Abstract:
Eccentric reducers are traditionally recommended for the pump suction reducer fitting to allow for
transportation of air through the fitting to the pump. The ability of a concentric reducer to provide
an improved approach flow to the pump while still allowing air to be transported through the
fitting is investigated. Computational fluid dynamics (CFD) were utilised to analyse six concentric
and six eccentric reducer geometries at four different inlet velocities to determine the flow velocity
distribution at the inlet to the pump. It was found that eccentric reducers with angles greater or equal
to 15° and concentric reducers with an angle greater or equal to 20° did not pass the assessment criteria
related to the inlet conditions. Air could be hydraulically transported through all of the concentric
reducers modelled except for the 20° concentric reducer. A correctly designed concentric reducer will
not only provide a more uniform velocity distribution in comparison to an eccentric reducer, but will
allow for the hydraulic transportation of air through the reducer.
