Experimental Study Of Laser-induced Cavitation Collapse And Droplet Splash By High-speed Photography

The phenomenon of cavitation in liquid droplets widely exists in industries,biomedicine,and other fields.The research on the mechanism of cavitation dynamics and droplet splash dynamics in the process of cavitation within a droplet is of great significance for the development of fuel combustion,inkjet printing,and in vitro injection technology.Based on this,this paper established an experimental platform for laser induced cavitation in liquid droplets,and explored the dynamic processes of bubble collapse and droplet splash under different pipe diameters using high-speed photography systems.Firstly,the process of bubble collapse and droplet splash is qualitatively analyzed.The droplet bubble collapse process under different radius ratios is summarized into three modes according to the droplet splash characteristics:non splash mode,scattered splash mode,and composite splash mode.Secondly,a quantitative analysis of the cavitation process in a liquid droplet was conducted,and the radius ratio had a significant impact on the cavitation dynamics and droplet splash dynamics:the larger the radius ratio,the more intense the displacement of the characteristic points at the interface between the bubble and the liquid droplet,and the more obvious the change trend of the distance between the end points in the X axial direction.Under the three splash modes,the displacement curve of the characteristic point of the empty bubble wall increases with time.In the splash free mode,the characteristic points of the liquid droplet interface rise rapidly and maintain a relatively low constant value;In the scattering and composite splash modes,the displacement curve of the characteristic point at the liquid droplet interface maintains an upward trend,with a significant slope and rapid change rate in the axial direction.The droplet splash trend under large pipe diameter conditions is weaker than that under small and medium pipe diameters.Finally,the influence of radius ratio on the bubble collapse time and the correction coefficient of collapse time in liquid droplets is discussed.The research shows that with the increase of the radius ratio,the time required for the first collapse of a bubble in a droplet gradually increases,and the delay of bubble collapse time significantly increases,while the collapse time correction coefficient under corresponding conditions gradually decreases.