Developments To Minimize The Occurrence
Of Surface And Subsurface Vortices At
Pump Intakes
Author(s)
S. J. van Vuuren
Abstract
Surface vortices have been classified [1] and are widely used as parametric
criteria to evaluate the acceptability of the hydraulic inlet conditions at pumps.
The geometry of the pump sump, pump inlet and the flow characteristics (fluid
structure interaction) normally depict the tendency for the formation of surface
vortices. The presence of surface vortices will invariably lead to un-uniform
loading on the pump inlet, leading to vibration and possible structural failure.
Current literature [2,3] reflects the submergence requirements at pump intakes to
prevent the occurrence of surface vortices. The accepted hypothesis is that by
increasing the submergence the formation of vortices will be reduced.
This hypothesis is challenged on the basis that surface vortices can only occur
when the vertical flow component is significant and that this can be limited by
the accentuation of the horizontal flow velocity that will dissipate the vertical
flow component and thus reduce the submergence requirement significantly.
Physical and computational modelling was conducted to verify the relationship
of flow velocities on the required submergence to prevent surface and subsurface
vortices.
Keywords: pump intakes, vortices, deflector beam, vane turning box,
submergence, swirl angle, pre-rotation, horizontal flow.
1 Introduction
The criteria suggested for effective pump operation entail, the limitation of
surface vortices, ensuring a balanced velocity distribution and limiting the prerotation
at the pump inlet [4].
Keywords
pump intakes, vortices, deflector beam, vane turning box,
submergence, swirl angle, pre-rotation, horizontal flow.
Related Book
Other papers in this volume
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