| As an advanced plant protection technology in agricultural plant protection,aerial electrostatic spraying technology can effectively overcome the shortcomings of traditional spraying by improving the surface adhesion and distribution uniformity of pesticide on the target crop and reducing the droplet drift.This paper analyzed the shortcomings of the traditional agricultural plant protection mode and manned aircraft plant protection mode,studied the basic principles of the aerial electrostatic spraying technology,and put forward a design scheme of the electrostatic spraying system applied to the six-rotor and single-rotor plant protection unmanned aircraft system,with the feature of simplicity,flexible installation and stable performance.The plant protection unmanned aircraft spraying operation experiments were carried out for cotton and rice in Xinjiang Changji,Xinjiang Shihezi,Hainan East and other cultivation area,with the electrostatic spraying system mounted on the plant protection unmanned aircraft.In order to further improve the effect of droplet atomization,performance of charge,and the applicability of the aerial electrostatic spraying system,the process of the UAV-based aviation electrostatic spraying system was optimized.The main research contents and achievements are as follows:(1)The existing problems of domestic aviation electrostatic spray technologies were analyzed,including the low accuracy of charge measurement,low efficiency method of droplet charging,poor applicability of aviation spraying agent,and high voltage electrostatic interference system,etc.These major problems led to low utilization of pesticides and environmental pollution and other serious consequences.(2)According to the physical and chemical properties of the chemical liquid,the electrostatic atomization effect of the electrostatic agent for the aeronautical spraying developed by the Guizhou University was studied.Through relational experiments,the effect of the aviation special electrostatic liquid agent was recognized.An aviation special electrostatic liquid agent for the field operation spraying was selected,which was with heavy oil or a methyl ester as their solvent.The results showed that the charge ratio of the water agent was 3.84mC/Kg,the electrostatic agent was 4.5mC/Kg,an increase of 13.88%.The average spray angle of water-based agent was 60 °,while the selected electrostatic agent could achieved 75 °,an increase of 15 °.(3)Based on the theory of droplet atomization and droplet charge,the electrostatic atomization and the charging methods of liquid droplets were analyzed.The existing conical aerial electrostatic spray nozzles were also designed and optimized.The structure of rechargeable electrode ring was developed.The aerosol sprinklers of different aerodynamic nozzles with different structural parameters were tested.The conical aerial electrostatic spray nozzles with a length of 120 mm,a tapered annular electrode length of 15 mm,a upper mouth diameter of 40 mm,and a half open angle of 80 ° were selected as the field spraying nozzles.The flowrate and the spray width were measured.The nozzle diameter of 0.6mm,the charging voltage of 8k V and the spray pressure of 0.6MPa were determined as the static spraying parameters for the plant protection unmanned aerial electrostatic spraying system.(4)The characteristics of the unipolar spray mode and the bipolar spray mode were analyzed.The high voltage electrostatic generator of the aerial electrostatic spraying system was designed and optimized.Current parameters,system stability and applicability were tested.The system was able to provide continuously adjustable output voltage of 0 ~ ± 10 kV,The system had a dual display for and wireless on and off control,a no-load output power of 6.8W,a load regulation rate of 0.5 %,and electrostatic high voltage power quality of 1.3KG.The approaches of the connection and installation of the high-voltage electrostatic generator and aviation electrostatic nozzle were established.The developed system realized the dual-mode and UAV-based electrostatic plant spraying which contributed to high efficiency and safety of spraying operations.(5)The field experiments were carried out,including rice growth regulator spraying test and a cotton deodorization spraying test.The results of rice field experiment showed that the effect of A-type special electrostatic spraying agent for rice was higher than that of non-static electrostatic spraying agent and B-type special electrostatic spraying agent,the average heading rate respectively increased by 20% and 10%.The results of field experiment showed that the operating flight height of 1m provided the best spraying effect,the deposition rate of the droplet increased by 140%,12.22% higher than that of the non-static spraying,the boll rate increased by 18.55%.By taking the plant protection unmanned aircraft electrostatic spraying method,the droplets in the target crop surface distribution distributed more uniformly.Less loss on the utilization of pesticides and reduce the environmental pollution caused by pesticide residues were achieved. |
PDF Full Text Request