evaluation of an experimental model for flat-fan nozzles drift in wind tunnel by image processing

each year, millions of liters of toxic liquid, are used to combat with pests and plant diseases in farms. the wide spread use of chemical pesticides causes great environmental hazards. particles drift is one of the main problems in spraying which results in the contamination of farm lands, humans and animals. management of particle size is regarded as the main factor in drift control. in this study, the effect of some parameters on the size of deposited particles on non-target areas was studied using statistical method. the effects of nozzle type (orifice size), spraying pressure, spraying boom height and wind speed as effective factors on drift were examined. a horizontal wind tunnel with working section of 0.47 m wide, 0.75 m height and 5.5 m long was used for testing. experiment was performed in the form of factorial split-plot based on randomized complete block design with two replications. droplets were measured in the treatment combinations of the type of flat-fan nozzle with three orifice area (11003- 0.87 mm2, 11004-1.18 mm2 and 11006- 1.8 mm2), spraying pressure (150, 275 and 400 kpa), wind speed (1, 2 and 3 m s-1) and the boom height of (0.35, 0.55 and 0.75 m). water-sensitive papers were used at intervals of 0.8, 1.6 and 2.4 m from the tip of nozzles for detecting droplets size. the factors of pressure, speed and height had positive effects on the droplet size at the desired distance, but the effect of nozzle size on droplet size was negative. in the regression model the coefficients of speed was higher than the others.