现代化大棚通风及作物蒸腾的研究

通过三维计算流体动力学模拟确定了我国华中地区使用的扇形截面现代化塑料大棚的通风参数,并进一步预测了大棚作物的蒸腾率,考虑了作物物理形态的分形特征,提出了一种简单快速并且普适的计算温室通风率和作物蒸腾率的方法.模拟结果和试验数据的比较分析显示模型能够有效描述通风特征,给出通风参数并预测作物蒸腾率,模拟结果在正午前后最为准确.由于计算简单快捷,可用于在个人计算机上实现大棚通风根据外界环境变量的自动化调控.结果还显示相对于国外所使用温室,我国扇形截面现代化塑料大棚能够保持较好的通风和室内风向的一致性.研究结果证明了该方法的有效性、合理性和可实现性,对温室微气象智能调控的发展具有一定的参考价值.

Determination of ventilation and crop transpiration in modern polyhouse

In this article the wind pressure coefficient and discharge coefficient of a typical polyhouse(with a sector shape vertical cross-section) widely employed in central and southern China are determined through 3D computational fluid dynamics simulation.Combining the popular ventilation formula and a fractal permeability model which models crop as a porous medium with fractal characteristics.Our model provides an easy,quick,yet accurate method in calculating ventilation rate and crop transpiration.The computational results with this model are compared with measured experimental data,it is shown that this model effectively gives ventilation characteristics,coefficients and transpiration rate under steady-state hypothesis.The best corresponding result comes in noon.The calculating process is time-economical and simple in favor of robotizing using PC.It is also found this Chinese polyhouse provides good ventilation and constant indoor airflow direction.This study shows the above model effective,reasonable and its simulation realizable and valuable for future robotized regulation system of a polyhouse.