Analysis of Turbulent Air Flow Characteristics Due to the Presence of a 13 × 30 Threads·cm−2 Insect Proof Screen on the Side Windows of a Mediterranean Greenhouse

Abstract

Insect-proof screens are a frequent passive method to restrict the entrance of insects into greenhouses. However, the installation of these screens also has a negative effect on natural ventilation, which is reflected in the turbulence and velocity of the airflow inside the greenhouse. The turbulent characteristics of airflow through an insect-proof screen installed in the greenhouse windows have not been studied thoroughly in the literature. The present work focuses on the use of two simultaneous 3D sonic anemometers to study the impact of the use of a 13 × 30 threads·cm−2 insect-proof screen on the turbulence properties of the micro and microscale airflow turbulence. Four tests have been carried out in windward-oriented side windows of a Mediterranean greenhouse. Results demonstrate that the approach of using two simultaneous 3D sonic anemometers for the first time allows one to observe that the effect is different for the three components of the velocity vector field, and there is a strong connection between the simultaneous conditions inside and outside of the greenhouse. Useful information and data on the effect of using a 13 × 30 threads·cm−2 insect-proof screen are also provided. To give details on the impact of screens in the turbulent properties of ventilation is essential for any commercial distribution, as well as providing important data in the design and development of more efficient insect-proof screens.

Semi-analytical calculation of pore-related parameters of wire/woven screens

“…In greenhouses, insects are vectors of diseases to crops, and the use of IPSs represents a barrier to restrict the entrance of insects [10], reduces the use of pesticides [11], and prevents the escape of insect pollinators [12]. However, IPSs reduce ventilation rate, being detrimental in the microclimatic conditions within the greenhouse (temperature and humidity) [13].…”

Improvements in the Characterisation of Permeability and Inertial Factor of Insect-Proof Screens through Pressure Drop Coefficients

“…Thanks to the installation of IPSs, harmful insects are prevented from entering [3,4] and beneficial insects are prevented from leaving [3]. The main drawback of its use is the reduction of natural ventilation capacity in greenhouses [5][6][7], due to the significant pressure drop caused by their presence [1] also leads to a drastic reduction in airflow energy passing through the IPS [8]. e.g., In a greenhouse with IPSs it was identified more temperature and humidity levels [6], and lower airflow velocity [9], than in a greenhouse without IPSs.…”

“…Thus, other important applications of these screens are homes to get a passive protection of humans from insects [10], or even in farms with the purpose of protecting animals from diseases transmitted by insects and bugs [11]. Another important consequence of using insect-proof screens is mixing enhancement [8]. However, mixing is not as strong as in other more intense mixing applications [12,13].…”

Estimation of the aerodynamic tortuosity of woven/wire screens

“…They are used in homes to protect humans from insects that transmit serious diseases such as malaria [5], in farms to prevent the passage of insects that can transmit diseases to animals [6] or in greenhouses [7] to prevent the entry of insects that seriously affect crops. Unfortunately, screens at ventilation openings drastically reduce the natural ventilation capacity of these [8], reducing the energy of the airflow when entering through vents [9]. This reduction in the ventilation capacity has the consequence of increasing the temperature and humidity inside the building/greenhouse [10], which can be a serious drawback at certain times of the year.…”