Vortexing Behaviour During Draining of a Liquid Through Two Unequally Eccentric Drain Ports in Cylindrical Tanks

This paper presents the results of an experimental study on the vortexing behaviour during draining of a liquid (water at room temperature) from a cylindrical tank of inner diameter D = 96 mm through two circular drain ports (d1 and d2) placed at unequal eccentricities (e1 and e2) from the tank center. e2 is fixed as 42 mm, whereas e1 is varied giving e1/e2 ratios of 0, 0.25, 0.5, and 0.75. After imparting an initial rotation (N rpm), the liquid is drained from the cylindrical tank. The critical height of vortex formation ‘Hc’ and the corresponding time of draining were recorded. The results of the present study show that vortex formation gets completely suppressed at all diameters d1 when e1/e2 = 0.5 and 0.75. Furthermore through flow visualization experiments, an upward axial flow (above the drain port) establishment is observed in this study which is thought to influence the dynamics and characteristics of the vortex air-core formation. The phenomenon of vortex intermittency is also observed in the cases where vortex formation occurs. This attempt is the first of its kind in the research history of vortex dynamics.