Numerical study of liquid sloshing in 3D LNG tanks with unequal baffle height allocation schemes

摘要

Tank sloshing is a hotspot issue in the design of a vessel. The liquid in a partially filled tank sloshes along with the ship. Except the negative effects to the stability of the ship, the sloshing phenomena may damage the wall of the tank due to the attacking pressure. Therefore, the control of the tank sloshing is one of the researches emphasizes. While the baffles in tanks have positive effect on the control of the tank sloshing, so we compare influence of different baffle factors, such as the number of baffles, the liquid rate, excitation frequency. Then compare the effect by investigating the wave height, spectrum, hydrodynamic force and the velocity vector. The simulation processes are executed in STAR-CCM+. In the numerical simulation of the tank sloshing, we obtained a deformation at the peak of the wave height by adjusting the factors in the k - epsilon model, which is more approximate to the experimental results. Moreover, in order to obtain the wave height through the direct measurement of the liquid height, we derive the relationship between the liquid height and the wave height. Finally, we proposed an unequal baffle height (UBH) allocation scheme. Then compared the performance of UBH scheme with the equal baffle height (EBH) scheme which has the same baffle number under the condition that the total height of all baffles is the same. The performance of different baffle height allocation schemes are compared by setting different baffle height gradient. Numerical simulation results showed that the allocation of the baffle height has effect on the control of tank sloshing. The UBH scheme with the proper baffle height gradient performs better than the EBH scheme when we take no account of the baffle strength.