Dynamics of a single droplet with different viscosity impact onto a stainless-steel surface

Abstract

The phenomena of droplet-surface interaction have important applications in many industrial fields. In different scenarios, the viscosity of the liquid droplet that impacts on the solid surface is usually different, and the viscosity of the droplet has a great impact on the results of the droplet impingement. In this paper, the phenomena of single droplets with different viscosity (deionized water, 50% glycerol/water solution, 99% glycerol/water solution) and different Weber number (We) in the range of 147.6-939.4 impacting on a flat stainless-steel plate were recorded by a high-speed camera at 4,000 fps, and the spreading behaviour of droplets with different properties were observed. The effect of droplet viscosity and Weber number on the droplet spread on the solid surface is quantitatively analysed, and the results demonstrate that the increase in Weber number has a promoting effect on the maximum spreading diameter, whereas the increase in viscosity has the opposite effect. For high viscosity drops (99% glycerol/water solution), retraction hardly occurs after the maximum spread diameter is reached. Finally, empirical correlations of the normalized maximum spread diameter as a function of the Weber number for droplet of different fluids were derived based on the present experimental data.