Shock waves in two-phase bubbly liquids

Abstract

Natural gas is one of the most important global energy sources, and is commonly transported in pipelines (in gaseous state) or specially-designed LNG vessels (in liquid state). As LNG is stored inside the ship cargo containment system at atmospheric pressure and low temperatures, just below the boiling point of circa -162 ◦C (depending on the composition), small perturbations in pressure or temperature may result in phase changes between the liquid and vapor phase. During transportation overseas, the motion of the ship induces movements of the LNG inside the containment system. Sloshing may result into wave impacts that potentially cause damage to the containment system. During these wave impacts, phase changes inside the LNG fluid domain are likely to occur, which alter the fluid properties locally. Insights into these phase changes during sloshing impacts are of key importance for the accurate, efficient and safe designs of cargo containment systems inside LNG vessels. The main objectives of this dissertation are twofold : (1) the development and validation of non-intrusive measurement techniques to characterize the propagation of shock waves through multiphase fluids, and (2) quantifying the energy partitioning and emission of shock waves by collapsing vapor bubble clouds. To this aim, two novel measurements techniques are developed and validated for accurately quantifying the two-phase liquid properties and the shock wave propagation, non-intrusively. Also, the emission of shock waves by collapsing vapor bubbles is assessed non-intrusively with state-of-the-art high-speed X-ray densitometry....