【作者】 周振凯；

【导师】 刘占芳；

【作者基本信息】 重庆大学 ， 工程力学， 2011， 硕士

【摘要】 面对迫在眉睫的能源和环境危机,以及风能开发成本的不断降低,各国都在进一步加大对风力发电的开发力度。风力机是风能利用的核心,而水平轴风力机是风力机主要形式。叶片作为水平轴风力机的关键部位,其外形决定了风力机风能的转换效率,因而叶片优化设计技术在风力机设计制造中占有相当重要的地位。另外,风力机运行过程中,叶片受到交变性和随机性载荷,必然会发生振动。叶片的振动特性对叶片的变形和寿命有重要影响,因此对其进行研究也是十分必要。本文对水平轴风力叶片优化设计及振动特性开展了相关研究,论文的主要工作和结论如下:①回顾了国内外水平轴风力机发展现状,考察了风力机叶片设计的研究现状,并对水平轴风力机叶片的优化设计研究现状进行了综述。②详细介绍了水平轴风力机空气动力学理论及Wilson叶片设计方法。③在片条理论基础上,考虑叶尖和轮毂损失、叶栅、失速及叶片三维效应等各种修正因素,建立了水平轴风力机气动性能计算模型。采用此模型对NREL 20kW风力机进行了气动性能计算,并对比NREL的计算结果,分析和检验了模型的正确性及实用性。④对定桨距风力机和变桨距风力机采用了两种不同的设计方法。对于定桨距风力机的叶片优化设计,本文将叶片设计攻角当着变量来处理,在不超过额定功率和基本运行风速的范围内,综合考虑叶片截面翼型气动特性,叶片截面之间的约束和风场风速的概率分布情况,以全年发电量最大为优化设计目标,建立了定桨距风力机关于叶片弦长和扭角的气动优化模型并利用遗传算法对20kW定桨距风力机叶片进行优化设计。通过对20kW定桨距3叶片风力机的气动性能评价以及与NREL的同功率风力机的对比表明,本文优化设计的风力机具有更好的气动性能。对于变桨距风力机的叶片优化设计,利用Wilson方法对叶片进行初步外形设计,然后以设计攻角为变量建立了以额定风速下功率系数最大为优化目标的1 MW变桨距风力机叶片优化模型并利用遗传算法进行了优化计算,对比Wilson方法设计的结果,本文优化的风力机具有更好的气动性能,表明本文设计方法的优越性。⑤基于叶片外形数据和翼型二维离散数据,经过复杂的矩阵坐标变换得到叶片各点的三维数据,利用三维建模软件UG进行了实体建模,为扭曲实体建模和其他复杂实体建模提供了新思路。⑥根据三维模型建立了叶片的有限元模型,利用ANSYS Workbench对叶片进行了模态分析并计算得到Campbell图。计算结果表明,叶片的主要振动形式是挥舞振动和摆振振动,叶片以额定转速运行时,不会发生共振现象。更多还原

【Abstract】 Facing imminent energy and environmental crisis, and wind development costs continue to reduce,countries were to further increase efforts to develop wind power .Wind turbine is the core of wind energy,and horizontal-axis wind turbine is the most common form of wind turbines. The blade is a key component of horizontal axis wind turbine, the shape of it decided the wind energy conversion efficiency, thus the optimal design of blade is the primary task of the wind machine design. In addition, the dynamic characteristics of the blades had an important effect on their deformation and life. Therefore, to study it is also very necessary.In this paper, the horizontal axis wind blade aerodynamic shape optimization and dynamic characteristics were researched. The main work and conclusions of the paper were as follows:①The domestic and international development status of horizontal axis wind turbine and the blade design wind turbines were stated. The blade aerodynamic optimization of horizontal axis wind turbine was reviewed.②The horizontal-axis wind turbine aerodynamic theory and Wilson method were introduced in detail.③Considering the cascade theory, tip losses, root losses, blades 3-d rotating effect, stall correction of momentum theory and other modifying factors, the aerodynamic performance calculation model was established on the basis of strip theory. NREL 20kW wind turbine aerodynamic performance was calculated according to this model, contrasting the results of NREL, which showed the model was correct and practicality.④Fixed-pitch and pitch-variable wind turbines were designed using two different methods in this paper. For fixed-pitch wind turbines blade optimization,the design attack angles was treated as a variable, considering the blade airfoil section aerodynamic characteristics, the constraints between the blade section and the wind speed probability distribution of wind farm, an optimization model with the objective of maximum annual energy production is established in the range of rated power and basic operating wind speed. The blade geometry of a 20kW fixed-pitch wind turbine was optimized using genetic algorithm according to the model. Through the evaluation of the aerodynamic performance of 20kW fixed-pitch wind turbine and the comparison with the same type wind turbine of NREL, the results showed that optimized wind turbine has a better aerodynamic performance. For pitch-variable wind turbines blade optimization, using first Wilson theory to design of blades preliminary, and then treating the design attack angles as a variable, using genetic algorithm to design again. Through the blade optimization and the aerodynamic performance evaluation of a 1.0MW pitch-variable wind turbine, the results showed that optimized wind turbine had a better aerodynamic performance, which illustrated the superiority of this design method.⑤The two-dimensional airfoil profile data points were converted into three-dimensional data points of blades through a complex matrix of coordinate transformation. And a solid modeling of blades was established by three-dimensional modeling software UG, which provided some new ideas for establishing distortion modeling and other complex solid modeling.⑥The finite element model of the blade was established through three-dimensional model, and the blade vibration modal and the Campbell diagram were analyzed by ANSYS Workbench. The results showed that the main vibration form of blade were waved and shimmy vibration, the resonance phenomenon did not occur when blades running at rated speed.更多还原