Experimental Study And Numerical Simulation Of Pressure Spray Nozzle Atomization

In the agriculture application protection,the nozzle is the atomization device of the spraying system in the agriculture application and the core component of the spraying operation.Pressure spraying nozzle has the advantages of good atomization effect and low energy consumption,which is often used in the field of agricultural plant protection.In order to provide theoretical support for the rational selection of spraying nozzles,and to provide a theoretical basis for the droplet drift law of plant protection spraying application,this paper explored the atomization characteristics and droplet drift characteristics of pressure spraying nozzle by combining theoretical analysis,wind tunnel experiment and numerical simulation methods.The main work of this paper is as follows:(1)Analysis of spraying nozzle atomization mechanism and droplet drift theory.According to the liquid atomization mechanism,the three forms of droplet breakage(direct droplet fragmentation,indirect liquid column fragmentation and indirect liquid film fragmentation)as well as the nozzle structure and pressure application nozzle atomization principle are theoretically analyzed.In the process of droplet drift,the causes and influencing factors of droplet drift are analyzed theoretically.The influencing factors of droplet drift are the physical and chemical properties of the liquid itself,droplet size and droplet velocity,and other external factors.In addition,the movement process of droplets in the process of drift and the force process in the movement of droplets are analyzed theoretically.(2)Research of spray nozzle atomization characteristics.Nozzle atomization characteristics research experimental platform(measurement system of droplet information,spraying system,three-dimensional movement control system)was built to study the droplet characteristics after nozzle atomization.In the experimental study of nozzle atomization characteristics,the effects of nozzle structure,spray pressure and spraying adjuvant on the atomization characteristics were analyzed,and the spatial distribution model was established with the droplet size and velocity as the index under different nozzle,different spray pressure and different spraying adjuvant.The conclusion is that the droplet size increases with the increase of distance in the horizontal direction.The droplet size of LU120-03 nozzle is smaller than that of IDK120-03 and AD120-03 nozzles,and the droplet velocity decreases with the increase of distance in the central position and horizontal direction of the nozzle.The four spraying adjuvant solutions of Maisi,Surun,Maidao and Adsee AB-600 adjuvant can increase the droplet size and droplet velocity.(3)Research of side wind droplet drift characteristics.The experimental study of droplet drift characteristics was carried out in the wind tunnel,measuring the droplet drift at a horizontal distance from the nozzle downwind,and the droplet drift was normalized to the drift amount on a case-by-case basis,analyzing the nozzle type,spray pressure and side wind velocity on the droplet drift characteristics,and establishing the nozzle type,spray pressure and side wind velocity on the droplet drift deposition distribution model,respectively.The droplet drift deposition distribution results of each nozzle show that the droplet drift decreases with the increase of horizontal distance.When LU120-03 nozzle and AD120-03 nozzle are at the horizontal distance of 2 m to 4 m of the downwind outlet,There is little difference in normalized drift between the two.When the distance is 4 m to 6 m,the normalized drift of LU120-03 nozzle is larger than that of AD120-03 nozzle.The droplet drift near the nozzle outlet generally decreases with the increase of wind velocity,and the droplet drift away from the nozzle increases with the increase of wind velocity.The droplet drift increases with the increase of spray pressure.And according to the droplet drift of different spraying nozzle to establish the nozzle LU120-03,IDK120-03 and AD120-03 side wind velocity and spray pressure of the multiple linear regression model.(4)In the numerical simulation,the particle migration and deposition process under crosswind was simulated and analyzed.By comparing the particle density nephogram with the experimental results,it was found that the numerical simulation results were somewhat different from the experimental results,but they were basically consistent with the experimental results on the whole.