侧通风窗纵横比对连栋温室流场均匀性的影响

Influence of Aspect Ratio of Side Ventilation Window on Air Circulation in Terraced Greenhouses

【目的】探究侧通风窗纵横比对连栋温室内流场均匀性的影响,为温室设计建造提供理论依据。【方法】本研究以广州地区连栋蝶形开窗温室为研究对象,采用数值模拟和试验结合的方法,设计了4种不同开窗纵横比方案并与试验温室(即开窗方案C)进行对比,引入不均匀系数评价流场均匀性,研究不同开窗纵横比下连栋温室内流场的分布规律。【结果】通过实测值和模拟值对比,温度、风速的平均误差分别为2.48%和8.76%,均方根误差分别为1.10℃和2.1×10^(-3)m/s,验证了模型的有效性;不同开窗纵横比对连栋温室室内平均温度无显著影响,但温度不均匀系数存在明显差异,其中开窗方案A较开窗方案C总体温度不均匀系数减少了41%;5种开窗方案中,开窗方案A的总体平均风速和风速不均匀系数均优于其他开窗方式,与开窗方案C相比,平均风速提高了23%,风速不均匀系数降低了41%。【结论】从温室内流场分布角度来看,适当降低侧通风窗纵横比,能够有效降低温度、风速不均匀程度。

【Objective】The geometry of side ventilation windows is an important design parameter of greenhouse and this paper investigates the impact of their aspect ratio on air circulation in terraced greenhouses.【Method】The study is based on butterfly windows of terraced greenhouses in Guangzhou,using numerical simulation and experimental data measured from a greenhouse(Window C).We modelled five aspect ratios and compared the numerical simulations with experimental data.Air circulation in the greenhouse is quantified using non-uniformity coefficients.【Result】The average errors between the simulated and measured temperature and wind speed are 2.48%and 8.76%respectively,and their associated root mean square errors are 1.10℃and 2.1×10^(-3)m/s,respectively.Changes in the aspect ratio do not result in significant effect on average temperature in the greenhouses,but affect temperature variation noticeably.Among the five aspect ratios we compared,Window A gives the greatest average wind speed and highest wind uniformity coefficient.Compared with Window C,it increase average wind speed by23%and the wind speed uniformity coefficient by 41%.【Conclusion】Our results show that reducing the aspect ratio of the side ventilation window as currently used by local farmers can effectively increase the uniformity of both temperature and wind speed in the greenhouse.