Imaging the high-speed impact of microdrop on solid surface

Abstract

An experimental setup that images the high-speed impact of a microdrop onto solid surfaces is described. The drop generation system provides a stream of monosized microdrops having diameter near 100 μm and the velocity around 10 m/s. The drop train is manipulated to deliver a single drop onto a solid target by selective charging and deflection. The images of drop spreading at different times are obtained by the double-flash photography technique. Representative experimental results are given with the estimation error of time elapsed after impact below 5 μs. In addition, it is shown that drop impact kinematics can be adopted to estimate the time in the very early stages of drop spreading. Such drop delivery and optical imaging system can be used to study the fuel spray behavior in internal combustion engines and molten microdrop deposition process in droplet-based manufacturing.