Development And Experiment Of A Closed Canopy Spray Test Bed Integrating Rotor Wind Field And Opening Canopy

In the middle and late stages of cotton growth,the canopy is very leafy and has a tendency to produce a high depression canopy.Two types of spraying are commonly used: firstly,aerial spraying is used to control pests and diseases,but this method is characterised by rapid wind losses,crosswinds that can cause pesticides to drift away,high mechanical power consumption and uneven deposit of droplets in the canopy.Secondly,a mechanical canopy breaker is used to open the canopy,but this method tends to damage the canopy branches and leaves as well as the cotton boll.Therefore,there is a strong requirement to develop a sprayer that improves the uniformity of cotton application,increases deposition rate,reduces droplet loss,reduces wind power consumption and reduces damage to branches and leaves during canopy opening.The paper focuses on the following four aspects:(1)A low-loss,high-efficiency spraying solution combined with UAV rotor blades and a flexible canopy opening structure is proposed to achieve low-loss in-situ opening of a depressed canopy by a canopy opening device,with the rotor blade wind field increasing the kinetic energy of the airflow and forcing the droplet deposition motion and improving droplet penetration.(2)Design and dimensioning of a flexible canopy opening device and a rotor device.A flexible canopy opening device is designed to achieve flexible canopy opening in situ and to reduce the damage caused by canopy opening operations.Simulation tests were carried out to verify that the low damage canopy opening device operates with much lower loads on the cotton stems than the damage loads.The use of a rotary wing blower increases the strength of the wind field,increases the penetration of the mist droplet canopy and reduces the energy consumption of the blower.The simulation and experimental design showed that the rotor air delivery method increased airflow penetration and improved the overall droplet coverage of the system compared to the wind cylinder air delivery method.(3)The design and selection of spraying devices and frames for the spraying test rig.The results showed that the overall droplet coverage of the crop was increased by 11.9% when the nozzles were placed in the rows compared to the rows between the nozzles.The results of the frame reliability analysis using simulation software showed that the stress on the frame during operation was well below the material yield strength and met the design requirements.(4)The spray performance of the canopy spray test bench was tested.Based on the HSV leaf separation image processing method,the canopy of the test plants was scored for depression.The optimum working conditions for the spray test rig were optimised using orthogonal tests with the nozzles in the rows,the rotors in the rows and the canopy opening mechanism for application to highly closed canopies.The results of a one-way controlled test with or without a canopy opener on crops with different levels of canopy depression showed that the use of a rotor wind field feeder combined with a canopy opener for high levels of canopy depression and a rotor wind feeder for low to medium levels of canopy depression met the spray deposition requirements.The results of the performance verification tests with the Tulip Spray Test Stand showed that the Tulip Spray Test Stand improved the overall uniformity of droplet deposition on the crop.