A new experimental set-up for aerosol stability investigations in microgravity conditions

TL;DR

This paper presents a novel experimental setup designed to study aerosol stability in microgravity, enabling detailed observation of droplet behavior unaffected by gravity, with applications in cloud microphysics and climate research.

Contribution

The paper introduces a new instrument for generating and tracking microdroplets in microgravity, allowing detailed analysis of aerosol dynamics and evaporation processes.

Findings

Successful generation and tracking of droplets in microgravity

Ability to observe evaporation kinetics and flow-induced motion

Potential to improve understanding of cloud microphysics

Abstract

The temporal and spatial evolution of dispersed media is a fundamental problem in a wide range of physicochemical systems, such as emulsions, suspensions and aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore subject to the influence of gravity which determines the sedimentation rate of their dispersed phase. This effect can be dominant and prevent a detailed study of the phenomena occurring between the constituents themselves, such as the coalescence of drops in emulsions, the evaporation of droplets or the flocculation in suspensions. In this context, the Centre National d'Etudes Spatiales (CNES) has recently supported the development of a new instrument to produce populations of droplets, a few micrometers in radius, under controlled conditions with the objective of allowing a detailed study of their properties in microgravity conditions. The principle of this instrument is to generate, by a fast compression/expansion of air, populations of water droplets and to track their evolution by optical scanning tomography in transmission mode within a volume of approximately 2 mm3. Parabolic flight experiments have shown the possibility to generate and accurately follow the evolution of populations of several hundred droplets for more than 20 seconds. The first experimental results show that it is possible to study their evaporation kinetics or their motion when imposing Von Karman swirling flows. 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.