Abstract
When a liquid in a tank is extracted or drained through a small port at the bottom of the tank, a dip is observed on top of the liquid column. In the presence of swirling flow due to external disturbances, the dip extends rapidly and penetrates to the bottom of the tank which is termed as an air core vortex phenomenon. When this air core is fully developed and penetrates into the drain port, there will be reduction in the discharge area of liquid at the drain port. The draining time of the liquid will be affected due to change in flow rate caused by this penetration of vortex and hence it is not desirable in applications such as spacecrafts and rockets. This article deals with numerical studies performed to analyze the air core vortex formation of water in cylindrical tanks subjected to axial and radial bulk forces after the commencement of draining, using a commercial CFD software. Moreover, the experimental measurements were taken for a cylindrical tank without inclination and the validation of the 2D and 3D numerical predictions were carried out. The tank rotated at different initial rotational speeds along the axis for the generation of vortex and then drained through a centrally located drain port situated at the base of the tank. The results show that the vortex generation is augmented with increase in the radial bulk force along with a decrease in the axial bulk force which correlates to the increase in inclination of the cylinder. The entire set of simulations was also performed at two times gravity conditions. This study is of practical relevance in spacecrafts and rocket engines as the similar condition prevails in propellant tanks owing to the inclined flight path trajectory that are subjected to increased gravity forces.
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Arjun, P., Joshy, P.J. & Tide, P.S. Numerical Analysis on Air Core Vortex Formation in Inclined Cylindrical Tanks. Fluid Dyn 57, 865–875 (2022). https://doi.org/10.1134/S0015462822100329
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DOI: https://doi.org/10.1134/S0015462822100329