摘要
风力机的尾流效应对下游风力机的气动性能和疲劳载荷均有重要影响。为了研究叶尖速比对水平轴风力机非定常尾迹特性的影响,该研究在中性大气条件下采用基于致动线模型的大涡模拟(Large Eddy Simulation, LES)方法对不同叶尖速比下运行的风力机进行了数值模拟,并采用本征正交分解(Proper Orthogonal Decomposition, POD)方法对风力机尾迹结构进行了分析。结果表明,叶尖速比对风力机下游12D(D为风轮直径)范围内速度分布有显著影响,随着流向距离的增加,叶尖速比的影响逐渐减弱;风轮尾迹中2D处的速度亏损最大,在下游28.5D附近速度完全恢复;叶尖速比对风力机尾迹湍流强度有很大影响,叶尖速比为2时尾流湍流强度最弱,而叶尖速比为3时尾流湍流强度最大,说明该叶尖速比下尾流与大气边界层掺混作用剧烈,有利于尾迹速度恢复;叶尖速比对风力机尾迹结构的尺度和含能大小有显著影响,叶尖速比为3时尾迹中的大尺度结构及其含能占比最高,随着POD模态阶数的增加,尾流结构尺度和含能逐渐减小;风力机尾迹结构由反向旋转的高、低速涡对组成,其垂向尺度可达到整个边界层厚度,而风力机风能吸收利用效率主要体现在尾迹展向湍涡结构的尺度。该研究可为深入理解叶尖速比对风力机尾迹平均统计特征及结构演化的影响提供依据,为风力机优化设计和运行策略制定提供帮助。
Wind turbine wakes have posed a great challenge to the aerodynamic performance and fatigue loads of the downstream wind turbines.This study aims to explore the impacts of blade tip speed ratio on the unsteady wake characteristics of horizontal wind turbines under neutral atmospheric stable conditions.Large Eddy Simulation(LES) with the actuator line model was adopted to investigate the flow field around the wind turbine under the different ratios of tip speed.A snapshot of proper orthogonal decomposition was selected to distinguish the coherent structures in the wind turbine wakes wind turbines.Results show that the tip speed ratio presented a remarkable influence on the velocity profile of the wind turbine wakes within the downstream distance range of 12 times of wind turbine diameter.More importantly,the influence was relatively weakened with the increase of the distance downstream.Furthermore,the velocity deficits reached the maximum at the downstream distance of around two times of wind turbine diameter,which recovered completely around the downstream distance of 28.5times of wind turbine diameter for all tip speed ratios.As such,the tip speed ratio posed notable impacts on the turbulence intensity of wind turbine wakes.There was the weakest turbulence intensity,when the tip speed ratio was 2,while the maximum,when the tip speed ratio was 3,indicating the strongest momentum and energy exchange.Correspondingly,the tip speed ratio of 3 was greatly beneficial to the wake recovery during the operation of the wind turbine.Meanwhile,there was also a significant influence of tip speed ratio on the scale and energy contained in coherent structures in the wind turbine wakes.The wind turbine model demonstrated that the largest turbulence structures and the highest energy were achieved in the wind turbine at the tip speed ratio of 3.The coherent structures were composed of high-and low-speed alternately counter-rotating vortices in the wind turbine wake,the scale of which in the vertical direction reached the boundary l
作者
王燕
程杰
贾安
王亮
胡锐锋
Wang Yan;Cheng Jie;Jia An;Wang Liang;Hu Ruifeng(School of Energy&Power Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Center for Particle-Laden Turbulence,College of Civil Engineering and Mechanics,Lanzhou University,Lanzhou 730000,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2022年第7期69-77,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金(11902131)
甘肃省自然科学基金项目(20JR5RA443)。
关键词
风力机
发电
数值模拟
叶尖速比
尾迹特性
本征正交分解
wind turbine
power generation
numerical simulation
tip speed ratio
wake characteristics
proper orthogonal decomposition
