High-speed video of a single impact wave in the Atmosphere facility (ATM) from two different angles. Here, the liquid phase is water and the gaseous phase is water vapour. The temperature increases from left to right.
Figure 2: Single wave impact as captured by a high-speed camera for four selected temperatures from The Atmosphere facility (ATM). The liquid phase is water and the gaseous phase is water vapour. Impact process before impact (top panels), impact process after impact (bottom panels)
IMBOL In 2019, MARIN together with the Phase Transition Consortium joined IMBOL (2019-2025), which is a continuation of the SLING programme (2015-2020). MARIN’s contribution to IMBOL is based on an extensive experimental campaign in the Atmosphere facility (ATM) examining the impact dynamics of a boiling liquid.
In 2021, we conducted a series of single impact wave experiments along the liquid/ vapour boundary for increasing temperature (up to 115 C) and thus, for increasing gas-to- liquid density ratio (DR). In contrast to the type of gases that are normally used in the ATM (condensable gases), these experiments looking at the vapour pressure of water further reveal the impact dynamics of a liquid that has contact with its own vapour – as is often the case in a cargo containment system (CCS) filled with a cryogenic liquid such as liquefied natural gas (LNG) or even liquid hydrogen (LH2). The experiments have shown that – when the DR is small (low temperatures) – a Rayleigh-type collapse of the vapour pocket takes place, which is accompanied by a short, large amplitude pressure peak whose magnitude can reach
up to 70 bar! As the DR increases, we observed that this effect is mitigated, and the impacts resemble something similar to the oscillation of non-condensable gas pockets. These observations are illustrated in figure 2.
Currently, we are working on a better understanding of these results by placing our experiments in the context of a theoretical model of a vapour pocket that takes into account both pocket dynamics (Rayleigh-Plesset equation) and heat transfer (Plesset-Zwick formula). This phenomenon is of particular interest to the industry, as these short-pulse, large amplitude peaks could be potentially hazardous and thus, need to be considered when designing a CCS.
The Atmosphere is a test facility to unravel the complex physics of those wave impacts. A custom-built 12.5 m long, 0.6 m wide and 1.2 m tall flume tank with a heavy, instrumented impact wall is available at the facility to study wave impacts in different conditions.
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