Effect Of Liquid Viscosity On Droplet Transmission Characteristics Of Long-range Air-blast Sprayer

The development of environmentally friendly and precise pesticide spray equipment is an urgent need in the field of modern agricultural plant protection in my country.Research and development of high-efficiency air blower sprayers have good application prospects.In this paper,the viscosity of the spray liquid is used as the starting point.Based on the theory of viscous liquid jet atomization,a combination of computer fluid mechanics and field tests is used to study the spray liquid viscosity on the droplet parameters of the long-range air-blast sprayer(droplet size,velocity and density).preliminary exploration of the distribution law of fog droplet clusters in the wind field.The main research contents and conclusions are as follows:(1)According to the actual spray range,nozzle structure and nozzle angle of the long-range air blower,a three-dimensional model of the external flow field of the longrange air blower is established.The numerical simulation method of the external flow field of the long-range air blower sprayer adopts the standard k-ε equation and the DPM calculation model.The physical model adopts the dynamic drag model,and the turbulence dispersion chooses the discrete random walk model.According to the actual movement of the droplets in the spray process In the process,the boundary conditions of the outlet,the inlet and the wall are set;according to the viscosity range of the pesticide liquid used for the prevention and control of citrus pests and diseases,the numerical test and the field test liquid viscosity index parameters are set.(2)The chi-square test of the droplet deposition measured by the numerical experiment and the field experiment: There is no significant difference between the numerical experiment result of the droplet deposition and the result measured in the field experiment;the correlation test result of the fog drop density shows: the fog drop of the numerical experiment and the field experiment The density correlation coefficient is larger and the correlation is strong.It shows that the simulation model of the air-driven sprayer designed in this paper can better simulate the real field spraying process,and can be used to conduct a large number of numerical experiments to explore the influence of spray viscosity on the droplet size of the air-driven sprayer.(3)Use Fluent software to simulate and calculate the external flow field of the long-range air blower sprayer,and analyze the influence of liquid viscosity on the droplet size,droplet density and droplet velocity distribution in the external flow field.The research results show that increasing the viscosity of the spray liquid can make the particle size of the droplets in the flow field larger.With the same viscosity,the particle size of the droplets decreases first,then becomes larger,and finally decreases as the axial distance increases.The change of spray liquid viscosity has no significant effect on the droplet velocity;at the same sampling point,the droplet size increases with the increase of the liquid viscosity,and the droplet density decreases with the increase of the liquid viscosity.The research methods and results of this paper can provide a theoretical basis for the design and production application of long-range air-blast sprayers.