EFFECT OF THE DOWNWASH FLOW FIELD OF A SINGLE-ROTOR UAV ON DROPLET VELOCITY IN SUGARCANE PLANT PROTECTION

Ping Zhang,Jiansheng Liu,Haitian Sun,Haiba Fu,Wei Zhang

doi:10.1590/1809-4430-eng.agric.v41n2p235-244/2021

Abstract

Protecting against the main sugarcane diseases and insect pests requires good control at the base of the plant; therefore, higher droplet penetration is required during plant protection. The objectives of this research were to explore the movement mechanism of droplets in a sugarcane protection operation using a single-rotor unmanned aerial vehicle (UAV) and establish the connection between the UAV downwash flow field and droplet penetration. By considering the downwash flow field of a single-rotor UAV in layers, a theoretical model of the vertical velocities of droplets was established, and verification experiments were carried out in a sugarcane field. The results showed that the velocity of the UAV downwash flow was the main factor affecting the final vertical velocity of the droplets, the final vertical velocity of a droplet was positively correlated with the droplet diameter, and the initial droplet velocity had no significant effect on the final droplet velocity. In the transportation of droplets, the droplet velocity quickly approached the velocity of the airflow, and the smaller the droplet diameter was, the higher the acceleration. These research results can provide guidance for the theoretical study of droplet deposition effects in sugarcane protection operations using single-rotor UAVs.

Highlights

Sugarcane is the most important sugar crop in the world, and the annual output of sucrose accounts for more than 76% of the total sugar produced (Canata et al, 2019; Feng et al, 2019; Zhou et al, 2016)
The airflow of an unmanned aerial vehicle (UAV) can improve droplet penetration during spraying (He, 2004), and UAV plant protection operations are highly efficient, are not restricted by crop growth, can deal with explosive diseases and insect pests and can avoid problems that arise in the operation of ground machinery in the middle and later stages of crop growth
To study the motion of droplets in the downwash flow field of a single-rotor UAV and reveal the influence of airflow on droplet velocity, it is necessary to analyze the forces on the droplets, establish a kinetic equation, and identify the relationship between the parameters to be solved and the initial variables

Summary

Introduction

Sugarcane is the most important sugar crop in the world, and the annual output of sucrose accounts for more than 76% of the total sugar produced (Canata et al, 2019; Feng et al, 2019; Zhou et al, 2016). Protecting against the main sugarcane diseases, such as sugarcane brown spot disease, and insect pests, such as sugarcane aphids and borers, mostly requires good control at the base of the plant; higher droplet penetration is required during spraying. The airflow of an unmanned aerial vehicle (UAV) can improve droplet penetration during spraying (He, 2004), and UAV plant protection operations are highly efficient, are not restricted by crop growth, can deal with explosive diseases and insect pests and can avoid problems that arise in the operation of ground machinery in the middle and later stages of crop growth. The operation parameters of UAVs, such as flying height, operational speed and nozzle flow, have a considerable influence on penetration (Chen et al, 2017a). When the flying height increases, the vertical velocity of the UAV downwash flow near the crop canopy

Objectives

Methods

Results

Conclusion