The Significant Effect of Disk Plate and Cone as an Air-Core Suppression Mechanism inside a Liquid Draining Tank

This study delves into mitigating the formation of an air-core vortex, a common occurrence during liquid drainage in tanks, known to impede the draining process and potentially decrease the tank's efficiency and longevity. The research explores passive measures to control the emergence of this vortex. Computational fluid dynamics simulations using OpenFOAM were employed to investigate the impact of two distinct geometries, a disc plate and a cone on the formation of the air-core vortex during liquid drainage. Various drainage behaviours were observed and the changes of the draining process can be grouped into three stages which are normal regime, transitional regime and air-core regime. The introduction of a disc partially prevented the formation of the air-core vortex. On the other hand, the cone-shaped enhanced the discharge coefficient and the mass flow rate. Notably, a cone with a diameter of 2d, positioned at a height of H=d above the outlet proved most effective in diminishing the critical height and strength of the vortex. With this configuration featuring the bluff-body, the critical height was reduced by 97.55%, while the discharge coefficient and mass flow rate saw an increase of 42.23%.