Atomization Characteristics And Experimental Study Of Multi Nozzle For Electrostatic Spraying Of Boom Sprayer

Rice is the main food crop in China.With the adjustment of the planting industry structure and global warming in recent years,the occurrence of rice pests and diseases has become more frequent,and it has become one of the main reasons affecting its yield.The plant protection operation can effectively avoid the impact of pests and diseases,and ensure the yield and quality of crops.However,due to the relatively backward plant protection technology and equipment in China,sprayers have problems such as large water demand,insufficient back deposition,and uneven distribution of mist droplets during plant protection operations.This will lead to a large amount of pesticide residues,cause pollution of agricultural products,soil,water bodies,etc.,and endanger human health.The development of new and efficient plant protection equipment and the improvement of pesticide spraying technology are the research directions that plant protection experts are committed to,as well as the core requirements of China’s"double reduction"strategy.Electrostatic spray is an efficient plant protection technology.The self-propelled boom sprayer will still be the mainstream model of paddy field plant protection and control in the future.If electrostatic spraying technology and sprayer spraying technology can be combined to play a combination of innovation,it can achieve efficient spraying of pesticides and promote the sustainable development of agriculture.This article analyzes the basic principles of electrostatic spraying and the spatial distribution of the induced electric field.The simulation model of flow field,discrete fog field and space electric field is established by using Fluent software.Combined with the characteristics of the boom sprayer,an electrostatic spray test platform was set up,and the indoor tests of the charge and deposition characteristics of the droplets were carried out.Finally,the best working parameters obtained in the indoor test were applied to the modified electrostatic boom sprayer,and the field pest control effect test in the rice field was conducted.The main research contents and conclusions are as follows:（1）Based on the theory of electrostatic field and the principle of inductive charge,this paper explores the basic process of inductive charging and the relationship between the electric field strength and the effect of inductive charge.This paper analyzes the basic process of electrostatic spraying and the best way to charge droplets.By exploring the droplet breaking mechanism in the electrostatic field,a mathematical model of the maximum charge and surface tension of the droplet is obtained,which provides a theoretical basis for the selection of experimental parameters.A mathematical model of the induced electric field strength was established,and theoretical calculations were performed for the electric field strength of different numbers of sensing electrodes.The process and reason of the influence of the reverse adsorption of droplets on the charging capacity of the sensing electrodes were explored.（2）Based on computational fluid dynamics,a simulation model of coupled flow field,discrete fog field and space electric field was established using Fluent simulation software.Analyzed the change law of droplet size under non-static and electrostatic condition.The simulation results showed that the droplet charging process was mainly concentrated near the nozzle electrode,and the uniformity of the electric field distribution of the multi nozzle was better than that of the single nozzle.The smaller the distance was,the better the uniformity was.The error of the experiment is 8.5%and 14.7%respectively,which proves the feasibility of CFD simulation in electrostatic spraying.（3）In this paper,an inductive electrostatic spray test platform is set up.Laboratory tests and analysis were performed.The test parameters include droplet-to-mass ratio,droplet size,atomization uniformity and deposition amount.The charge mass ratio of droplet was measured by Faraday tube method.The maximum charge mass ratio of a single nozzle was 0.21m C/kg,and the charging voltage had a very significant effect on the charge ratio of multi nozzle.Moreover,when the charging voltage was not more than6k V,the droplet charge ratio of the multi nozzle was higher than that of the single nozzle.The particle size of droplets was measured by laser particle size analyzer.The electrostatic spray can reduce the droplet size.When the spray pressure is 0.5MPa and the nozzle spacing is 200mm,the electrostatic force is reduced by 17.4%compared with the non electrostatic D_50.The atomization uniformity test results show that the charged power can effectively reduce the variation coefficient of the spray distribution,and the electrostatic spray is 32.1%higher than that of the non electrostatic spray under the same condition,increasing the spray pressure and the variation coefficient of the fog distribution as a whole.The results of droplet deposition test show that electrostatic deposition can reduce the deposition rate while increasing the frontal adhesion rate of the droplets.The frontal attachment rate of electrostatic spray on the 3 sampling layers of the upper,middle and lower layers is increased by 27.1%,37.3%and 45.2%respectively,and the deposition volume is reduced by 25.7%,25%and 12.5%respectively.（4）The Jingguan 3WP-500 boom sprayer is preferred,and it is improved into a spray-bar electrostatic sprayer.It is formulated into two different concentrations of medicinal solutions,which are respectively used in non-static and electrostatic field pest control experiments.A non-static spray test was performed with a conventional spray nozzle spraye.The modified boom sprayer with electrostatic nozzle is used to test the electrostatic spraying method under the conditions of charging voltage of 6k V,spray water pressure of 0.4MPa,and nozzle distance of 250mm.Then count the deposition of fog droplets on the target and the prevention effect.The result is that electrostatic spray can increase the deposition of mist droplets in the lower and middle layers.The pest control effect of electrostatic nozzle and conventional nozzle is basically the same,92.1%and 95.0%,respectively,but the water consumption of electrostatic sprayer spraying methods is reduced by 60%,which significantly improves field work efficiency.