The Analysis Of Droplet Movement In High Voltage Electrostatic Atomization

In recent years,the high-voltage electrostatic atomization technology is more and more widely applied in daily life and industrial production.The technology has been applied to many environmental protection fields,such as industrial dust removal and desulfurization denitration.In this paper,atomization experiments were carried out using a non-powered cavity atomizing electrode as a discharge electrode and the fogging process was recorded with a PCO high-speed camera.The micro-dynamics law of the droplet in the high-voltage electrostatic field was studied through the formation and fracture of Taylor cone,the droplet movement in the electric field,Rayleigh scattering of droplets as well as the relevant motion parameters obtained in the atomization process.The results show:(1)In the cavity atomization device,the discharge current is proportional to the discharge voltage;the discharge current is inversely proportional to the atomization electrode diameter,but the current values are not much different;the discharge current is inversely proportional to the discharge spacing.(2)The discharge current is proportional to the taper angle of Taylor cone,and the taper length is inversely proportional to the voltage.Taylor cone is fractured under the action of the electric field force.The main fracture form is the liquid bridge fracture,and the surface charge of the liquid bridge is concentrated in two ends with small radius of curvature,resulting the stability at both ends of the liquid bridge less than other parts,which makes the liquid bridge more easily deformed along the direction of the electric field line,and the deformation rate is proportional to the voltage.(3)Both the atomization voltage and the droplet size have an impact on the atomization half-angle.Under the same voltage,the atomization half angle is inversely proportional to the droplet size.Under the same droplet size,the atomization half angle is proportional to the voltage.When a droplet moves in the electric field,the trajectory of the large particle size droplet will be deflected,and the larger the particle size is,the more obvious the trajectory is.Through analyzing the droplet acceleration and velocity,it was learned that the droplet moved with changing acceleration in the field,and when the voltage is constant,the droplet initial acceleration is inversely proportional to the particle size,and when the droplet size is constant,the initial acceleration is proportional to the discharge voltage.As the droplet moves away from the atomization electrode,and the electric field gradient is weakened by the negative corona electric field formed by the droplet,the electric field force reduces rapidly.Meanwhile,the droplet is affected by the air resistance,resulting in sharp decrease of droplet acceleration,and the droplet does variable acceleration movement in the electric field.(4)The droplet will break again while moving in the high-voltage electrostatic field due to surface tension,electrostatic force,electric field force,its own shape and other factors of instability.At a distance 0.935 mm from the electrode,the broken satellite droplet shows reverse movement.At a distance 3.435 mm from the electrode,after breaking,the acceleration of a small particle size droplet is greater than that of a large particle size droplet,and the acceleration of the droplet after breaking is greater than that of the droplet before breaking.Secondary breaking of droplets in the electric field is more conducive to uniformization of the droplet size.By analyzing the influence of voltage on the formation and fracture of Taylor cone and the process of droplet movement and breaking,the paper summarizes the relationship between the parameters as well as the cavity atomization rule,which is of great significance to the application of cavity atomization.