Aerodynamic analysis of several insect-proof screens used in greenhouses

Abstract

Insect-proof screens constitute a physical means of protecting crops and their use has become widespread in recent years. There is no doubt as to their efficiency in controlling insects, but they do have a negative influence on greenhouse ventilation as they obstruct air-flow. It is therefore necessary not only to evaluate their efficiency as a means of protecting crops, but also to estimate the degree to which they obstruct airflow. To this end the present work analyses the aerodynamic characteristics of these screens, carrying out experiments with two devices which force a flow of air through them, thus providing data of the pressure drop as a function of air velocity. The analysis of these data has provided simple ratios of the permeability and the inertial factor as a single function of porosity.