COMPARATIVE STUDY OF SLOSHING PHENOMENA IN VARIOUS TANK GEOMETRIES UNDER MULTIPLE DEGREES OF FREEDOM

Sloshing is a nonlinear and complex phenomenon that gives rise to loads at the fluid-structure interface leading to enormous pressure buildup in partially filled tanks. In the present study, the sloshing response of four types of axisymmetric tank geometries-cylinder, sphere, capsule, and 1:10 scaled model of NASA Space Launch System liquid hydrogen tanks-have been compared in various degrees of freedom. Due to symmetry of the vessels considered, the degrees of freedom were reduced to four: pitch, spin, heave, and surge motions. Total volume and water volume were the same for all tank geometries. Computational analyses of the fluid domain were performed using ANSYS Fluent. The effects of sloshing on the free surface, impact pressure, and wall moment are presented. The impact pressure is maximum for the spherical tank when subjected to surge motion, 40 kPa. The wall moment effect on the centroid of the tank is maximum for the capsule-shaped tank when subjected to spin motion, 14 Nm. Thus surge motion is critical in comparison to other motions for defining the tank's structural integrity. The particle fluctuation is decreased as the free surface area is increased, which is why spherical geometry offered greater structural stability in comparison to other shapes.