Experimental investigation of phase transition effects on impact pressure dynamics in sloshing flows

The safe and efficient marine transportation of cryogenic fuels such as liquefied natural gas (LNG) presents significant technical challenges, particularly under sloshing conditions where violent impact may occur. Investigating phase transition effects in LNG sloshing is crucial for enhancing transport safety, since phase transition is an inherent feature of near-equilibrium sloshing whose effects on sloshing impacts have not been thoroughly understood. This study experimentally investigates the influence of phase transition on sloshing flow characteristics and impact loads. Utilizing a customized sloshing model tank and the refrigerant R141b, sloshing experiments are conducted under both phase transition and non-phase transition conditions. By analyzing high-speed images of the sloshing evolutions, typical sloshing modes are classified. Long-duration impact pressure signals are collected and analyzed from multiple perspectives in both time and frequency domains to characterize how phase transition modifies the evolution of impact pressure waveforms. In consideration of the randomness of pressure signals, statistical analyses of pressure peaks are also performed, revealing that phase transition leads to reduced peak values, narrower distributions, and decreased variability. Furthermore, the study explores the implications of pressure rise time on dynamic structural response. The findings provide essential insights into incorporating phase transition mechanisms into impact load assessment frameworks. This contributes to the development of safer, more reliable, and cost-effective design standards for LNG containment systems in marine transportation.