LNG Sloshing: Characteristics and Scaling Laws

摘要

Understanding the local behavior of sloshing pressure is essential for the design of LNG containment systems, particularly for operations in offshore environments. Extensive sloshing experiments have revealed that local pressures at temporal resolution on the order of 20 kHz and spatial resolution of 5 mm for scaled models up to 1:20 are stochastic; peak pressure varies dramatically from cycle to cycle even under a simple harmonic excitation in 1 degree of freedom. In addition, such pressures are strong functions of local geometry such as corrugations and raised invar edges, as well as physical and thermal conditions of the ullage. As such, the phenomenon is very challenging for predictions using existing numerical algorithms. To obtain proper design values for the containment system, scaled model tests must address the above parameters and appropriate scaling laws must be identified. In this paper, we assimilate fundamental aspects of sloshing from first principles to identify relevant dimensionless numbers necessary for the dynamic similarity of scaled model tests involving local pressures. Various experiments were carried out to support the relevance of such dimensionless numbers; this paper discusses experimental results and their implication in scaling.