CONTRIBUTION TO SPRAYING NOZZLE STUDY: A COMPARATIVE INVESTIGATION OF IMAGING AND SIMULATION APPROACHES

Application of agrochemicals on crops is important for plants protection. Multiple factors influence the application of agrochemicals on plants such as climatic conditions, crop characteristics and spraying system design. There is a need for reliable methods to investigate these properties more precisely with low cost and in reasonable time. In the present study, the velocity distribution of an extended flat fan nozzle is investigated to determine the weak jet areas, which have high risks of droplet drift. Two methods are used and compared: the Particle Image Velocimetry (PIV) method used as an experimental approach versus a Computational Fluid Dynamics (CFD) with volume of fluid (VOF) integrating k-epsilon model as a simulation approach. The nozzle was operated at eight different pressures on a custom-made nozzle operating prototype while ANSYS 16 Fluent software was employed for the simulation approach. The obtained findings showed three significant results. First, the spray sheet (jet) has maximum velocity in its center. Second, the particles present in the central region of spray sheet have maximum kinetic energy and this region has the ability to hit the right target on the plant surface, while liquid particles present in the surroundings of this central area have less velocity with minimum kinetic energy and have maximum chances to be off-target during spraying. These particles can move away from the targeted surfaces easily even with very low wind velocity. Third, the study also showed that PIV and CFD simulation methods were in agreement and both showed reliable ways to measure the jet velocity and plot the velocity distribution under the sprayer nozzle. The applications of these findings are also discussed.