由于温室效应的加剧以及能源需求的不断增加，风电机组装机容量在过去二十年里取得了飞速增长。虽然垂直轴风电机组受叶片攻角周期性大幅度变化的影响，气动效率显著低于水平轴风电机组，但它具有无需对风、噪音小、重心低、占地省等优势，显现出良好的应用发展潜力。然而，垂直轴风电机组具有显著的流场非定常特性，实验和仿真难度较高，基础性研究工作的积累还有较多欠缺，这些问题很大程度上限制了垂直轴风电机组的研究与应用。本文从单风电机组气动特性、多风电机组通用实验平台设计、多风电机组协同效应实验以及风电机组尾流与功率相关性分析等方面入手，开展了与风电机组气动效率有关的协同效应的研究。首先，通过单风电机组风洞实验，研究了入流风速、叶尖速比和桨距角等工作参数对风电机组气动特性的影响规律。在测试风速范围内，风电机组的功率系数-叶尖速比特性基本不变，叶片的最佳桨距角在8°附近；通过变桨可以有效调节风电机组的输出功率，进一步提出了一种新型变桨机构的概念设计。其次，在单风电机组气动特性研究基础上，设计完成了多风电机组通用实验平台。该平台结构紧凑、简洁可靠，能支持多风电机组转子尺寸和风电机组位置的灵活调整，实现了多路伺服电机的运动控制和数据信号的实时采集，同时能够兼容多风电机组协同效应与流场特性的实验研究。多风电机组协同效应实验发现了叶尖速比、相对位置以及旋转方向等参数对风电机组功率的影响关系。当两台风电机组横向放置且反向向前旋转时，平均功率系数最大提高了8.2%；位于单风电机组和双风电机组下游的风电机组的功率系数最高分别增加了45.2%和61.1%；通过调整上游双风电机组的旋转方向，可以使下游风电机组的功率产生21.5%的变化。最后，为了揭示垂直轴多风电机组协同效应的机理，利用粒子图像测速系统研究了风电机组在不同旋转方向和排布方式下尾流中速度分量的变化特征，基于ANSYS Fluent软件进一步研究了速度分布对下游风电机组叶片气动特性的影响。结果表明，转子赤道面内流向速度的大小约为横向速度的7倍，流向速度的加速现象导致了协同效应的产生，协同效应的效果同时受流向速度的大小与分布影响。结合二维的流场特性实验以及气动特性仿真，可以对风电机组协同效应的效果进行有效的解释和准确的预测。讨论了协同效应对多风电机组单元功率密度的影响，通过优化横向间距，多风电机组单元的功率密度相较于单风电机组提高了56%。
The scale of wind power generation has grown rapidly over the past two decades as a result of the intensification of the greenhouse effect and the gradual increase in global energy demand. Although the aerodynamic efficiency of vertical axis wind turbine is significantly lower than that of horizontal axis wind turbine due to the periodic and large change of blade Angle of Attack, it has the advantages of omnidirectional blades, low noise, low center of gravity and low land occupation, showing good application and development potential. However, the flow field of vertical axis wind turbine shows significant unsteady characteristics, the related experiments and simulation are difficult, and the accumulation of basic research work is still lacking. These problems limit the research and application of vertical axis wind turbine to a great extent. In this paper, the synergistic interactions related to the aerodynamic efficiency of wind turbines are studied from the aspects of single wind turbine aerodynamic characteristics, multi-wind turbine general experimental platform, ulti-wind turbine synergistic effects experiment, and the correlation analysis between wake characteristics and power performance of wind turbines.Firstly, the effects of inlet wind speed, tip speed ratio and pitch angle on the aerodynamic characteristics of single wind turbine were studied by wind tunnel experiments. Within the tested wind speed range, the power coeffcient to tip speed ratio characteristics of the wind turbine are basically unchanged, and the optimal pitch angle of the blade is around 8°. The output power of wind turbine can be effectively regulated by changing the pitch angle, and a new new concept design of variable pitch mechanism was proposed.Secondly, a general experimental platform for multiple wind turbines was designed and completed on the basis of the research on the aerodynamic characteristics of a single wind turbine. The platform is compact, simple and reliable, and can support the flexible adjustment of different rotor sizes and positions of wind turbines, realize the motion control of multi-channel motor and real-time data signal collection, and is compatible with the experimental study of multi-wind turbine synergistic effect and flow field characteristics. The effects of blade tip speed ratio, relative position and rotation direction on power performance of wind turbines were found in the multi-wind turbine synergitic experiment. When the two wind turbines were placed laterally and rotated forward, the maximum average power coefficient increased by 8.2%. Wind turbines located downstream of single wind turbines and dual wind turbines have the highest power coefficient increase of 45.2% and 61.1%, respectively. By adjusting the rotation direction of the upstream dual wind turbine, the power output of the downstream wind turbine can be changed by 21.5%.In order to reveal the mechanism of synergistic interaction, the variation characteristics of velocity component in the wake of wind turbine under different rotation directions and arrangement modes are studied by using particle image velocimetry system. The influence of velocity distribution on the aerodynamic characteristics of downstream wind turbine blades is further studied based on ANSYS Fluent software. The results show that the streamwise velocity in the equatorial plane of the rotor is about 7 times of the cross-stream velocity. The acceleration of the streamwise velocity leads to the synergistic interaction between vertical axis wind turbines, which is affected by the magnitude and distribution of the streamwise velocity at the same time. By combining two-dimensional flow field characteristic experiment and aerodynamic characteristic simulation, the effect of synergistic interaction can be effectively explained and accurately predicted. Finally, the influence of synergistic interaction on the power density of multi wind turbine units is discussed. By optimizing the transverse spacing, the power density of multi wind turbine units is 56% higher than that of single wind turbine units.
