LAUSR

BACKGROUND A key challenge for the UAV (unmanned aerial vehicle) spray seldom used in tea plantations is the downwash flow structure there stronger than in crops. Besides this factor the UAV spray is actually affected by the matching relationship between nozzle and pesticide. However, few of the current research focus on this aspect. As a preliminary step this study focuses on the most appropriate pesticide for a designated nozzle of the six-rotor UAV through the nozzle-pesticide relationship using the 3D computational fluid dynamics (CFD) model. This model considers the downwash flow structure effects and the nozzle spray performances in hover. Nozzle FVP110-02, widely used in the six-rotor UAV, is designated as a representative, whilst Bifenthrin and tea saponin water, commonly used in the tea plantation, as sprayed pesticides. RESULTS The downwash flow structure of the six-rotor UAV in hover could conveniently be controlled by the flight height and the rotational speed, thereby causing the turbulence to be more stable. For nozzle FVP110-02, Bifenthrin was more appropriate than tea saponin water at the same concentration, whilst Bifenthrin and tea saponin water with the concentration of 1:1000 showed the greatest performance at the identical working condition. CONCLUSION The developed numerical model is demonstrated to be effective for investigating the matching relationship between nozzle and pesticide. Our findings could help to not only improve the UAV spray for tea cultivation but also provide guidelines for pesticide selection in crops. Further work will address rigorous quantification of the numerical simulations by the field test. This article is protected by copyright. All rights reserved.