Design And Experimental Study Of Pneumatic Assisted Electrostatic Nozzle And Spray System

Aiming at a series of problems such as low-quality spraying,large pesticide usage and low utilization rate of orchard spraying machinery,this paper carried out the experimental research and design a kind of pneumatic assisted electrostatic nozzle and spraying system,and provided reference for the follow-up development of orchard spraying machinery with low capacity and high efficiency.In this paper,based on previous studies,a pneumatic assisted electrostatic nozzle was designed,and the performance and deposition test of the nozzle were carried out.Two different electrostatic spray systems were designed for field experiments,and the field deposition test was carried out.The main contents of this paper are as follows:（1）The design,numerical simulation and experimental study of pneumatic assisted electrostatic nozzle were carried out.According to the principle of fluid dynamics and previous design experience,a pneumatic-assisted electrostatic nozzle was designed,and the main structural parameters of the nozzle were determined,and the nozzle diameterφ₁=9 mm,nozzle inlet diameterφ₂=45 mm,and contraction angleα=60°;the airflow velocity in the nozzle area was calculated by the fluid mechanics theory.The internal and external flow fields of the nozzle were numerically simulated by the fluid dynamics calculation software Fluent,and the numerical simulation results of the airflow velocity in the central line of the external flow field were verified by experiments.（2）The working performance test of pneumatic assisted electrostatic nozzle was carried out.In order to explore the atomization performance of pneumatic assisted electrostatic nozzle,the influence of different working parameters（air pressure,hydraulic pressure and charging voltage）on the atomization performance of nozzle regularity was explored through experimental analysis.The influence of pressure,hydraulic pressure and charging voltage on droplet size and the influence of hydraulic pressure and charging voltage on nozzle flow rate and droplet charge mass ratio was studied;the results show that the droplet size decreases first and then increases with the increase of hydraulic pressure,and the droplet charge mass ratio increases first and then decreases with the increase of hydraulic pressure.（3）The laboratory deposition experiment of pneumatic assisted electrostatic nozzle was carried out.The influence of different working parameters（liquid pressure,charging voltage and spray distance）on the droplet deposition which is on the front and back of the blade was studied by orthogonal test.The results show that in the droplet deposition test on the front of the blade,the factors were ranked from highest to lowest significance as liquid pressure,spray distance and charging voltage respectively.In the droplet deposition test on the back of the blade,the factors were ranked from highest to lowest significance as spray distance,charging voltage and liquid pressure respectively.Based on the droplet deposition test on the front and back of the blade,the optimal working parameters were A₂B₃C₁,i.e.,liquid pressure 0.5 Bar,charging voltage 20 k V and spray distance 0.6 m,which provided a reference for the later field deposition test.（4）The design and experimental study of handheld orchard electrostatic spray system were carried out.A single nozzle electrostatic spray system was designed for an ecological pear orchard in Zhenjiang,Jiangsu Province.A hand-held orchard electrostatic sprayer was designed based on the single nozzle electrostatic spray system,and field deposition experiments were carried out to study the effect of electrostatic on droplet deposition which is on the front and back of the leaf.The results showed that the electrostatic effect could not only increase the droplet deposition on the back of the canopy leaves of fruit trees,but also positively affect the droplet deposition on the front of the canopy leaves of fruit trees.（5）The design and experimental study of multi-nozzle electrostatic spray system were carried out.A multi-nozzle electrostatic spray system was designed for the close planting of dwarf rootstocks in a wine vineyard in Yinchuan,Ningxia,and the laboratory droplet deposition distribution experiment was carried out.According to the self-propelled chassis,a self-propelled multi-nozzle electrostatic sprayer was designed,and the field deposition experiment was carried out to study the effect of electrostatic on the droplet deposition on the positive and negative sides of the leaves.The results showed that when the liquid pressure was 0.5 Bar and the spray distance was 0.8 m,the variation coefficient of droplet deposition distribution was the smallest and the droplet distribution was the most uniform.To sum up,Electrostatic effect has a certain increase in droplet deposition on the positive and negative sides of the blade.