Non-condensable gas influence on the Marangoni convection during a single vapour bubble growth in a subcooled liquid

International audience; Liquid convective instabilities during a single vapour bubble growth in subcooled FC-72 are experimentally investigated. The bubble was created on an artificial nucleation site located on a downward facing heating element. For a non-degassed liquid, convective instabilities were observed using a shadowgraphy method and tracer particles. Both stationary and oscillatory modes were observed, and this instability was found to be Marangoni convection. Comparing results with a degassed and a non-degassed liquid, it was found that the onset of Marangoni convection was due to the presence of non-condensable gases in the liquid. Finally, the combination of Marangoni convection and condensation enables us to highlight a thermal oscillator, with a change in the type of oscillatory motion during the condensation phase.