In this paper, an innovative approach is highlighted that is able to predict the sloshing impact pressure and frequencies for different LNG tank shapes. This approach is computationally efficient and flexible in geometry. It provides time accurate wall pressure results in three dimensions and 6 Degrees-of-Freedom. The results of specific test cases have been validated against experimental data for launch vehicle tank fuel sloshing carried out at NASA test facilities. Snapshots in time and some results for the wall pressure for rectangular, cylindrical and spherical test tanks are discussed to optimize the tank shape in terms of sloshing impact. An outlook providing additional simulation results for LNG sloshing in a multi-tank configuration undergoing forced oscillations in 6 Degreesof- Freedom will be presented and discussed in this paper.
The Liquefied Natural Gas (LNG) provides an efficient way for long distance transport in large vessels. The gas is cooled down to extremely low temperatures such that it can be transported in the liquid state. Hence, the liquefied gas obeys the laws of liquid dynamics. During the filling process, the LNG exercises unsteady forces on the tank walls and makes the vessel react to these forces by ship motion. The ship motion, however, is the driver for LNG sloshing in the tank. Special focus is given to the tank shape to minimize the impact pressure from sloshing LNG, see Fig. 1.(refer to the full paper) Sloshing in partially filled tanks is a complex physical process. It covers phenomena like wave propagation and liquid-structure interaction; see (Yamamoto and Kataoka and Shioda and Ashitani, 1995). Applying continuum fluid mechanics for a simulation approach, Euler and Navier-Stokes solvers provide a time accurate simulation only if an appropriate free surface determination and propagation is implemented. In consequence, computation time and required memory resources increase with increasing code complexity and accuracy requirements.
