Study of airborne particles during the impact of droplets on a dry surface or on a liquid film.
C.Motzkus * (1,2) , E. Gehin (2) et F. Gensdarmes (1) - CFA 2005 - 21ème Congrès Français sur les Aérosols, 14-15/12/05, Paris.
The safety analyses of the nuclear facilities require extensive knowledge on the airborne micro-droplet, in order to assess the potential sources of contamination in the case of hypothetical scenarios of accidental falls of liquids caused by leakage or discharge from a container. There are very few data in the literature in the case of the impaction of millimeter-size droplets on the airborne particles. The objective of our work is to study experimentally the emission of the particles during the impaction on a dry or wet plane surface, in order to understand the mechanisms leading to the airborne particles. First experiments are carried out in order to study the airborne particles produced by the free falls of droplet according to the fall height. These results are faced with a semi empirical correlation, which describes the transition between deposition and splash. In the case of a dripping of 3.84 mm-diameter droplets, our results show that the splash occurs for a fall height above 30 cm, which leads to resuspension fractions between 1,9 10-6 at 46 cm and 7,5 10-6 at 80 cm.
(1) Institut de Radioprotection et de Sûreté Nucléaire/Service d’Etudes et de Recherches en Aérodispersion des polluants et en Confinement, B.P 68, 91192 Gif-sur-Yvette Cedex, France.
(2) Centre d’Etudes et de Recherches en Thermique, Environnement et Système, Université Paris XII, 61 av. du Général de Gaulle, 94010 Créteil Cedex, France.