大气稳定性对风力机尾流影响的大涡模拟研究

Research on influence of atmospheric stability on wind turbine wakes with large eddy simulation

为研究大气稳定性对风力机尾流速度分布和结构演化的影响,通过大涡模拟方法研究了不同大气稳定性下单台风力机的流场特性,采用本征正交分解方法对流场结构进行了分析.研究结果表明:大气稳定性对风力机尾迹平均统计特性和瞬时摆振均有显著影响,对流、中性和稳定大气条件下风力机的平均尾迹长度分别在7D,8D和16D左右(D为风轮直径);对流条件下尾迹蜿蜒程度最强,尾迹中心偏移量最大,且偏移程度随尾流长度的增加而增大;对流条件下风力机下游5D处尾迹瞬时的偏移量可达27.80%,而中性和稳定条件下分别为18.75%和8.75%;大气稳定性对风电场大尺度结构也有显著影响,对流和中性条件下来流相干结构的尺度分别为稳定大气下的5倍和1.67倍,且近尾迹区漩涡含能也明显高于稳定大气条件.

To study the effect of atmospheric stability on the velocity distribution and structure evolution of wind turbine wake,the flow field characteristics of a single wind turbine under different atmospheric stability was numerically studied through large eddy simulation method,and the structure of the flow field was analyzed by proper orthogonal decomposition method.Research results show that the average statistical characteristics and the instantaneous fluctuations of the wind turbine wake are significantly influenced by the atmospheric stability,and the average length of the turbine wake are approximately 7D,8D,and 16D(where D is the diameter of wind turbine)under convective,neutral and stable atmospheric conditions,respectively.The wake meanders most strongly under convective conditions with the center of the wake deflecting most,and this deflection increases with the length of wind turbine wake.The instantaneous offset of the wake at 5D downstream of the wind turbine can be up to 27.80%under convective conditions,while it is 18.75%and 8.75%under neutral and stable conditions,respectively.The atmospheric stability also has significant influence on the large-scale structures of the wind farm,and the scale of the turbulence coherent structure of the inflow under convective and neutral atmospheric conditions are 5 and 1.67 times of that under stable atmosphere,and the energy contained in the eddies of the near wake is also significantly higher than that under stable conditions.