Dynamic Characteristics Of Drops Impacting On Small Solid Surfaces

Drop-impacting can be found everywhere in our daily life and industry,such as rain drop,adding milk to the coffee,atomization of liquid medicine,cooling system of laser and electronic devices,ink-jet,micro-structure and liquid fuel drops impacting in engine and so on.For getting the dynamic formation and the regularity of drop-impacting,this paper basing on Zhejiang Provincial Nature Science Foundation focuses on the dynamic process and change of drop formation after impacting on small solid surfaces.An experiment system has been built,and the dynamics of drop-impacting are caught by high-speed CCD camera and high-speed camera.The major contents are as follows:The dynamic processes of single drop impacting on small solid surfaces have been studied.The single drop is generated by injector,which can make it fall freely.The dynamic characteristics are caught by high-speed camera.During this process,the influences of solid surfaces size and the impacting velocity are high-lighted.MATLAB is used to analyse the data.The dynamic splashing processes of continuous drops impacting on small solid surfaces are studied as well.The ink-jet technology is used to generate continuous drops,so that the drops fall with a certain velocity.The influences of solid surfaces size,impacting velocity and scale of drops are high-lighted.Both high-speed CCD camera and high-speed camera are used to catch the dynamic processes.The data is analyzed by MATLAB.Results show that,during the process of single drop impacting on small solid surfaces,the size of solid surfaces has great influence on spreading phase.Velocity of impacting affects the dynamic processes as well.The type of formation after impact is dominated by it.During continuous drops impacting on solid surfaces,with the size of solid surfaces goes down,splashing become greater.When the impacting velocity increases,the liquid film becomes thinner,so that splashing become more intense.It also shows that the scale of drop has great influence on the splashing process.As the drops scale increasing,the number and diameter of secondary droplets and the influence of gravity grow up.Except the impacting velocity,the splashing phenomena are also affected by height of impacting.There is a optimum height of splashing.