Liquid Draining Through Multiple Ports: An Investigation on Air Core Vortex Formation

The phenomenon of air core vortexing in liquid draining through cylindrical tanks can have serious adverse effects on many engineering systems. Hence, suppression of such vortices is necessity in these applications. In the present work, the influence of initial rotation on vortexing phenomenon with different drain port configurations with constant port diameter (d = 10 mm) are investigated using multiple ports. In all the configurations considered, there is a concentric port (circular) in common surrounded by other ports (circular) placed equidistant from the center. In this paper, vortexing phenomenon is studied by varying the number of surrounding ports and their eccentricity. Draining is allowed through one or more surrounding ports simultaneously. Before draining, circulation is provided to the liquid column by means of rotation (40–240 rpm) using a motorized stirrer where rotational speed can be controlled. Results of this study reveal that for all the drain port configurations, as eccentricity increases, the vortex gets suppressed and hence the draining time decreases. The result also shows that the central port is the key contributor to the vortex formation and for lower values of eccentricity, as the number of surrounding ports increases, vortex is progressively suppressed. Literature reveals that all vortexing studies reported so far were either with single or two drain ports. On multiple drain ports (number of drain ports more than 2), no investigations have ever been reported. Hence, the current study is the first of its kind being presented in this paper.