中国典型地形风能资源的湍流特征分析

STUDY ON TURBULENCE CHARACTERISTICS OF WIND ENERGY RESOURCES IN CHINA’S TYPICAL TERRAIN

选取4种风能开发利用的典型地形,对其大气边界层风场特别是湍流场的特征进行分析。通过分析不同下垫面无量纲方差与无量纲稳定度参数z/L的关系,表明均在风力机标准的湍流模型适用范围内。湍流动能随风速呈指数增长,不同稳定度下指数差异明显。湍流动能的垂直变化,除受稳定度影响外,还与下垫面有关。东海塘沿海局地平坦地形和锡林浩特平坦草原下垫面,湍流动能随高度变化较小;鄱阳湖湖陆交界复杂下垫面,近地面湍流动能明显增大,随着高度的增加,湍流动能迅速下降;河北尚义起伏的中山丘陵下垫面,地形使下层湍流动能随高度减小,上层湍流动能随高度增大。摩擦速度廓线与湍流动能廓线基本一致,但其最大值并不一定在地表附近。

In this paper,four typical terrains for wind energy utilization are selected to analyze the wind field characteristics in the atmospheric boundary layer,especially for turbulent fields.By analyzing the relationship between dimensionless variance and dimensionless stability parameter z/L for different underlying surfaces,it is shown that they are within the applicable range of the turbulence model in IEC.The turbulent kinetic energy increases exponentially with wind speed,and the exponential difference is obvious under different stability levels.In addition to the influence of stability,the vertical change in turbulent kinetic energy is also related to the underlying surface.Over the local flat surface of the Donghaitang coast and the flat grassland area of Xilinhot,the turbulent kinetic energy decreases less with height.Over the complex terrain of the lake-land interface of Poyang Lake,the kinetic energy of turbulence near the surface increases significantly,and it decreases rapidly with height.Over the undulating middle mountain hills,the terrain reduces the turbulent kinetic energy of the lower layer,and the upper layer increases with height.The friction velocity profile is basically consistent with the turbulent kinetic energy profile,but its maximum is not necessarily near the surface.