Numerical Simulation on Deposition of Atomization Droplet of Air-assist Boom Spraying in Air Flow

Abstract

Abstract Air-assist Boom Spraying is a crucial technique and spray method of plant protection which has a significant effect on improving the efficiency of pesticide application and reducing droplet drift. Spraying drift is the main reason for the low utilization rate of pesticides, at the same time, the interaction of natural wind and the air bag wind is the main cause of spray drift. But at present, the regularity of spray droplet deposition and motion trajectory under the common influence of natural wind and air bag wind is not yet clear. The kinematics characteristics of the droplets deposition of air-assist boom spraying in the plants is investigated with numerical simulation method. The Phase Doppler Particle Analyzer (PDPA) is used to validate the numerical simulation results and it indicates that the deposition process can be well reproduced. The results show that the bigger droplets (>150 μm) get more kinetic energy from the vertical airflow and locate in windward side. These droplets are not sensitive to the horizontal airflow and are easier to deposit within a short time. The droplets with smaller size (<150 μm) are minimally influenced by the vertical airflow and suspend in the upside of the flow field. The vertical airflow not only prevents the horizontal airflow drift the droplets, but also introduces a vortex region near the canopy of the plants, which rotates the plant canopy and increases the droplet deposition on backside of the leaves. This study improves the understanding of the droplets deposition under the multi-wind fields and provides the theoretical basis for the innovation of the air-assist boom spraying system.