Assessment of orchard sprayers using laboratory experiments and computational fluid dynamics modelling

Because of its complexity, orchard spray application is difficult to understand based solely on experimental work. For this reason an integrated research approach combining experiments and simulations with a continuous interaction between both was used for this study. Three commercially available, air-assisted orchard sprayers with different types of air discharge systems were characterised. Experiments were carried out to assess the spray nozzles, the spray liquid distribution and the produced air stream. Measurements were conducted under controlled laboratory conditions. Results indicated important differences in air flow patterns and liquid distribution between the different sprayers and demonstrated that the liquid distribution is directly linked to the generated air flow pattern. The architecture of the air discharge unit on the sprayer strongly influenced the air flow pattern. The results of these experiments were then compared to the results of a computational fluid dynamics (CFD) orchard spray model and the potential of using the CFD model for sprayer optimisation was evaluated.