连栋塑料温室自然通风流场的稳态模拟——顶窗配置形式对温室内流场的影响

Steady simulation of airflow distribution of natural ventilation inside multi-span plastic greenhouse:effect of transom window configuration on airflow field inside greenhouse

比较华东地区连栋塑料温室3种典型的不同顶窗配置形式对其自然通风效果的影响,以Navier-Stokes方程为模型基础,运用流体动力学分析软件CFX对配置不同顶窗的温室内自然通风气流场进行了三维稳态模拟,外界风向平行于温室屋脊的方向.模拟结果表明:顶窗配置形式对温室内自然通风影响较大,室内流场差异明显,平均流速最大相差30%以上,但气流最大速度相差不大.当连栋温室配置小屋脊顶窗时,在两侧栋内存在漩涡中心静止区域,但数量少,面积小,气流运动整体相对均衡且剧烈,通风效果最好;半拱顶窗其次;谷间顶窗相对较差.顶窗通风量占整个温室通风的比例较大,从顶窗进入的气流遍及几乎整个温室上部和大部分下部空间,气流运动在顶窗开向侧比较集中,但总体运动比较均匀.

Based on the Navier-Stokes equation and with computational fluid dynamic （CFD） software CFX, 3D numerical steady simulation of natural ventilation was performed in the multi-span plastic greenhouse, and the effect of transom window types on the airflow was analyzed. The outside wind direction was assumed to be parallel to the greenhouse ridge. The results showed that transom window types have much influence on airflow field inside the greenhouse, and that airflow distribution differs distinctively. The average velocity varies about 30%, while the maximum velocity does not vary much in three window types. In the case of small ridge opening, there are some stagnant fields in the whirlpool centre of two side-spans, while the number of whirlpool and stagnant occupied area are little, and the overall airflow is even and strong and shows good ventilation effect. The small vault opening is in the next place, and the small gutter opening is the worst. Airflow from the transom window takes a big share in overall greenhouse ventilation, and it extends to most area, especially the upper part and most of the down part of the greenhouse. More airflow concentrates around lean-to transom window areas, while the overall airflow is comparatively even.