Air Core Vortexing in Liquid Draining Vessels: Impact of Drain Port Vanes

Vortex formation in liquid propulsion tanks can obstruct propellant flow, reduce discharge efficiency, and cause cavitation in feed pumps, posing a risk to spacecraft and rocket performance. To mitigate these ill effects, intrusive vortex suppression strategies, such as vanes, have been explored. This study experimentally investigates the effect of vanes positioned inside a circular drain port on air-core vortexing in precritical and postcritical height regimes. A newly introduced discharge number quantifies vortex suppression. Experiments are conducted using a liquid draining setup, where vanes of varying configurations are tested under different initial rotation conditions. The study measures the critical height, emptying time, and critical time, while the air-core blockage percentage and static pressure near the drain port are determined analytically to analyze vortex behavior. Results indicate that vanes enhance draining efficiency in the postcritical regime by weakening the air-core vortex but hinder discharge in the precritical regime by increasing frictional resistance. These findings have practical applications in optimizing liquid propulsion systems, ensuring uninterrupted propellant flow, reducing vortex-induced cavitation risks, and improving spacecraft engine performance. Building on these findings, the study suggests implementing a selective electro-mechanical system that deploys vanes only after critical height formation, thereby optimizing fuel management in aerospace propulsion systems.