Numerical Simulation On Transport Characteristics Of Micro-Droplets In Wire-Plate Electrostatic Equipments

Electrostatic equipment is widely used in dust and fog removal and plays an important role in power plant desulfurization and denitrification combined cycle of coal gasification and other processes.The study on the motion characteristics of droplets in electrostatic equipment is helpful to reveal the defrosting mechanism,provide new ideas for water-saving of cooling towers,and provide guidance for the design and optimization of electrostatic equipment in engineering practice.In this paper,the multi-field coupling model of electric field flow field and droplet dynamic field is established by numerical simulation,and the calculation method of flow field,electric characteristic calculation method and droplet control method are given.The main content includes the following aspects:Firstly,the interaction between flow field and droplet power field in electrostatic equipment is studied.The results show that the influence of laminar flow and turbulent flow on droplet motion is not significantly different in the regular electrostatic equipment.The larger the voltage,the stronger the electric field in the electrostatic equipment,and the easier the droplet to deflect towards the plate.On the other hand,if the diameter of the droplet increases,the effect of electric field force on it will be enhanced.On the other hand,if the diameter of the droplet increases,the downstream of the cathode line will easily form a wake,and the fluid close to the cathode line will be more easily dispersed.As the droplet size decreases,the proportion of drag force on the droplet increases,and the droplet with small size is more affected by the flow field.The weakening of the electric field leads to the decrease of the y-direction velocity component of the droplet,making it more difficult for the droplet with small size to be collected.Then,the influence of ion wind effect on droplet performance was studied.The initial form of ionic wind effect is vortices.In a two-dimensional structure,four vortices are formed near each cathode line.The cross structure is arranged with the cathode line as the center.The upstream vortex of the cathode line has the effect of aggregation and the downstream vortex has the effect of divergence.When the dimensionless parameters of ion wind are greater than 0.4,the effect of ion wind cannot be ignored.The closer the droplet inlet is to the plate,the more easily it is affected by the vortex of ion wind,and then the phenomenon of droplet reflux is generated.As the droplet inlet is close to the center line,this phenomenon gradually disappears.The larger the ionic wind intensity is relative to the driving force of the flow field,the more obvious the ionic wind effect is,which will increase the collection time of droplets in the electrostatic equipment,which is not conducive to the collection of droplets.Finally,the effect of variable inlet width electrostatic device on droplet motion is studied.The airflow forms vortex at the entrance of the narrow inlet electrostatic equipment,which leads to a larger backflow phenomenon of the droplet.After the airflow enters the electrostatic equipment,the flow velocity decreases,so the relative effect of ionic wind increases,and the effect of ionic wind on droplets also increases Ion wind effect is amplified in the narrow entrance to the electrostatic equipment,makes some droplets in electrostatic equipment stay longer,but the narrow entrance to the electrostatic equipment under the same flow rate and inlet flow conditions on the droplet collection has enhanced the role,on the one hand,reduce the droplet in the electrostatic equipment within the sliding distance,on the other hand makes close to plate the entrance to the droplet is more likely to be collected.