Vapour pocket experiments
Conference/JournalMARIN Report 141
Date31 Oct 2024
As part of the ongoing NWO-Talent Vici programme IMBOL (IMpact of a Boiling Liquid), MARIN conducted wave impact experiments in the Atmosphere facility (ATM) in 2023 to study the effect of phase on wave impacts.
This was done by examining wave impacts due to breaking waves and by using a combination of water and water vapour. The breaking waves were generated with solitons and a beach. These preliminary experiments mainly showed that at 20°C, the vapour pocket that is entrapped collapses upon impact into a very localised region near the wall. This happens because the vapour pocket undergoes phase change: in particular, condensation (vapour to liquid).
This was done by examining wave impacts due to breaking waves and by using a combination of water and water vapour. The breaking waves were generated with solitons and a beach. These preliminary experiments mainly showed that at 20°C, the vapour pocket that is entrapped collapses upon impact into a very localised region near the wall. This happens because the vapour pocket undergoes phase change: in particular, condensation (vapour to liquid).
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Rodrigo Ezeta
Senior Reseacher
we need a better understanding of the physics behind this
The collapse in turn, leads to a short-duration, large amplitude impact pressure (in the order of 70 bar!). In contrast, when the same experiment is performed with air (instead of water vapour), no collapse is observed. In fact, here the air pocket oscillates which typically gives pressures in the order of only 1 bar. This factor of 70 between these scenarios, reveals the major role of phase change in wave impacts. If such violent impacts with vapour can be obtained in laboratory conditions, could this also happen in a real tank filled with liquefied natural gas (LNG) or liquid hydrogen (LH2)?
The lower the temperature, the easier for the vapour pocket to collapse
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