The effect of ethylene glycol concentration on the interfacial dynamics of the successive droplets impacting onto a horizontal hot solid surface

The present work aimed to conduct the visualization study on the effect of the ethylene glycol concentration on the interfacial behavior of successive droplets during the impacting onto a horizontal hot solid surface. The tested liquid droplets were pure water and two ethylene glycol-water mixtures, which contain 10 and 20 of ethylene glycol. A polished cylindrical plate of stainless steel (SUS 304), with the surface roughness of 0.06 μm, was utilized as a solid surface. The surface varies for temperatures of about 110 °C–240 °C. The detailed phenomena during the droplet impact were recorded by using a high-speed video camera with the frame speed of 2000 fps and the resolution of the 1024 × 768. In addition, an own developed image processing technique was also implemented to obtain the quantitative parameters, such as the spreading ratio and the apex height during the droplet impacting onto a hot solid surface. As a result, the interfacial dynamics of the successive droplets were clarified. The addition of the concentration of ethylene glycol leads to the decrease of droplet oscillation during the spreading phase and delays both the bubble formation and the presence of secondary droplets. In addition, the research also reveals that the presence of the second droplet successfully improves the wetting area of the droplet. © 2020 Elsevier Masson SAS