Immersion Depth and Cavity Span During Droplet Impact Onto a Liquid Pool

Abstract Droplet impact dynamics are vital in various industries, including spray cooling, oil spill cleanup and industrial heat recovery systems. This study examines droplet impact dynamics near the surface of a water pool, including the crater formation and jet dynamics for various immiscible liquid droplets (water, silicone and rapeseed oil). Experiments were conducted over a range of Froude numbers (from 24 to 700) and Weber numbers (We from 61 to 2400). The crater depth and jet height both increased with the Froude number (Fr). At higher Froude numbers of Fr = 390, water showed the longest jet initiation time and the smallest jet height, while silicone oil 5 cSt showed the highest jet with a shortest jet initiation time. At moderate Froude numbers of Fr = 260, silicone oil 5 cSt kept the highest jet height. In contrast, at lower Froude numbers of Fr = 160, water exhibited the highest jet, and the rapeseed oil jet displayed the shortest jet initiation time. An energy analysis demonstrated that around 80% of the impact energy was utilized in cavity formation. New empirical correlations for crater depth and horizontal span are proposed as functions of the Froude number, Weber number and viscosity ratio.