定日镜群风荷载干扰效应的数值模拟

Numerical simulation of heliostat group's wind load interference effects

定日镜通常以群的形式出现,在气流流过时,各个单体之间会出现干扰效应,影响到它们的风压分布以及流场特性。为了研究这种干扰效应,建立数值风洞模型,编制相应的UDF程序,模拟B类地貌下大气边界层风场入口条件,选用标准k-ε模型模拟计算不利工况、常用工况、停放工况下的两定日镜前后径向布置的干扰效应和四定日镜辐射状布置的干扰效应,计算风力干扰因子,给出其流场分布图,分析不同工况、不同距离、不同布置形式等因素对定日镜表面风压的影响。计算中通过选用混合网格强制内部非结构化网格向外部结构化网格过渡,使用Gambit软件中的Size Function功能,在确保网格精度的同时大大减小了计算量。研究结果表明:在径向布置定日镜中,后方定日镜处于前方定日镜的尾流区,其表面风压减小较为明显,仰角为0°时对距离影响最为敏感;辐射状布置的定日镜受到斜侧前方定日镜干扰,表面风压呈现增长趋势。

Heliostat usually appears in group.When air current passes,and there will emerge interference effect between individuals and further influences their wind pressure distribution as well as flow field features.In order to study this kind of interference effect,a numerical wind tunnel model was established,and corresponding UDF program was drafted,and entry conditions of atmospheric boundary layer’s wind field was simulated with terrain roughness of category B.Interference effects of two and four heliostats were computed by radial disposition on their disadvantageous,common and suspending operating modes using standard k-ε model simulation.The wind power interference factors were calculated,and the flow field distribution map was drafted.The impacts on heliostat surface wind pressure of factors such as different operating modes and distances,dispositions were analyzed.The mixed grid was selected to enforce the interior unstructured grids to transform to exterior structured ones.The size function in Gambit software was used to reduce calculation while the grid precision was ensured.The results show that wherein heliostats by radial disposition,the rear heliostat locates in the front heliostat’s wake area,the surface wind pressure reduction is obvious,and the operating mode of elevation angle 0o is the most sensitive to space influence.Due to the front side interference,the surface wind pressure of heliostats by radial disposition increases.