Experimental Study On The Effect Of Laser-induced Eccentric Bubble Collapse On Droplet Splashing By High-speed Photography

Droplet cavitation phenomenon widely exists in industrial,biological and medical fields.The dynamic behavior of liquid droplet cavitation collapse will lead to splash,burst and other abundant phenomena of droplet.When bubble is produced at different eccentric position in the droplet,the shape change of the droplet affected by the bubble will be more complex.Therefore,it is necessary to study the droplet splash caused by different eccentric bubble.Based on the laserinduced high-speed photography experimental system,this paper has carried out a detailed experimental study on the collapse dynamic behavior of the eccentric bubble formed in the inverted drop and the splash shape of the drop in the Y axial direction,the X axial direction,the 45 ° axis direction and the-45 ° axis direction respectively.Firstly,for the eccentric bubble in the same direction,according to the different splashing patterns of the droplets,the splashing process of the droplet at three typical eccentricities and the splashing transition process at two atypical eccentricities are determined.The experimental images are displayed and analyzed in detail.The results show that for the eccentric bubbles in the Y axial direction,the droplet splashes are mainly non-splash,scattering splashes and spike splashes.The shrinkage trend of the bubble wall is oblate,elongated and ellipsoid.For the eccentric bubbles in the X axial direction,the droplet splashes are mainly scattered splashes,trident splashes,as well as trumpet splashes on the right and conical splashes on the left.The shrinkage trend of the bubble wall is spherical,broad bean shaped,and elliptical.For the eccentric bubbles in the direction of 45° axis,the droplet splashes are mainly the root splashes on the right and the scattered splashes on the left,scattered splashes,as well as trident splash on the right and the scattered splashes on the left.The shrinkage trend of the bubble wall is elliptical and broad bean shaped.For eccentric bubbles in the direction of-45 ° axis,the droplet splashes are mainly scattered splashes,trident splashes on the right and scattered splashes on the left,as well as root splashes on the right and spike splashes on the left.The shrinkage trend of the bubble wall is broad bean shape,ellipsoid shape and cone shape.Secondly,the main peak of droplet splash and the change of droplet splash angle are analyzed.The results show that for the eccentric bubbles in four directions,when the initial position is close to the surface of the droplet,the main peak of droplet splash increases the highest and the fastest.The spatter angle of the droplet first increases and then decreases.Finally,based on the theory of bubble collapse time,the influence of eccentricity on the bubble collapse time and the correction coefficient of bubble collapse time are analyzed.The results show that the correction coefficient of bubble collapse time decreases with the increase of eccentricity in the Y axial direction,and increases with the increase of eccentricity in the other three axial directions.