Study On The Dynamic Characteristics Of Single Droplet Impinging On Fine Fiber

The phenomenon of droplet impinging on fine fiber is widely existed in the field of energy and environment,in-depth study on the process of droplet impinging on fine fiber can better understand the nature of the problem,optimizing the amount of droplet capture in the process of impingement is of positive significance for practical production and modern high-tech application.At present,the research on the optimization of droplet capture is focused on the change of fiber properties under the action of gravity field,in this paper,high-speed camera is used to study the dynamic characteristics of droplet impinging on fine fiber under the action of electric field,the effects of eccentricity on the dynamic characteristics of the droplet impinging on the fiber were simulated and analyzed by using the level set method.The experimental system of droplet impinging on fine fiber under the action of electric field was designed and built,the dynamic process of deionized water droplet,glycol droplet and ethanol droplet impinging on the fine fiber at the same speed under different electric fields was observed by high-speed camera,the image data were processed by Photoshop software,and the effects of surface tension and field strength on the characteristic parameters of the droplet were analyzed.The results show that the process of droplet impinging on the fine fiber is very short,after collision,the droplet deforms,rapidly reaches the maximum spread and passes through the fine fiber,and then the liquid film retracts and repeatedly vibrates on the fine fiber to reach equilibrium;the deionized water droplet with high surface tension are suspended under the fine fiber to reach equilibrium after collision,forming suspension mode,the glycol droplet and ethanol droplet with low surface tension are separated from the fine fiber after collision,forming falling off mode;the spreading factor of the suspension mode shows a slight fluctuation in the process of decreasing due to the maximum rebound of droplets,the height of the dimensionless center liquid film appeared a large fluctuation due to the rebound,and the spreading factor of the falling off mode decreased to a stable value after reaching the maximum value,and the dimensionless center liquid film height did not appear a large fluctuation;when the electric field is applied,the droplet inclines to the positive plate,and the larger the electric field is,the more obvious the incline is;the electric field action promotes the spread of the droplet on the fine fiber axis,and the larger the electric field is,the more larger the maximum spread factor of the droplet,and the increase degree is from strong to weak in order of ethanol droplet,deionized water droplet and glycol droplet;the external electric field increases the liquid film for the first time the maximum height of retraction and the time required for the droplet to reach equilibrium state,especially in the suspension mode,are not obvious in the falling off mode.A two-dimensional physical model of droplet impinging on fine fiber is established by using the level set method,the influence of eccentricity on the dynamic characteristics of the droplet impinging on the fine fiber were studied,the variation of droplet spreading factor,pressure and velocity at the detection point with time is analyzed.The results show that the eccentricity have an important influence on the flow pattern of the droplet after collision,with the increase of eccentricity,the volume of the two small fragments that are divided into after the droplet impinging the fine fiber becomes not completely equal,and the spreading factor changes with different eccentricity the trend is the same,but when the eccentricity is 0.2mm,the ability of the fine fiber to retain the liquid is enhanced;during the impact process,the peak pressure of the fiber is related to the eccentricity,the velocity distribution of each detection point of the droplet is different,and the change trend with time is affected by the eccentricity,and the droplet reaches the minimum velocity when the liquid bridge between the liquid drop and the fine fiber breaks.