生的复杂非线性动力学效应的分析。申请项目拟利用在风力机空气动力学与结构动力学方面取得的前期研究成果，结合理论分析、风洞试验与CFD 方法，研究柔性叶片在振动和变形时的非线性气动特性，采用非线性梁理论与多体系统理论，研究考虑柔性部件结构非线性时的机组结构动力响应特性，并实现考虑气动与结构相互作用的流固耦合动力学分析方法。在此基础上，建立综合考虑气动性能、动态载荷特性、结构拓扑特性、结构强度和疲劳特性，适应风力机大型化发展趋势的叶片多学科优化设计理论与方法。项目的成功实施，可以为新一代大型风力机的动力学分析与自主设计提供理论基础与设计指导，具有重要的理论意义与应用价值。

项目针对大型风力机在运行过程中叶片和塔架会产生较大变形和振动的特点，考虑传统风力机动力学分析方法建立在叶素-动量理论的空气动力学模型与基于小变形假设的结构动力学模型之上的缺点，研究了机组柔性部件的变形和振动引起的空气动力的变化以及对于机组部件生命周期疲劳载荷的影响，在此基础上实现了风力机的整机载荷计算模型。基于整机载荷分析模型，结合叶片的结构特性分析及强度分析有限元模型，实现了叶片的多学科优化设计模型，用于在满足气动性能和结构强度的要求下，设计出更轻质的叶片以降低成本。.项目首次探索了柔性叶片的变形对于叶片气动阻尼的影响，研究结果对于开发大型风力机动力学分析程序和整机稳定性分析具有一定的指导意义和参考价值。首次探索了翼型在复合运动下的动态气动特性，并以此为基础提出了对于叶素动量理论的修正；首次比较了不考虑叶片振动速度和考虑叶片振动速度下的叶片生命周期疲劳载荷的计算差异，研究结果对于叶片的安全设计具有较重要的意义。项目实现了两种塔架气动阻尼的计算方法，并首次比较了两种塔架气动阻尼计算方法对于塔架生命周期疲劳载荷计算的影响,研究结果对于指导塔架的安全设计也具有较重要的意义。.项目提出了对于Beddoes-Leishman动态失速模型的修正方法，对于风力机翼型，修正方法可以获得更好的计算结果，这有助于开发更精确的气动计算程序。项目探索了综合考虑气动和结构的叶片优化设计方法并实现了优化设计程序。采用该方法可以在保证气动性能和结构强度的要求下，实现质量的降低。这对于实现叶片更优化的设计制造具有较重要的参考价值。