About aerosol properties in microgravity conditions

International audienceThe temporal and spatial evolution of dispersed media is a fundamental problem in a wide range of physico-chemical systems, such as emulsions, suspensions or aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore sensitive to buoyancy which determine s the rate of sedimentation of the dispersed phase . The latter usually prevent s a detailed study of the phenomena occurring between the constituents of aerosols , such as coalescence and evaporation of drops or flocculation of fine particles . The idea of this work is to generate with a fast compression/expansion of air, populations of water drop let s and to track their evolution by optical scanning tomography in transmission mode. Parabolic flights experiments have shown the possibility to generate and accurately follow the evolution of several hundred droplets for more than 20 seconds of microgravity within a 2 mm 3 volume . First results show that it is possible to study their evaporation kinetics as well as their motion when moving in a Von Karman swirling flow. This work is part of the AEROSOL project of DECLIC EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming