设施塑料大棚风洞试验及风压分布规律  

The wind tunnel test of plastic greenhouse and its surface wind pressure patterns

作　　者：杨再强[1] 张波[1] 薛晓萍[2] 黄川容[1] 朱凯[1] 

机构地区：[1]南京信息工程大学江苏省农业气象重点实验室,南京210095 [2]山东省气候中心,济南250031

出　　处：《生态学报》2012年第24期7730-7737,共8页Acta Ecologica Sinica

基　　金：公益性行业(气象)科研专项(GYHY 201006028;GYHY201206024);江苏省科技支撑项目(BE2010734);江苏高校优势学科建设工程(PAPD)项目

摘　　要：风洞试验是研究建筑结构表面风压分布规律的最重要且有效的技术手段。利用NH-2型风洞研究设施塑料大棚表面风压分布规律,风洞为串置双试验段闭口回流风洞,风速连续可调,最高风速为90 m/s。试验模型的几何缩尺比为1∶6,模型表面共布置192个测点,其中端面布置3排测压点,共63个测点,模型固定在风洞转盘上,试验风向角从0°到180°,间隔15°,共13个风向角。测量和分析不同风向角下设施大棚表面的风压系数和分布规律,并推导出了设施大棚各区域发生风灾的临界风速。结果表明:设施大棚迎风面以风压力为主,迎风边缘等值线密集,风力梯度大;背风面则受风吸力影响,风力变化平缓。在不同风向角下,设施大棚各迎风区域风压系数均由正压向负压过渡,在此过程中出现了零压区;而一直背风的区域风压系数均为负值。在45°风向角下,大棚顶端迎风边缘最高点处的负压达到最大。根据公式推导出各区域的临界风速,设施大棚顶部两侧区域受风吸力影响最大,最小临界风速为14.5 m/s,研究为设施大棚的风灾防御提供科学依据。Wind tunnel testing is the most important and effective approach to study distribution patterns of wind pressure on building surfaces. In this study, we used string in a double closed silent backflow NH-2 type wind tunnel to investigate wind pressure patterns on plastic greenhouse surfaces. The wind tunnel used is 6 m long, 3 m wide and 2.5 m high. Wind speed can be continually adjusted, and maximum wind speed is 90 m/s. Nonuniformity of the flow field at the experimental site was less than 2% , turbulence intensity less than 0.14% , and average air drift angle less than 0.5. The geometrical reduced scale ratio of the experimental model is 1：6. Ceiling height, shoulder height, width, and length of this model is 0. 475 m, 0.25 m, 10 m, and 1. 155 m, respectively. The cambered surface of the ceiling is a semi-ellipse, with semi- major axis 0.5 m. There are 192 points on the model surface, of which 63 points are distributed in three rows on the front surface, and 129 points in another three rows on the ceiling surface. The three rows on the front surface are defined as A1, A2, A3. In each row, 21 points are arranged in ascending order, and the interval between two points is 47.5 m. In the A3 row, the distance between each point and the eamberod ceiling surface is 10 mm. On the ceiling surface, models were fixed on the turntable of the wind tunnel, and 13 wind direction angles with an interval of 15° were set in sequence from 0° to 180°. We measured surface wind pressure of a plastic greenhouse, analyzed its patterns, then deduced the critical wind speed of wind-related disasters for such greenhouses. Results show that surface wind pressure changed with wind direction angle. At 45° wind angle, edge wind pressure was negative and reached a maximum value when the windward surface met the leeward surface. The windward surface was controlled by wind pressure. On its windward edge, isolines were dense and the wind gradient large. In contrast, the leeward surface was controlled by wind suction; the wind therefore did

关 键 词：风洞试验 风压分布 临界风速 设施大棚 

分 类 号：S625.2[农业科学—园艺学]