G0500203 Development of high-speed droplet injector using syringe and observation of droplet impact

Abstract

It is essential to understand mechanisms of splash formation because droplet impacts on solid surface are key elements in technical applications such as semiconductor cleaning, ink-jet printing, spray cooling and pesticide spraying. There are many physical parameters proposed that control splashing formation after the droplet impact. Impact velocities are one of the most important parameters. In the range of high impact velocities, splash formation has been hardly investigated partially because droplets with high impact velocities can't keep spherical shapes due to the effect of air resistance. In this study, we developed high-speed droplet injector using syringe and observed droplet impact on acrylic surfaces with a high-speed photography. The result shows that the droplet dynamics after the impact is closely related with the radius of curvature of the droplet. We compared our results with the splash/non-splash boundary reported by Wai et all. (Exp. Fluids. 40 (2006) 53-59). We also investigated the relation between the radius of curvature of the droplet and the splash velocity to find that the splash velocity increases with the increase in the radius of curvature of the droplet.