New Parameter to Characterize Rankine Vortex Formation in Liquid Draining Tanks

Abstract

Air core vortexing is a subject of topical interest in aerospace engineering because it causes many undesirable effects such as cavitation in propellant feed pumps, reduced flow rate in liquid propulsion tanks, etc. Propellant tanks used in spacecraft and rocket applications are often exposed to environmental disturbances. This may cause rotating motions in draining liquid propellant and initiate the development of an air core vortex during the draining process. The air core enters the drain port and blocks the same, resulting in a reduced discharge of draining liquid propellant. Previous researchers have made use of the parameters (namely, critical submergence [Formula: see text] and time to empty the tank [Formula: see text]) to quantify vortexing, wherein contradictions are found in the effect of these parameters on the phenomenon in the light of the present results. Based on the said contradictions, it is inferred that these parameters are not capable of properly characterizing the vortexing phenomenon. Motivated to solve this serious issue, the current study has attempted to formulate a new parameter, namely, the “characteristic volume of air core,” which could meaningfully characterize the vortexing phenomenon. The new parameter is found to bring to light both the unsteady as well as the time-averaged characters of the vortexing phenomenon.