Simulation of air-assisted spray penetration and deposition of discrete sizes of water droplets from field sprayer

The computer model predictions of the velocity profiles of a jet in the presence of horizontal wind were in excellent agreement with the measured data. The vertical profile curves predicted from the plane jet theory and computer simulation were similar and agreed with the measured peak velocity discharged from a rectangular duct in still air.; At the same outlet power, air discharged at higher velocity and lower air flow rate from the outlet, deflects more in the downwind direction. The vertical velocity component dissipates at a higher rate than when the air is discharged at lower velocity and higher flow rate.; Field and laboratory studies have shown that droplet sizes with diameter less than 150 {dollar}mu{dollar}m are most effective for insect and fungus control. Dispersing pesticide solutions in smaller droplet diameters from field sprayers requires less total spray volume to obtain equivalent coverage, provided the droplets deposit on the intended target surfaces. this study shows that using an air jet ahead of the atomizer improves penetration and increases deposition efficiency of small droplets in the area directly underneath and downwind from the atomizer in horizontal winds with velocities up to 4 m/s. Without air-assistance droplets smaller than 100 {dollar}mu{dollar}m in diameter which primarily rely on gravitational force for transportation were very susceptible to drift or evaporation. Air jets were effective in directing the sprays downward in the intended spray area and improving spray penetration into canopies in the presence of horizontal winds up to 4 m/s.; Small droplets emitted from a line of atomizers along a boom directed downward by an air shield, could be expected to give high droplet deposition efficiencies with reduced drift under field condition.