| 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 studied the basic principle of electrostatic spraying technology,analyzed the current status of pesticide utilization and the urgent demand for Precision Agricultural Aviation Pesticides Spraying Technology and advanced aerial spraying equipment in China.Which focused on the current status of the spraying technology applied in UAV.Consider for the advantages and disadvantages of spraying technology of UAV,a swirl electrostatic nozzle was designed,a testing system for electrostatic spraying system was built and an electrostatic spraying system applied in multi-rotor UAV was developed.Which was with the feather of simplicity,flexible installation,stable performance and low demand for pressure.A spray operation experiment indoor,which study the influence on atomization characteristics and charge performance of electrostatic spraying system,was carried out and ensure the best operating parameters.Then,a field trial was carried out to study the droplets deposition performance of the electrostatic spraying system mounted on the multi-rotor UAV.The results as follows:(1)The swirl electrostatic spraying nozzle has a lower demand for spraying pressure,the optimal spraying pressure is 1.7×10~5Pa.Among 10 electrode voltage,the optimal electrode voltage is 8kV.Among 4 electrode materials,the optimal electrode material is copper.Among three series of nozzle,the atomization characteristics and charge performance of the nozzle whose orifice diameter was 1.0mm was best.Under the optimal operating parameters,the volume medium diameter and the charge to mass of droplets was129.12μm and 0.22mC/kg,respectively.(2)The distance between nozzle tip and the target crops was 1.2m,without the electrode voltage,the swath of the single swirl electrostatic spraying nozzle was about0.75m.Compared with non-electrostatic spraying,the spray swath was increased by 0.5m and the droplets density was increased by 23个/cm~2、19个/cm~2、10个/cm~2,respectively.Of all droplets,the electrostatic force had the most effect on the droplets(between 50μm and120μm),making the deposition amount double.And the spray droplet density decreased as the droplet size increased when over 120μm.The size of the most droplets deposited on target is under 180 m.So,those electrostatic nozzles designed by our team are suitable for crops whose optimum biological size is 180μm or under 180μm.(3)When the flying height was 1m and 2m,the swath width of the electrostatic spraying system both are 4m.when the flying height was 3m,the swath width changed from 4m to 5m.And there were no significant difference between the swath width of the electrostatic spraying system with voltage and without voltage.When the flying height is2m,the deposition of droplets is highest and the deposition of droplets deposited on up,middle and under layers are 0.2982μg/cm~2、0.0812μg/cm~2和0.035μg/cm~2(with voltage).Compared to the droplets deposition of the electrostatic spraying system without voltage,the droplets deposition increased by 26.1%,18.2%and 3.6%,respectively.(4)When the flying height increased from 1m to 3m,the drift rate ascended by89.0%,10.9%(without voltage)and 71.9%、17.6%(with voltage).The farer the drift distance was,the more slowly the drift rate descended.Compared to the drift rate without voltage,the drift rate declined by 16.0%、23.5%和18.9 for each.(5)When the flying height ascended from 1m to 3m,the volume middling dimater of droplets droped by 16.27%、3.04%,6.70%、14.07%(without voltage and with voltage),respectively.Compared to the drift rate without voltage,the volume middling dimater of droplets below 1m,2m and 3m fall by 14.22%、4.42%、15.28%(first layer)and by 14.22%、13.27%and 10.18%below 1m(first layer,second layer and third second),respectively. |
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