Simulation and Validation of the Air Flow generated by a Multi-Channel Air-Assisted Sprayer

The multi-channel air-assisted spraying can distribute air flow according to the crown diameter and be helpful to improve spray deposition and in the reduction of environmental pollution. However, the factors of air flow distribution are not clear. Computational fluid dynamics (CFD) simulation was used in this paper to investigate the influence of the fan speed (600–1800 rpm) and the distance from the air outlet (0–6.0 m) on the airflow field distribution. The measurements and the simulation results were consistent within the boundary of the test range. The results indicated that the airflow field in the central plane was basically axis-symmetric. The airflow field diffused in the central plane at a certain angle of diffusion. The air velocity first increased and then gradually decreased along the central line, and it displayed an exponential function. Within the range of 1.0 m from the air outlet, there was an obvious section of static air between the adjacent air outlets. Beyond this range, the airflow was well-distributed, and the air velocity was normally distributed at the height
$y$
. The airfield generated by the multi-channel sprayer was elliptical in its cross-section from the outlet (for
x
> 1.0m). The distance of the air supply significantly influenced the fluctuation of the velocity of the airflow, while the speed of the fan had no significant influence on the position of the confluence point of the airflow and the fluctuation of the velocity of each test section.