基于CFD模型的大跨度温室自然通风热环境模拟

doi:10.3969/j.issn.1000-6362.2017.04.003

摘要/Abstract

摘要： 大跨度温室作为一种新型南北走向的钢骨架覆膜温室，解决了传统日光温室土地利用率低、空间狭小的问题。为了研究在自然通风条件下大跨度温室的温度和气流场的分布规律，以及不同室外风速条件下通风口开度对大跨度温室温度和气流场的影响，利用计算流体力学（computational fluid dynamics, CFD）软件构建三维稳态大跨度温室模型，模拟自然通风条件下大跨度温室内的温度场和气流场，并采集典型晴天下通风口开启50%时大跨度温室内13个测点的温度，将各测点的测量值与模拟值进行比较，最后利用已验证模型模拟分析通风口开度（25%、50%、75%、100%）在不同室外风速（1、2、3、4 m·s-1）条件下的大跨度温室温度和气流场。验证结果表明：模型模拟值与实测值的绝对误差在0.2～2.8℃，均方根误差为1.6℃，最大相对误差为9.9%，平均相对误差为4.1%，表明模拟值与实测值吻合良好。模拟结果显示，温室顶部温度高，底部温度低；室外冷空气从西侧通风口进入，温室内西侧温度低于东侧；温室内平均风速从南到北逐渐减小；温室中部风速明显小于东西两侧。大跨度温室上通风口及侧通风口全开时，温室内温度分布较均匀。温室通风口开度一定时，温室内通风率与室外风速呈显著线性正相关。考虑温室内温度及风速对作物的影响，以降温为主要目的时，建议通风口开度取75%～100%，若室外风速大于3m·s-1且室内温度能满足作物生长，则建议通风口开度＜75%。

关键词: CFD模型, 模型, 温度场, 气流场, 通风率

Abstract: To solve the problem that the inner available space of the traditional Chinese solar greenhouse is usually small, a new-type large-scale greenhouse which was tunnel type and had a wide span with steel frame and south-north orientation was designed. The?distribution?of airflow and temperature patterns, the effect of vent openings under different outdoor wind speed conditions on airflow and temperature patterns in a naturally ventilated large-scale greenhouse were studied. Firstly, simulation model of the airflow and temperature patterns in a naturally ventilated large-scale greenhouse was established by means of three-dimensional computational fluid dynamics (CFD). Secondly, the model was validated via the comparison with the field experimental results at the same locations where 13 temperature sensors were installed under the typical sunny day when the vent opening degree was 50%. The comparison between simulations and measurements showed that the absolute error was within 2.8℃, the square error was within 1.6℃, the maximum relative error was less than 9.9% and the average relative error was around 4.1%. An agreement existed between simulated and experimental results. Finally, the model which was validated was used to study the effect of vent opening degree (25%, 50%, 75% and 100%) under different outdoor wind speed (1, 2, 3, 4m·s-1) conditions on airflow and temperature patterns. The results showed that, the average temperature of the top of the greenhouse was higher than the bottom of the greenhouse, and the colder air outside went into the greenhouse from the west side vent, so the average temperature of the west of the greenhouse was lower than the east of the greenhouse. From south to north, the average airflow rates decreased in the greenhouse. Because of the west and east vents, the average air velocity in the center of greenhouse was lower than the side. When both top and side vents full opened, the airflow in greenhouse was relatively low. Temperature distribution was uniform in the large-scale greenhouse when the vent opening degree was 100%. The outdoor wind speed had a significant positive correlation with the ventilation rate when vent opening degree was kept constant. For the purpose of cooling, the optimum vent opening degree was 75%-100%. If the temperature of the greenhouse was suitable for crop growth and the outdoor wind speed was faster than about 3m·s-1, the optimum vent opening degree should be less than 75%.

Key words: CFD model, Model, Temperature field, Air flow field, Ventilation rate

张芳，方慧，杨其长，程瑞锋，张义，柯行林，卢威，刘焕. 基于CFD模型的大跨度温室自然通风热环境模拟[J]. 中国农业气象, 2017, 38(04): 221-229.

ZHANG Fang, FANG Hui, YANG Qi-chang, CHENG Rui-feng, ZHANG Yi, KE Xing-lin, LU Wei, LIU Huan. Ventilation Simulation in a Large-scale Greenhouse Based on CFD[J]. Chinese Journal of Agrometeorology, 2017, 38(04): 221-229.

参考文献

[1]孟力力,杨其长,王柟,等.日光温室热环境模拟模型的构建[J].农业工程学报,2009,25(1):164-170. Meng L L,Yang Q C,Wang N,et al.Visual simulation model for thermal environment in Chinese solar greenhouse[J]. Transactions of the CSAE,2009,25(1):164-170.(in Chinese) [2]魏琴芳,马骥.对日光温室发展中土地利用率的探讨[J].农业工程技术·温室园艺,2006,(8):22-23 Wei Q F,Ma J.The discussion of land utilization in the development of solar greenhouse[J].Agriculture Engineering Technology Greenhouse Horticulture),2006,(8):22-23.(in Chinese) [3]周升,张义,程瑞锋,等.大跨度主动蓄能型温室温湿环境监测及节能保温性能评价[J].农业工程学报,2016,32(6):218- 225. Zhou S,Zhang Y,Cheng R F,et al.Evaluation on heat preservation effects in micro-environment of large-scale greenhouse with active heat storage system[J].Transactions of the CSAE, 2016,32(6): 18-225.(in Chinese) [4]Fatnassi H,Boulard T,Bouirden L.Simulation of climatic conditions in full-scale greenhouse fitted with insect-proof screens[J].Agricultural & Forest Meteorology,2003,118(1-2): 97-111. [5]Katsoulas N,Bartzanas T,Boulard T,et al.Effect of vent openings and insect screens on greenhouse ventilation[J]. Biosystems Engineering,2006,93(4):427-436. [6]Wang S X,Wang X.Ventilation rate of various vents in plastic covered multi-span greenhouse[J].Transactions of the Chinese Society of Agricultural Engineering,2009,25(11): 248-252. [7]Fatnassi H,Boulard T,Bouirden L.Development,validation and use of a dynamic model for simulate the climate conditions in a large scale greenhouse equipped with insect-proof nets[J]. computers & Electronics in Agriculture,2013,98(7): 54-61. [8]方慧,杨其长,张义,等.日光温室热压风压耦合自然通风流量模拟[J].中国农业气象,2016,37(5):531-537. Fang H,Yang Q C,Zhang Y,et al.Simulation on ventilation flux of solar greenhouse based on the coupling between stack and wind effects[J].Chinese Journal of Agrometeorology, 2016,37(5):531-537.(in Chinese) [9]Okushima L,Sase S,Nara M.A support system for natural ventilation design of greenhouses based on computational aerodynamics[J].Acta Horticulturae,1989,248:129-136. [10]Kacira M,Short T,Stowell R.A CFD evaluation of naturally ventilated mulei-span sawtoothgreenhous[J].Transactions of the ASAE,1998,41(3):833-836. [11]Sase S,Okushima L,Kacira M.Optimization of vent configuration by evaluating greenhouse and plant canopy ventilation rates under wind-induced ventilation[J]. Transactions of the ASAE,2004,47(6):2059-2067. [12]Mistriotis A,Arcidiacono C,Picuno P,et al.Computational analysis of ventilation in greenhouses at zero and low wind speeds[J].Agricultural & Forest Meteorology,1997,88(1-4): 121-135. [13]Fatnassi H,Boulard T,Poncet C,et al.Optimisation of greenhouse insect screening with computational fluid dynamics[J].Biosystems Engineering,2006,93(3):301-312. [14]Khaoua S A O,Bournet P E,Migeon C,et al.Analysis of greenhouse ventilation efficiency based on computational fluid dynamics[J].Biosystems Engineering,2006,95(1):83- 98. [15]Jiang G,Hu Y,Liu Y,et al.Analysis on insulation performance of sunken solar greenhouse based on CFD[J].Transactions of the Chinese Society of Agricultural Engineering,2011,27(7): 275-281. [16]程秀花,毛罕平,倪军.风速对温室内气流分布影响的CFD模拟及预测[J].农机化研究,2010,32(12):15-18. Cheng X H,Mao H P,Ni J.CFD simulations and predicts for effect of external airflow speeds on airflow profiles inside venlo glasshouse[J].Journal of Agricultural Mechanization Research,2010,32(12):15-18.(in Chinese) [17]程秀花,毛罕平,伍德林,等.栽有番茄的玻璃温室内气流场分布CFD数值模拟[J].江苏大学学报(自然科学版),2010, 31(5):510-514. Cheng X H,Mao H P,Wu D L,et al.CFD simulations of airflow distributions inside glasshouse with tomato crops[J]. Journal of Jiangsu University,2010,31(5):510-514. (in Chinese) [18]程秀花,毛罕平,倪军,等.温室环境-作物湿热系统CFD模型构建与预测[J].农业机械学报,2011,42(2):173-179. Cheng X H,Mao H P,Ni J,et al.Numerical prediction and CFD modeling of relative humidity and temperature for greenhouse-crops system[J].Transactions of the Chinese Society for Agricultural Machinery,2011,42(2):173-179.(in Chinese) [19]张起勋,于海业,张忠元,等.利用CFD模型研究日光温室内的空气流动[J].农业工程学报,2012,28(16):166-171. Zhang Q X,Yu H Y,Zhang Z Y,et al.Airflow simulation in solar greenhouse using CFD model[J].Transactions of the CSAE,2012,28(16):166-171.(in Chinese) [20]周伟,汪小旵,李永博.可变边界条件下的Venlo温室温度场三维非稳态模拟[J].农业机械学报,2014,45(11):304-310. Zhou W,Wang X H,Li Y B,et al.Unsteady temperature simulation under variable boundary conditions for venlo type greenhouse[J].Transactions of the Chinese Society for Agricultural Machinery,2014,45(11):304-310.(in Chinese) [21]李永欣,李保明,李真,等.Venlo型温室夏季自然通风降温的CFD数值模拟[J].中国农业大学学报,2004,9(6):44-48. Li Y X,Li B M,Li Z,et al.CFD simulation of a naturally ventilating cooling process for a venlo greenhouse in summer[J].Journal of China Agricultural University,2004, 9(6):44-48.(in Chinese) [22]程秀花.温室环境因子时空分布CFD模型构建及预测分析研究[D].镇江:江苏大学,2011. Cheng X H.Predication and CFD modeling for greenhouse microclimates temporospatial distributions[D].Zhenjiang: Jiangsu University,2011.(in Chinese) [23]陈教料,胥芳,张立彬,等.基于CFD技术的玻璃温室加热环境数值模拟[J].农业机械学报,2008,39(8):114-118. Chen J L,Xu F,Zhang L B,et al.CFD-based simulation of the temperature distribution in glass greenhouse with forced-air heater[J].Transactions of the Chinese Society for Agricultural Machinery,2008,39(8):114-118.(in Chinese) [24]任守纲,杨薇,王浩云,等.基于CFD的温室气温时空变化预测模型及通风调控措施[J].农业工程学报,2015,31(13): 207-214. Ren S G,Yang W,Wang H Y,et al.Prediction model on temporal and spatial variation of air temperature in greenhouse and ventilation control measures based on CFD[J].Transactions of the CSAE,2015,31(13):207-214.(in Chinese) [25]方慧,杨其长,张义,等.基于CFD技术的日光温室自然通风热环境模拟[J].中国农业气象,2015,36(2):155-160. Fang H,Yang Q C,Zhang Y,et al.Simulation performance of a ventilated greenhouse based on CFD technology[J]. Chinese Journal of Agrometeorology,2015,36(2):155-160.(in Chinese) [26]Chintakovid W,Kozai T.Growth of tomato (lycopersicone- sculentum, Mill.) plug transplants in a closed system at relatively high air current speeds:a preliminary study[M]. Springer Netherlands,2000. [27]Kacira M,Sase S,Okushima L.Effects of side vents and span numbers on wind-induced natural ventilation of a gothic multi-span greenhouse[J].Japan Agricultural Research Quarterly,2004,38(4):227-233.