基于仿生学翼型的垂直轴风机在湍流环境下的特性研究

In order to meet the power supply needs of grassland and mountainous areas, to achieve local transformation of wind energy in the urban areas, this project will study a new airfoil of vertical axis wind turbine, which has superior power performance in turbulent flow field, based on the principle of bionics. From the preliminary study, it is found that the leading-edge protuberances on hydrofoils have excellent hydrodynamic characteristics, especially with a high lift-drag ratio in the turbulence intensity conditions. Determine the formation and evolution of flow vortex in turbulent flow field is the key to master the new type of airfoil. It is important to improve the wind energy utilization of the wind turbine in the complex flow field environment and also has an important theory significance and application prospects. Firstly, this study focuses on the study of aerodynamic forces in 2D airfoil with wind tunnel experiments. In order to simulate the natural wind characteristics, active turbulence grids and boundary layer generation frame were developed by our team. After that, the effect of the leading-edge protuberances on stall phenomenon will be investigated. The flow separation and reattachment on the airfoil structure in the turbulent environment will be discussed with tuft experiment and CFD simulation technique. Moreover, the process and characteristics of the flow vortex for the new bionic airfoils in the turbulent flow will also be revealed. Finally, the flow field around the wind turbine are measured by the application of PIV technology, and the installation and control conditions, system features and energy conversion efficiency are discussed through experimental measurements. For the study of VAWT airfoil suitable for turbulence intensity wind environment, correlation analysis and design theory are proposed in this project and a relatively complete system design for straight-bladed VAWT is presented.

针对草原、山区地带供电需求及风能在城市就地转化问题，本项目将开展在湍流风况下具有良好性能的仿生翼型垂直轴风机研究。前期研究发现，仿座头鲸胸鳍设计的风机叶片具有优越的流体力学特征，特别在湍流条件下具有高升阻比的显著特点。研究仿生翼型前缘凸起在湍流环境下翼面涡流的形成和演变过程，是掌握仿生翼型的关键，对提高风机在复杂流场环境下的风能利用，具有重要理论意义。项目以风机二维翼面空气动力学和流场特性研究为基础，利用风洞模拟自然风湍流及大气边界层等关键技术，探讨波状前缘凸起结构对叶片失速性能的影响。采用tuft试验和CFD仿真技术，考察翼型凸起结构在湍流环境下，气流在翼面分离和再附着规律，揭示新型仿生翼型在湍流环境下的流向涡变化特性。应用PIV技术测量风机周围流场强度，探讨翼型安装和控制条件与垂直轴风机的匹配规律及能量转化效率。建立适用于湍流风场环境下稳定工作的仿生翼型风机设计理论和实验方法。

针对草原、山区地带供电需求及风能在城市就地转化问题，开展在湍流风况下具有良好性能的仿生翼型垂直轴风机研究。结合风洞实验和CFD数值仿真分析仿生翼型前缘凸起在湍流环境下翼面涡流的形成和演变过程，通过外场测试研究风力机在高湍流自然风况下的气动性能，分析仿生翼型凸起结构对风力机气动性能的影响规律，为优化仿生叶片提高风力机气动性能具有重要研究意义。.通过在风洞中开展风力机气动性能实验与数值仿真相结合的方法，探究了不同风况对标准叶片气动载荷和输出特性影响的敏感性和规律性。获悉了风力机叶片表面压力分布、风力机转矩、功率和翼面气流分离再附着随风速变化的规律，同时揭示了风况对叶片气动载荷变化影响的作用机理。在叶片翼展方向气流和叶尖涡的影响下，风力机叶片功率主要由叶片0.6倍叶片长度的中间段提供，在尖速比1.38、2.19和2.58时，叶尖位置的局部功率系数相对于中间截面分别下降了38.29%、46.78%和56.42%。.根据仿座头鲸胸鳍前缘凸起结构的控流机理，在标准翼型NACA0021基础上构建适用于垂直轴风力机的仿生翼型。通过CFD数值仿真研究发现使用正弦函数波状的前缘凸起仿生叶片有效减少了叶片表面气流的展向流动和抑制叶尖涡生成，并在大攻角下具有较好的流动控制效果和气动性能，通过延迟失速和促进叶片表面层流向湍流的过渡，提高了动态失速下风力机的功率性能，在1.38、2.19和2.58时，仿生叶片的功率系数分别提高了7.02%、7.35%和3.42%。通过垂直轴外场测试研究垂直轴风力机在自然风况下的气动性能，研究发现仿生叶片在低风速高湍流时，仿生叶片对垂直轴风力机气动性能的提升效果比较显著。.综上所述，通过数值仿真和风洞实验研究风力机叶片气动载荷、输出特性和尾流恢复之间的关联机理，为研究垂直轴风力机气动性能提供可靠的实验数据支撑；建立适用于垂直轴风力机设计理论和实验方法，构建仿生叶片的前缘凸起结构，搭建了垂直轴风力机的外场测试平台，对提高风力机在复杂流场环境下的风能利用率具有重要研究意义。