Present paper considers experimental study of sloshing impacts on small-scaled liquefied natural gas (LNG) fuel tank of container ship. Recently LNG has gained attention as ship fuel, because it is convenient to meet existing and upcoming requirements for the main types of emissions, i.e. SOx, NOx, PM, CO2. In this study, threedimensional tank tests were conducted for two different-shaped (one- row, two-row) LNG-fuel tanks designed by Hyundai Heavy Industry. A series of model test was conducted for various filling and motion conditions. The main interest of the test was dynamic pressure on the tank walls. The measured pressure data were statistically analyzed so that the sloshing-induced pressure values of two different tanks were compared in several ways. From this study, the characteristics of sloshing load with respect to filling condition and tank shape were systematically investigated. Test results were also qualitatively compared with the existing sloshing test data of conventional LNG carrier.
For the design of LNG cargo containment system (CCS), slosh-induced load is one of critical concerns due to its potential to cause structural damage. Sloshing phenomenon inside ship cargo may have strongly nonlinear and stochastic characteristics with violent flows, resulting in large impact hydrodynamic loads, therefore computational methods have limited capability for real application. Owing to such limitation of computational approaches, experimental analysis has been mainly recommended by ship classification societies (ABS, 2006; DNV, 2014; LR, 2009).
The techniques and recommendations for model-scale sloshing test have been developed over the last few decades, and most common procedures adopt (1) time window equivalent to 5 hours in real scale, (2) sampling peak values larger than a certain thresholding value, (3) statistical analysis for the sampled peaks, and (4) estimation on extreme value from the cumulative probability.
A large facility for sloshing model test has been equipped in Seoul National University in 2010, and many fundamental and industrial experiments have been carried using this facility. Moreover, there have been several researches on experimental methodology and statistical method for impact pressure (Mathiesen, 1976; Fillon et al., 2012). Recently, a set of hydrodynamic impact tests for thermal and bubble effect has been introduced (Kim et al., 2016b).
