EXPERIMENTAL STUDIES OF THE DEPOSITION AND SPLASHING OF SMALL LIQUID DROPLETS IMPINGING ON A FLAT SURFACE
University of Erlangen-Nürnberg, Erlangen, Germany
Martin Luther Untversitat Halle-Wittenberg Institut fur Verfahrenstechnik, Halle (Saale), Germany; Energetics and Mechanical Department, Universidad Autonoma de Occidente, Santiago de Call, Colombia
Technische Universität Darmstadt, Institute of Fluid Mechanics and Aerodynamics, Center of Smart Interfaces, International Research Training Group Darmstadt-Tokyo on Mathematical Fluid Dynamics, Germany
Experimental studies of liquid droplets impinging on a flat surface have been performed, with the aim of formulating an empirical model describing the deposition and the splashing process. Monodispersed droplets at known viscosity and surface tension, produced using a vibrating orifice generator, were directed towards a rotating disc. A rubber lip was used on the rotating disk to remove any film from previous depositions. For the case of droplet splashing, a two-component phase Doppler anemometer was used to characterise the size, velocity and mass fraction of the secondary droplets.
The deposition/splashing boundary was expressed as a function of the Oh and Re number. The size distribution of the splashed droplets was expressed in terms of the log-hyperbolic, 3 parameter distribution. The two measured components of the droplet velocity and their correlation was expressed in terms of the first two moments. The size dependent number fraction of splashed droplets were correlated to a newly introduced parameter K, expressing the deviation of the wall interaction kinematics from the deposition/splash boundary. These empirical correlations are appropriate for use in Eulerian-Lagrangian particle tracking codes.