This paper provides an overview of the Sloshel project, aspects of which are further described in other ISOPE 2009 papers (Kaminski, Bogaert, 2009; Malenica, Korobkin, Ten, Gazzola, Mravak, de Lauzon, Scolan, 2009; Maguire, Whitworth, Oguibe, Radosavljevic, Carden, 2009; Wang, Shin, 2009). The Sloshel project is a Joint Industry Project to collect data from full-scale sloshing experiments using unidirectional focused waves impacting on a fully instrumented LNG carrier NO96 membrane containment panel and a concrete block within a rigid vertical wall. The paper sets out the relevance of the project within the overall methodology for the sloshing assessment of partially filled LNG tanks. It describes the experimental set-up, the parameters tested and numerical evaluation leading to new insights into the characteristics of LNG tank sloshing impacts and the influence of hydro-elasticity. The paper concludes with a summary of the numerical methods being developed and validated with this full-scale experimental data.
Sloshing assessment of a membrane LNG carrier has traditionally been carried out using small-scale (1:30 – 1:60) model tests, together with numerical simulations, and further supported by 40 years of operating experience. The global behavior of the liquid, which is ruled by Froude number, is the same at small scale and scale 1. This does not mean that the local behavior is also the same and that the impact pressures and durations obtained at small scale can simply be scaled by Froude/Euler scaling factors to full scale. Locally different phenomena, like the compressibility of the escaping or entrapped gas, are involved. These local phenomena may be ruled by other scaling laws than Froude and could be predominant. Moreover, increasing demands for operational flexibility in LNG shipping and the development of an offshore LNG sector highlight the need for accurate prediction of sloshing effects in partially filled LNG tanks. This brings into question the accuracy of present experimental and numerical models for these conditions.