Characterization of aerosol emitted by impact of millimetric droplets onto a liquid film
Titre du congrès :EAC 2007 - European Aerosol Conference
Ville du congrès :Salzbourg
Date du congrès :09/09/2007
A liquid droplet impinging onto a liquid film is of both fundamental interest and practical importance to determine the potential sources of contamination in the case of scenarios of liquid falls such as dripping. During the impaction of droplets, three phenomena can occur: deposition, rebound or splash. The key parameters of these phenomena are the characteristics of the droplets (diameter di, velocity Vi, density ρ, viscosity μ and surface tension σ of the liquid) and the thickness hfilm of the liquid film. Cossali et al. (1997) and Vander Wal et al. (2006) have determined qualitatively the deposition/splash threshold for the impact of millimetric droplets as function of dimensionless numbers (Reynolds, Weber, Ohnesorge and the film parameter Sf = hfilm/di) by the visualization of droplets emitted larger than 50 μm. The water droplets emitted with a diameter (de) smaller than 50 μm evaporate rapidly. If these droplets contain some solute, they give rise to dry airborne residues. The objectives of our work are to study experimentally the emission of airborne particles during the impaction of droplets onto a liquid film and to examine the relevance of existing relations to determine the presence or not of airborne particles.