MW级风力机叶片气动特性及流固耦合特性研究

发布时间：2018-03-02 09:15

本文关键词： 叶片设计翼型数值模拟气动性能流固耦合　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着世界性能源危机日益加剧，环境污染日趋严重，推进新能源和可再生能源的开发利用已是大势所趋。风能具有就地可取、分布广、无污染、可再生等优点，已成为新能源发展的重要方向。风力发电有着广阔的发展前景，在世界各地得到迅速发展。风力发电对于调整能源结构、降低环境污染、缓解能源危机等方面有着非常重要的意义。叶片是风力机的关键零部件，叶片的翼型、结构形式直接影响风力机的性能。叶片设计是一个复杂的多目标优化过程。理想的叶片不仅能获得良好的气动性能和较高的能量转换效率，还能使风电机组的整体性能得到改善。因此本文结合吉林省科技厅科技发展计划项目“基于HPC的兆瓦级风力机系统动力学仿真模拟研究（201205095）”，选取风力机的功率为2MW，对其展开气动结构设计与性能研究。主要研究内容和结论有以下几点。 1.采用动量叶素理论设计法对风力机叶片参数进行计算，并应用粒子群算法对参数进行优化。优化后的风力机有较好的启动性能，弦长和扭角更加合理，年发电量增加了5.97%。利用空间坐标转化法，将各截面翼型坐标转化为空间三维坐标，建立风力机叶片的空间三维模型，为叶片气动特性分析奠定基础。 2.翼型的气动特性对风力机整机的性能具有决定性的影响。对优化后叶片所选用的典型翼型NACA4415进行数值模拟，得到该翼型在额定风速下的气动特性。此外，还研究了雷诺数、相对弯度和相对厚度等因素对翼型气动性能的影响。 3.采用周期性边界条件，利用Fluent软件对单叶片三维流场数值仿真，得到叶片迎风面、背风面的压力分布和r/R=0.2、0.5、0.7三个截面下的空气流速及湍流动能分布图。分析了迎风面和背风面压力形成机理。研究了空气流速与湍流动能沿叶片展向的分布规律。研究结果表明空气流速和湍流动能随r/R的增大而增大。空气流经过叶片后没有明显分离和漩涡，表明叶片周围气流比较稳定。湍流动能强度围绕翼型由叶根到叶尖处不断增大，这是叶尖处容易失速的原因。以上结论表明，本文所设计的叶片有较好的气动特性。 4.采用流固耦合方法研究了风力机整机模型的气动特性以及动力学特性。先用CFX软件计算整机模型气动特性，再将气动特性载荷加载到固体风力机上，实现单向流固耦合。主要分析额定风速下叶片振动频率、振型以及形变，研究叶片变形与载荷分布相互影响机理。对风力机模型无预应力状态下静力学特性也进行了分析。计算结果表明所设计的风力机在流固耦合作用下不容易发生共振，，验证了设计的合理性。
[Abstract]:As the world energy crisis intensifies and environmental pollution becomes more and more serious, it is a general trend to promote the development and utilization of new and renewable energy sources. Wind energy has the advantages of local desirability, wide distribution, no pollution, renewable and so on. Wind power has become an important direction in the development of new energy. Wind power has a broad development prospect and has been developed rapidly all over the world. Wind power generation can adjust the energy structure and reduce environmental pollution. It is of great significance to alleviate the energy crisis and so on. The blade is the key component of the wind turbine, the airfoil of the blade, The structural form directly affects the performance of the wind turbine. The blade design is a complex multi-objective optimization process. The ideal blade can not only obtain good aerodynamic performance and high energy conversion efficiency. It can also improve the overall performance of wind turbine. Therefore, this paper chooses the power of wind turbine to be 2MWs according to the project of Science and Technology Development Plan of Jilin Province Department of Science and Technology, "dynamic Simulation Research of MW Wind Turbine system based on HPC (201205095)". The main research contents and conclusions are as follows. 1. The blade parameters of the wind turbine are calculated by the momentum leaf element theory design method, and the parameters are optimized by the particle swarm optimization algorithm. The optimized wind turbine has better start-up performance, more reasonable chord length and torsion angle. By using the method of space coordinate transformation, the airfoil coordinates of each section are transformed into three dimensional spatial coordinates, and the spatial 3D model of the blade of the wind turbine is established, which lays a foundation for the analysis of the aerodynamic characteristics of the blade. 2. The aerodynamic characteristics of the airfoil have a decisive effect on the performance of the wind turbine. The aerodynamic characteristics of the airfoil under rated wind speed are obtained by numerical simulation of the typical airfoil NACA4415 selected by the optimized blade. In addition, the Reynolds number is also studied. Effects of relative curvature and relative thickness on aerodynamic performance of airfoil. 3. Using periodic boundary condition and Fluent software to simulate the three-dimensional flow field of a single blade, the upwind surface of the blade is obtained. The pressure distribution on the leeward surface and the distribution of air velocity and turbulent kinetic energy on the three sections of r / R ~ (2 +) 0. 2 / 0. 5 ~ 0. 7. The formation mechanism of the pressure on the upwind and leeward surfaces is analyzed. The distribution of the air velocity and turbulent kinetic energy along the blade direction is studied. The results show that the air velocity and turbulent kinetic energy increase with the increase of r / R. It shows that the airflow around the blade is relatively stable, and the turbulent kinetic energy intensity is increasing from the root to the tip of the airfoil, which is the reason for the easy stall at the tip of the blade. The above results show that the blade designed in this paper has better aerodynamic characteristics. 4. The aerodynamic and dynamic characteristics of the wind turbine model are studied by using the fluid-solid coupling method. The aerodynamic characteristics of the model are calculated by CFX software, and the aerodynamic characteristic load is loaded into the solid wind turbine. Unidirectional fluid-solid coupling is realized. The vibration frequency, vibration mode and deformation of blade under rated wind speed are analyzed. The interaction mechanism between blade deformation and load distribution is studied. The static characteristics of the wind turbine model without prestress are also analyzed. The calculated results show that the designed wind turbine is not prone to resonance under fluid-solid coupling. The rationality of the design is verified.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM315

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