| With the maturity of pneumatic aid and electrostatic spray technology,more and more pneumatic aid electrostatic sprinkler is used in the control of fruit tree diseases and insect pests,which has the characteristics of reducing pesticide dosage and improving pesticide utilization rate.The traditional gas-assisted electrostatic nozzle has narrow gas flow channel and high charging voltage,which leads to the phenomenon of large supporting power,thus affecting the operating efficiency of the sprayer.Aiming at the planting mode of short anvilled-orchard,this paper designed and developed a kind of air-assisted electrostatic sprinkler and spray system based on the chassis of large-height gap crossing sprayer,and carried out an experimental study on the atomization performance and deposition rule of air-assisted electrostatic sprinkler based on its working parameters.The main research contents of this paper are as follows:(1)A gas-assisted electrostatic nozzle was designed and developed according to the principle of jet flow,and the gas flow channel and electrode ring of the nozzle were numerically simulated and optimized.Firstly,the numerical simulation and experimental verification of the nozzle outflow field are carried out.The flow velocity at the nozzle outlet decreases from 250m/s to 9m/s within 1m,which can meet the requirements of the operation.Then,three electrode rings with different thickness(1mm,2mm,4mm)were simulated.The results show that the electric field intensity increases with the decrease of the electrode ring thickness.At the same time,1mm electrode ring thickness is selected according to the requirements of the processing technology.(2)An experimental study on atomization and charge-electric performance of air-assisted electrostatic nozzles was carried out.Performance parameters such as nozzle flow rate,charge-mass ratio,droplet volume diameter and spray Angle were studied by the experimental method.The results showed that,with the increase of gas pressure,the gas flow rate increased linearly within 4～12m~3/h.When the diameter of the liquid tube is 0.6mm,0.8mm and 1.0mm,the liquid flow rates are 140～190m L/min,180～260m L/min and 200～300m L/min respectively.The charge-mass ratio of the electrostatic nozzle increases with the increase of gas pressure,and increases first and then decreases with the increase of charging voltage and liquid pressure.The middle diameter of droplet volume decreases with the increase of gas pressure and charging voltage,and increases with the increase of liquid tube diameter.According to the test results,when the liquid pressure was 0.8Bar,the gas pressure was 0.5Bar,the charging voltage was 3000V,the liquid tube diameter was 0.8mm,the charge-mass ratio was2.9m C/kg,the middle diameter of the droplet volume was 59μm,and the spray Angle was 17.1°.(3)Through indoor simulation tree test,the fog droplet deposition law of air-assisted electrostatic nozzle was carried out.Orthogonal test was used to study the influence law of nozzle working parameters on the positive and negative fog droplet deposition amount of blade.The results showed that the ranking of significance of the influence on the fog droplet deposition amount of blade front was liquid pressure>gas pressure>charging voltage.The ranking of significant influence on the deposition amount of fog droplets on the back of blades is charging voltage>liquid pressure>gas pressure.The vertical fog meter was used to test the uniformity of droplet deposition under three different spray head spacing(250mm,300mm and 350mm).The research results showed that the droplet deposition was more uniform when the spray head spacing was 250mm.(4)Field experiment and research on air-assisted electrostatic spraying system were carried out.According to the planting mode of Yuquanying vineyard in Ningxia,a air-assisted electrostatic spraying system was designed and developed based on the chassis of a large-height gap cross-row spray machine,and field deposition test was completed.The gas help type electrostatic spray system can significantly improve the droplet deposition density,especially in proximal and middle plant,increase 64/cm~2and 68 drops/cm~2,the gas to help type electrostatic spray system can significantly reduce the diameter of droplets size,especially near end and upper,decrease 17.4%and8%respectively,the gas to help type electrostatic spray system can increase the droplets deposition quantity,Especially the proximal and upper parts were 0.063 L/cm~2 and 0.05L/cm~2,respectively. |
