How to control the airflow inside the greenhouse with a shading net in winter
The arrival of winter has also ushered in a difficult time for greenhouse vegetables. In order to avoid and reduce the impact of greenhouse cultivation pests and diseases on the indoor airflow field, the ventilation openings of multi-span greenhouses are generally equipped with insect prevention nets.
In winter, there is a large temperature difference between the outdoor and indoor areas, but the simultaneous presence of heat and wind pressure, as well as the limitations of the greenhouse boundary, will inevitably cause turbulence. Due to the height of the multi-span greenhouse and the ventilation openings at the upper and lower parts, it is necessary to consider the frictional effect of the ground on the outdoor airflow. Taking the greenhouse near the gable as an example, due to the high-speed airflow at the gable door, the airflow is carried along the roof ridge of the greenhouse. When it reaches the leeward side near the gable wall, it is blocked by the gable wall, and the airflow movement route changes. One part flows out from the side window, and the other part forms two large horizontal circulations at the bottom of the sunshade. The static range of the circulation center is large.
In the absence of a shading net, the symmetry of the airflow pattern is poor, and the boundary between the inlet and outlet airflow of the side window is not clear. On the windward side of the side window, there is also a small amount of airflow flowing out while entering the air. The sunshade nets produced by manufacturers are widely used in winter, and the use of sunshade nets in winter also plays a significant role.