A novel adjustable air-assisted spraying unit for orchardsprayer

摘要

Air flow is an essential factor which significantly affect the spray deposition on the leaves offruit trees. Most of air-assisted orchard sprayers can't adjust the air volume. Insufficient air volume could wake droplets penetration, and excessive airvolume could push droplets out canopies to cause environmental contamination. Air volume of air-assisted spraying system should match the size and density of canopy.Air flow is an essential factor which significantly affect the spray deposition on the leaves of fruit trees. Most of air-assisted orchard sprayers can't adjust the air volume. Insufficient air volume could wake droplets penetration, and excessive air volume could push droplets out canopies to cause environmental contamination. Air volume of air-assisted spraying system should match the size and density of canopy.In order to control the air volume of air-assisted orchard sprayer effectively, a novel adjustable air-assisted spraying unit was developed. This unit consists of air volume control component, spraying module, bracket and power supply. A brushless motorwas adopted to drive fan blades, which could react quickly in the range of 0~7500 rpm in real-time by controller. Based on the unit, the characteristics of the airflow field under different air delivery parameters (outlet area, rotating speed and fan size) were studied Also, deposit of distribution of various nozzles with two different spraying angles were tested in the lab. Through a series of experiments, the relationship between droplets movement with different spraying angles and airflow was obtained to optimize the parameters of air-assisted spraying unit for orchard sprayer. Results showed that the airflow diffusion angle of the fan is about 44.5 ° according to turbulent roundjet model, and the delivery direction and distance of the droplets could be controlled well by adjusting air volume of the air-assisted spraying unit Finally, 40°hollow cone nozzle matching 20-inch fan were chosen as the optimal combination for pesticide variable rate application in orchard.