机械通风条件下连栋温室速度场和温度场的CFD数值模拟

Simulation of mechanical ventilation for Huabei-type multispan plastic greenhouse

为了了解温室内部气流和热量传递过程 ,设计合理的通风设施 ,建立了无植物条件下湿帘机械通风的华北型连栋塑料温室三维数值模拟模型 ,并使用CFX计算流体力学软件进行了数值模拟计算。得到了合理的速度场分布和温度场分布数值模拟结果 ,并与试验值进行了对比。与试验值相比 ,模拟结果误差≤ 5 % ,在入口风速≤ 1 5m·s-1,入口气温≤ 2 6℃ (热浮力的影响较小 )的情况下效果更好。讨论了入口风速和湿帘高度对温室可控距离的影响 :提高入口风速可以增大温室的可控距离 ,湿帘高度越大 ,可控距离越大。湿帘高度在 1 2～ 1 2 5m之间时 ,相同湿帘高度下 ,纵向距离为 5 0m的温室 ,其可控距离略小于 4 0m的温室 ;当湿帘高度超过 1 2 5m时 ,纵向距离为 5 0m的温室可控距离大于 4 0m的温室。

Mass and heat transfer in the mechanically ventilated Huabei-type multispan plastic greenhouse without plants was numerically simulated using commercial software CFD and CFX to make the airflow and heat transfer clear in the greenhouse and design ventilation equipment rationally. The prediction gives rational velocity and temperature distributions, which have been compared with the measured values of velocity and temperature. The error between the measured and the predicted value is less than 5%. It is better at the conduction of inlet air velocity less than 1.5*!m·s -1 and inlet air temperature less than 26*!℃. Finally, it is also discussed that the effect of the inlet air velocity and the height of cooling pad on the controllable distance of the studied greenhouses. The controllable distance increase when the inlet air velocity increased. The higher the height of cooling pad, the lager the controllable distance. The controllable distance of the 50*!m greenhouse is less than that of the 40*!m's when the height of cooling pad is between 1.2 to 1.25*!m, and is lager than that of the 40*!m's when the height of cooling pad exceed 1.25*!m.