农业工程学报2019，Vol.35Issue(15)：165-174,10.DOI:10.11975/j.issn.1002-6819.2019.15.021
拱形塑料大棚风致干扰效应及风压特性研究
Wind-induced interference effects and wind pressure characteristics of arched plastic greenhouses
摘要
Abstract
Wind-induced interference effect commonly occurs among arched plastic greenhouse group. To describe such influence and finally determine the wind load shape coefficients considering the interference effects, we conducted a series of numerical simulations based on computational fluid dynamics (CFD). Combining the Reynolds-averaged N-S equations and the Realizable k-ε turbulence model, the surface wind pressure characteristics of the models for single greenhouse and greenhouse group under different wind direction angles and distances were studied separately. In combination with the actual production, 5 rows and 6 columns symmetrical layout was adopted as the greenhouse group’s model with different gap distances (2, 4, 6, 8, 10 and 12 m) and wind direction angles (0, 30, 45, 60 and 90 degrees). In order to achieve quantitative analysis of the wind-induced interference effects, the interference factor was introduced in this paper as an important contrast parameter. According to the characteristics of the greenhouse structure, the greenhouse partition was reasonably set to realize the key research of wind pressure characteristics in wind-sensitive areas. In the numerical wind tunnel simulation, unstructured grids suitable for greenhouse group’s model were used to divide the computational domain. The calculation parameters such as blocking ratio, inlet and outlet conditions, and near-wall treatments and so on were appropriately set. By comparing with wind tunnel test results of similar models, the present numerical simulations were verified. According to the simulation results, the arrangement of greenhouse group causes the wind-induced interference effects, which will change wind pressure characteristics of the greenhouses. The effects can result in amplification effects (the outer area of the greenhouse group) and the shielding effects (the middle area of the greenhouse group), among which the amplification effects threatens the safety of the structure and cannot be ignored. The interference effects is significantly affected by the wind direction angle and the gap distance, and specifically it decreases with the increase of distance, and tends to be stable when the distance between greenhouses is about 10 m. Based on the analysis of the variation law of the mean wind pressure coefficients and wind direction angles on the greenhouse group’s roofs, it is obvious that the interference effects weakens the wind pressure ventilation ability of the greenhouse group as a whole. From the point of view of advantageous to wind pressure ventilation, the suggestions on planning and layout of the greenhouse group are put forward, that is, the long axis direction of the greenhouses should be perpendicular to the dominant wind direction in summer of the area where the greenhouse group is located and the gap distance should be increased appropriately. Finally, according to the wind-induced interference effects, the wind load shape coefficients for arched plastic greenhouses (the rise-span ratio is 3:8) are given, which are convenient for design. The wind load shape coefficients of greenhouses which are located in the outer area of the greenhouse group: At 0 wind direction angle, +0.41 on the windward side, -0.78 on the middle roof, -0.26 on the leeward side and -0.48 on both sides of gables; at 90 degrees wind direction angle, +0.36 on the windward gable, -0.44 on the roof. The wind load shape coefficients of greenhouses which are located in the middle area of the greenhouse group: At 0 wind direction angle, +0.30 on the windward side, -0.71 on the middle roof, -0.26 on the leeward side and -0.48 on both sides of gables; at 90 degrees wind direction angle, +0.34 on the windward gable, -0.35 on the roof. Wind-induced interference effects exists in arched plastic greenhouses arranged in group, and wind pressure changes on the greenhouses caused by wind-induced interference effects should be considered in design.关键词
荷载/模型/通风/拱形塑料大棚/数值风洞/干扰因子/风致干扰效应/风荷载体型系数Key words
loads/model/ventilation/arched plastic greenhouses/numerical wind tunnel/interference factor/wind-induced interference effects/wind load shape coefficients分类
农业科技引用本文复制引用
吴昆,王少杰,张广鹏,魏珉,刘福胜,吕鑫..拱形塑料大棚风致干扰效应及风压特性研究[J].农业工程学报,2019,35(15):165-174,10.基金项目
国家大宗蔬菜产业技术体系项目(CARS-23-C04) （CARS-23-C04）
中国博士后科学基金面上项目(2017M622239) （2017M622239）
国家重点研发计划政府间国际科技创新合作重点专项项目(2017YFE9135300) （2017YFE9135300）
