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. In order to obtain the spatial components of the air velocity for different ventilation configurations in a naturally ventilated greenhouse, a three-dimensional sonic anemometer was used. The measured values were filtered by separating the fluctuating component in order to obtain the magnitude and the direction of the average component of the air velocity vector. The use of the normalised autocorrelation function showed that the integral time scale of the turbulence ranged from 1 s to 1.5 s for all the airflow components Vx , Vy and Vz. The experimental tests carried out with different openings configurations showed that, for all the three velocity components Vx , Vy and Vz , the highest turbulence occurred with the sidewall ventilators opened, and the lowest value occurred with both the ridge and sidewall ventilators opened.
Greenhouse airflow ventilation analysis by means of a sonic anemometer
SCARASCIA MUGNOZZA, Giacomo;VOX, Giuliano;
2001-01-01
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. In order to obtain the spatial components of the air velocity for different ventilation configurations in a naturally ventilated greenhouse, a three-dimensional sonic anemometer was used. The measured values were filtered by separating the fluctuating component in order to obtain the magnitude and the direction of the average component of the air velocity vector. The use of the normalised autocorrelation function showed that the integral time scale of the turbulence ranged from 1 s to 1.5 s for all the airflow components Vx , Vy and Vz. The experimental tests carried out with different openings configurations showed that, for all the three velocity components Vx , Vy and Vz , the highest turbulence occurred with the sidewall ventilators opened, and the lowest value occurred with both the ridge and sidewall ventilators opened.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
