Experimental and Numerical Study on Effects of Different Excitations and Liquid Levels on Sloshing in a Large-Scale LNG Tank

The liquefied natural gas (LNG) tanks are designed with four chamfers to reduce liquid sloshing for LNG carriers. This study investigates liquid sloshing mechanism in LNG tanks under different conditions through experiments and simulations. The repeatability test verified the good reproducibility of the experiments. A series of experiments also verify the correctness of the numerical model. The LNG tank is subjected to excitations for different excitation amplitudes, pitch motion, roll motion, and their coupled excitations. The effects of different liquid levels on impact pressure and wave height are compared. The mechanism of liquid sloshing under resonant excitation is analyzed emphatically. The results show the maximum impact pressure of the pitch motion is 58.53% larger than the roll motion. The 50% liquid level has a more significant impact pressure on the tank walls. The maximum pressure appears near the lower chamfer, and the liquid velocity is often largest at the breaking point. Thus, engineers should reduce the area of the free liquid surface to ensure lower or higher liquid level in LNG tank during the pitch motion and design the chamfer reasonably to reduce the flow velocity of the liquid.