Developmentand Experiment Researchof The Gas-Assisted Electrostatic Ultrasonic Atomizing Nozzle

With the extensive development of atomization cultivation in the agricultural field,atomization cultivation has higher requirements on the performance of the spray device,such as the size of the droplets and the amount of atomization,as well as the adhesion of the droplets to the roots of the plants.effect.At present,the devices used in the field of atomization cultivation are mainly ultrasonic atomizing nozzles,which are mainly divided into a fluid power type and a piezoelectric energy conversion type.The fluid power type atomizing nozzles have a wider spray range than the piezoelectric energy conversion type.The atomization amount is large,the droplet size is small,the structure is simple,and the energy consumption is low.At the same time,the electrostatic spray technology can effectively improve the utilization rate and adhesion rate of the droplets,reduce the drift of the droplets,and improve the efficiency of atomization cultivation.In view of this,this paper designs a gas-assisted electrostatic ultrasonic atomizing nozzle,which is mainly composed of a Laval tube,a two-stage resonance tube and an electrostatic induction ring.Firstly,the fluent simulation software combined with the orthogonal test method is used to determine the structural size parameters of the Laval tube and the two-stage resonance tube.The results show that:(1)the Laval tube has a contraction angle of 40° and an expansion angle of 12°.With a diameter of 8.4 mm,a throat diameter of 2.1 mm and an outlet diameter of3.4 mm,the Laval tube has the highest exit velocity.(2)When the angle between the two-stage resonance tube is 80° and the diameter is 4.86 mm,and the length ratio of the two-stage resonance tube is 1,the resonance performance of the two-stage resonance tube is the best.Secondly,based on the principle of electrostatic induction,a ring-shaped electrode is used as the charging electrode,and its electrical model is introduced.At the same time,Comsol Multiphysics software simulation analysis shows that the optimal charging region of the droplet is within the range of the electrode ring axial distance <60mm.The motion characteristics of the droplets during electrostatic spraying were studied.Finally,the Comsol Multiphysics simulation software was used to analyze the deformation and fracture process of the droplets,including the electric field,the potential distribution and the charge density distribution on the surface of the droplet,and the effects of different electrostatic voltage,surface tension and droplet diameter on thedeformation rate of the droplet.The simulation results show that: The deformation rate of droplets increases with the increase of electrostatic voltage,the surface tension decreases,and the diameter of water droplets increases.According to the above results,the gas-assisted electrostatic ultrasonic atomizing nozzle was tested and its working performance was tested.Firstly,the droplet size under different atomization parameters was tested.According to the experimental results,we can get:(1)When the spray height is constant,the particle size of the droplet is inversely proportional to the gas pressure and the electrostatic voltage.When the gas pressure is 0.4 MPa and the electrostatic voltage is 18 KV,the droplet size reaches a minimum of 7.8 ?m.(2)When the gas pressure is constant,the particle size of the droplet is inversely proportional to the electrostatic voltage and the spray height.When the spray height is 0.5 m and the electrostatic voltage is 18 KV,the droplet size reaches a minimum of 18.4 ?m.Secondly,Based on the orthogonal test method,the deposition distribution of droplets on the front and back of the plant under different atomization parameters was tested.The experimental results show that:(1)the electrostatic spray has higher droplet deposition rate than non-electrostatic spray.And the droplets are evenly distributed.(2)The optimal spray scheme is:electrostatic voltage is 12 KV,spray pressure is 0.3 MPa,and spray height is 0.5 m.Finally,the atomization cultivation experiment was carried out,and the adhesion effect of the droplets on the roots of the plants under different electrostatic voltages was compared and analyzed by the experimental results.It was concluded that the electrostatic droplets were more easily adsorbed on the plant roots than the non-electrostatic droplets,and with the static electricity The higher the voltage,the better the adhesion.