Vortex Formation during Draining from Cylindrical Tanks: Effect of Drain Port Eccentricity

Abstract

This paper reports an experimental study on the combined effect of drain port eccentricity and port diameter on air core vortex formation in a cylindrical tank with a rotating liquid column. The study is motivated by the need to control air core vortex formation in applications like propellant feed systems of rocket engines. Based on a series of experiments in a water tank with varying discharge port diameter and port eccentricity values, the study shows how the vortex formation can be suppressed using an appropriate combination of diameter and eccentricity of the discharge port. Experiments are carried out over a range of values of initial speed of rotation (60–200 rpm) of the water column. The height of the water column at which the air core vortex extends to the discharge port, is used as a measure of the vortex growth rate. The study proposes a correlation between the critical port diameter (which suppresses vortex formation) and port eccentricity. The intermittency of vortex formation in the eccentric port configuration is also studied using flow visualization.