Full-scale experiment on the interaction of two neighbouring low-rise insect-proof nethouses with the wind

Abstract

Insect-proof nethouses are low-cost permeable structures covered with high density anti-insect nets, which can provide efficient protection against harmful insects and environmental hazards and regulate the microclimate in favour of the protected cultivation, especially during the summer period. A full-scale experiment of two neighbouring low-rise insect-proof nethouses without cultivation was employed for the analysis of the wind velocities windward, leeward and at the interior of the insect-proof nethouses. Moreover, the wind pressures exerted on the structures were investigated. Two different types of novel insect-proof nets were used as covering materials: The 3353BT Biorete AirPlus 50 mesh with a mesh configuration that allowed for improved air exchange rates; and the OptiNet 50 mesh that provided optical exclusion of pests through incorporated additives that block specific ultraviolet (UV)-visible radiation wavelengths. Anemometers installed at different locations on the field were used to measure the velocity reduction inside and leeward of both nethouses. Specially designed pressure differential sensors were used to measure the wind loads at the nethouses' windward and leeward sides. Velocity reduction inside the AirPlus nethouse was equal to 44%, while for the OptiNet nethouse (denser mesh) this value was equal to 62%. Lower net pressure coefficients were recorded for the windward side of the enhanced ventilation technology AirPlus insect-proof net (C_P = 0.36) as compared to the denser OptiNet net (C_P = 0.47). Contrarily, at the leeward sides of the nethouses the difference between the net pressure coefficients was insignificant (AirPlus nethouse: C_P = −0.26; OptiNet nethouse: C_P = −0.22).