Experimental and numerical investigation on the spraying performance of an agricultural unmanned aerial vehicle

Abstract

This study uses numerical and experimental methods to investigate the impact of propeller-atomizer distance on the spraying performance of agricultural unmanned aerial vehicles (UAVs). A one-propeller-atomizer setup under crosswind conditions is analyzed to generalize findings for any UAV. The numerical approach employs the finite volume method (FVM) in Ansys Fluent, utilizing an Eulerian-Lagrangian framework, the SST k-ω turbulence model, and the multiple reference frame (MRF) technique for steady flow field and unsteady particle tracking. The model incorporates the propeller, atomizer, crosswind, and ground effect interactions. The influence of propeller-atomizer distance on spraying performance was evaluated through a series of high-resolution tracking simulations on three test cases. The results were experimentally validated using smoke and laser sheet visualization to track particle behavior. Results reveal a strong correlation between propeller-atomizer distance and spraying efficiency, highlighting key factors such as coverage, particle distribution, and penetrability. These findings enable improvements in UAV-based plant protection, enhancing droplet coverage, distribution, penetration, and mixing. The study suggests manufacturers consider integrating telescopic mechanisms for adjustable propeller-atomizer distances to optimize performance. If a fixed distance is required, medium-distance settings are recommended to effectively accommodate both short and tall plants. This research provides valuable insights for optimizing UAV spraying systems and advancing agricultural precision and efficiency.