单一水平轴风电机组尾迹的模拟方法与流动机理研究综述
REVIEW OF RESEARCH ON THE SIMULATION METHOD AND FLOW MECHANISM OF A SINGLE HORIZONTAL-AXIS WIND TURBINE WAKE
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摘要: 为实现碳达峰、碳中和“3060”目标, 风能将在我国能源体系发挥重要作用. 风力机尾迹是影响风电性能和度电成本的关键因素, 需在风力机布置和控制设计中充分考虑. 本文首先介绍风力机尾迹的数值模拟方法, 包括解析模型、低阶模型、大涡模拟和来流湍流生成方法. 解析模型和低阶模型可快速计算风力机尾迹, 但依赖于模型参数, 且不能或不能准确预测尾迹湍流特性. 结合风力机参数化模型的大涡模拟可准确预测尾迹蜿蜒等湍流特征, 是流动机理研究的有力工具, 可为发展快速预测模型提供数据和理论支撑. 接着, 本文介绍了叶尖涡、中心涡和尾迹蜿蜒并讨论其产生机理. 对于湍流来流, 叶尖涡主要存在于近尾迹. 蜿蜒是远尾迹的主要特征, 影响下游风力机的来流特征. 尾迹蜿蜒的产生有两种机制: 来流大尺度涡和剪切层失稳. 数值和观测结果显示两种机制共同存在. 机舱和中心涡对尾迹蜿蜒有重要影响. 采用叶片和机舱的致动面模型可准确预测尾迹蜿蜒. 研究显示不同风力机尾迹间的湍流特征存在相似性, 为发展尾迹湍流的快速预测模型提供了理论依据. 当前研究多关注平坦地形上的风力机尾迹, 复杂地形和海洋环境下的大气湍流和风力机尾迹的机理复杂, 现有工程模型无法准确预测, 有待深入研究.Abstract: In order to achieve the "3060" target of carbon peak and carbon neutrality, wind power will play an important role in our nation's energy system. The wake of a wind turbine is a key factor that affects the performance and levelized cost of wind power. It needs to be fully considered in the layout and control design of the wind turbine. This article first introduces the computational methods of wind turbine wakes, including analytical models, low-order models, large-eddy simulation, and methods for generating inflow turbulence. Analytical models and low-order models can compute wind turbine wakes fast, but they rely on model parameters and cannot or cannot accurately predict the turbulence characteristics of wind turbine wakes. Large-eddy simulation with parameterized models for wind turbines can accurately predict turbulence characteristics such as wake meandering. It is a powerful tool for investigating wake mechanism and can provide data and theoretical support for development of fast prediction models. Next, the article introduces the tip vortices, hub vortex and wake meandering and discusses their mechanism. For turbulent inflows, tip vortices mainly exist in the near wake. Meandering is the main feature of the far wake, which affects the characteristics of inflow for downstream wind turbines. There are two mechanisms for wake meandering: large-scale eddies of the incoming flow and shear layer instability. Numerical and observation results show that the two mechanisms coexist. The nacelle and the hub vortex have an important influence on wake meandering. Using the actuation surface model of the blade and the nacelle can accurately predict wake meandering. Research has shown that the turbulence characteristics for different designs of wind turbines are similar, which provides a theoretical basis for the development of a fast prediction model for wake turbulence. Current research efforts have been focused on wind turbine wakes on flat terrain. The mechanism of the atmospheric turbulence and wind turbine wake in complex terrain and marine environments are complex, which cannot be accurately predicted using the existing engineering models and needs further in-depth research.