屋顶槽式聚光镜的抗风性能研究

Trough solar collector is the highest efficiency solar system. Its application is very extensive. But due to the special working performance and the use area of the trough solar collector, in the area where the land is tense or the surrounding buildings are more numerous, there are a lot of engineering cases in which the trough solar collector is installed on the roof of the building. Because of the large area of the mirror, the deformation of the mirror will cause the energy loss of the system，even the damage, so the wind load is the most important control load of the structure design. The wind field conditions of trough solar collectors installed on the roof is completely different from the near surface wind field conditions, and the wind pressure distribution and wind-induced response is certainly completely different. The project will adopt a combination of field measurement, wind tunnel test, numerical simulation and theoretical analysis to research wind field characteristics and spatial correlation of roof, the rules and characteristics of wind pressure distribution, the shape coefficient of each wind direction, and overall wind coefficient conditions, the wind-induced response analysis and the equivalent wind load. And then put forward a simplified calculation method of wind-induced response and a method to determine the equivalent wind load. Furthermore, this project will study on the influence of bearings of trough solar collector on the roof structure of the building. These conclusions could provide a theoretical basis and technical support for the wind resistant design of roof trough solar collector. The research work of this project can also provide a theoretical basis for the wind resistance research of other structures or facilities installed on the roof.

槽式聚光镜是目前国际上效率最高的太阳能聚光系统，应用非常广泛，但由于其特殊工作性能及占地面积等，在用地紧张或建筑密集区域，将槽式聚光镜安装在建筑屋顶的工程案例已非常多。槽式聚光镜迎风面积大，镜面变形会造成系统能效损失，甚至破坏，故风荷载是其结构设计最重要的控制荷载。安装在屋顶的槽式聚光镜所处风场完全不同于近地面风场，故其风压分布及风致响应也完全不同。本项目拟采用现场实测、风洞试验、数值模拟及理论分析等方法，对屋顶风场特性及空间相关性规律、不同工况下聚光镜风压分布规律、各风向角下的体型系数、整体风力系数、风致响应以及等效风荷载开展系统研究，进而提出风致响应的简化计算方法及等效风荷载确定方法，并研究槽式聚光镜支座对建筑屋面结构的影响等，为屋顶槽式聚光镜的抗风设计提供充分的理论依据和技术支撑。本项目对屋顶风场的研究工作还能为安装在屋顶上的其他结构或设施的抗风研究提供理论依据。

目前将槽式聚光镜等太阳能设备放置在屋顶的实例越来越多，但屋顶风场与近地面风场不同，因此屋顶槽式聚光镜上的风荷载效应也会有所不同。本项目采用现场实测、风洞试验、数值模拟及理论分析等方法对屋顶风场及屋顶槽式聚光镜的风荷载效应进行了系统研究。首先在张家口某处建立了现场实测基地，通过现场实测方法对某多层建筑屋顶风场特性进行了分析研究，获得了多层建筑屋顶不同水平位置和高度的平均风速与风向角、湍流强度、阵风因子、湍流积分尺度及脉动风速功率谱等风特性参数的变化规律、特征及参数间的关系等，通过风洞试验和数值模拟方法进一步分析了多层建筑屋顶风场在不同风向角下的变化规律、特征及形成机理等，并将屋顶风场与地面风场进行对比，获得了两种风场的区别。然后对屋顶槽式聚光镜模型分别进行了风洞测压试验和测力试验，获得了典型工况下屋顶聚光镜的平均风压分布、脉动风压分布、最大平均风压系数、风压系数及六个方向的风力（力矩）系数随风向角及仰角的变化规律和特征，并给出了聚光镜的最不利工况和对应的风力系数值，与地面上同尺寸聚光镜镜面进行了比较分析，获得了两者的异同。在此基础上，通过ANSYS对屋顶槽式聚光镜的风致响应进行了分析，获得了典型工况下聚光镜的位移峰值响应、风振系数、支座内力等，并给出了屋顶槽式聚光镜在最不利工况下的等效风荷载的计算方法。最后采用ANSYS建立安装槽式聚光镜前后的两种框架结构有限元模型，通过对顶层结构构件位移及内力的分析，获得了风荷载作用下聚光镜对建筑顶层结构的影响，并提出了几种相应措施。研究成果可为屋顶槽式聚光镜及其他屋顶式设备的抗风设计提供理论依据和技术支撑。