Drop Tower Setup to Study the Diffusion-driven Growth of a Foam Ball in Supersaturated Liquids in Microgravity Conditions
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The diffusion-driven growth of a foam ball is a phenomenon that appears in many manufacturing process as well as in a variety of geological phenomena. Usually these processes are greatly affected by gravity, as foam is much lighter than the surrounding liquid. However, the growth of the foam free of gravity effects is still very relevant, as it is connected to manufacturing in space and to the formation of rocks in meteorites and other small celestial bodies. The aim of this research is to investigate experimentally the growth of a bubble cloud growing in a gas-supersaturated liquid in microgravity conditions. Here, we describe the experiments carried out in the drop tower of the Center of Applied Space Technology and Microgravity (ZARM). In few words, a foam seed is formed with spark-induced cavitation in carbonated water, whose time evolution is recorded with two high-speed cameras. Our preliminary results shed some light on how the size of the foam ball scales with time, in particular at times much longer than what could be studied in normal conditions, i.e. on the surface of the Earth, where the dynamics of the foam is already dominated by gravity after several milliseconds.
KeywordsFoam Mass transfer
The authors thank the team from the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH) for valuable technical support during the finalization of the setup and the measurement campaign. The European Space Agency is acknowledged for providing access to the drop tower through grant HSO/US/2015-29/AO ”Diffusion-driven growth of a dense bubble cloud in supersaturated liquids under microgravity conditions”. This work was supported by the Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation programme funded by the Ministry of Education, Culture and Science of the government of the Netherlands. Finally, we wish to thank the Spanish Ministry of Economy and Competitiveness for supporting the building of the experimental facility through grants DPI2014-59292-C3-1-P and DPI2015-71901-REDT, partly funded through European Funds.
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