Abstract
Vortexing occurs during draining of liquid from tanks. We studied the critical height of a liquid being drained from tank, that is, the liquid height at the moment when the air-core vortex reaches to the drain port. We firstly performed some experiments for determining the critical height, and then based upon the information obtained from the experiments; a simple analytical expression was derived to predict the critical height. The experimental results show that the vortex suppressor, which is suggested in the present paper, could effectively reduce the strength of vortex and consequently reduce the critical height. The results also show that the new analytical expression can predict the critical height with less than 20% error when vortex suppressor is used. To the best of our knowledge, draining from tanks with bell-mouth drain ports has not been paid attention to by other authors.
Highlights
During draining of liquid from a container through a drain port, a dimple appears on the liquid free surface close to the drain port
The dimple develops into a vortex with an air core, this air-core vortex extends to the drain port as the liquid level reaches a critical height, hcr [1, 2]
Ramamurthi and Tharakan [3] studied the effectiveness of shaped ports in suppressing air vortex and they found that a stepped drain port is effective to prevent vortex formation
Summary
During draining of liquid from a container through a drain port, a dimple appears on the liquid free surface close to the drain port. Ramamurthi and Tharakan [3] studied the effectiveness of shaped ports in suppressing air vortex and they found that a stepped drain port is effective to prevent vortex formation. Sohn et al [4] used the tanks of square cross-section for suppressing the vortex formation. Lakshmana Gowda et al [2] have suggested the dish-type (or cu-shaped) suppressor to prevent vortex formation during draining after imparting initial rotation. Sohn et al [5] showed that a vane-type suppressor is effective to prevent vortex formation. The reason for using this type of port could be (1) nonaxiality of pump and tank, (2) not having enough space in the engine section; (3) the critical height reduction. We suggest a simple device (vane-type suppressor) to prevent vortex formation. Based upon the obtained experimental information, a new analytical expression is extracted to predict the critical height
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