Ventilation is one of the principal governing process for the control of the greenhouse internal climate, but the evaluation of physical parameters for the calculation of the ventilation efficiency is quite difficult, and especially the air velocity and direction can be unlikely obtained with strong accuracy. The use of a three-dimensional sonic anemometer allows, by means of the detection of the air velocity vector components, to obtain the airflow patterns inside the greenhouse with good accuracy and reliability. Experimental tests were carried out by means of a three-dimensional sonic anemometer in order to obtain the spatial components of the air velocity for different ventilation configurations in different points inside a naturally ventilated greenhouse. The measured values were filtered by separating the fluctuating component in order to obtain the magnitude and the direction of the average spatial component of the air velocity vector. Then, the average and turbulent three spatial components of air velocity were calculated, together with the principal turbulence parameters like total turbulent kinetic energy and normalised turbulent intensity in the three directions The results of the tests showed the airflow inside the greenhouse. Particularly the driving force, due to the external wind blowing quite parallel to the greenhouses axis, gave near the windward and leeward end of the greenhouse some less turbulent zones.
Turbulent airflow in a naturally ventilated greenhouse investigated with a three-dimensional sonic anemometer
SCARASCIA MUGNOZZA, Giacomo;VOX, Giuliano;
2002-01-01
Abstract
Ventilation is one of the principal governing process for the control of the greenhouse internal climate, but the evaluation of physical parameters for the calculation of the ventilation efficiency is quite difficult, and especially the air velocity and direction can be unlikely obtained with strong accuracy. The use of a three-dimensional sonic anemometer allows, by means of the detection of the air velocity vector components, to obtain the airflow patterns inside the greenhouse with good accuracy and reliability. Experimental tests were carried out by means of a three-dimensional sonic anemometer in order to obtain the spatial components of the air velocity for different ventilation configurations in different points inside a naturally ventilated greenhouse. The measured values were filtered by separating the fluctuating component in order to obtain the magnitude and the direction of the average spatial component of the air velocity vector. Then, the average and turbulent three spatial components of air velocity were calculated, together with the principal turbulence parameters like total turbulent kinetic energy and normalised turbulent intensity in the three directions The results of the tests showed the airflow inside the greenhouse. Particularly the driving force, due to the external wind blowing quite parallel to the greenhouses axis, gave near the windward and leeward end of the greenhouse some less turbulent zones.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
