Author(s): James Li; Maryam Shahab

Linked Author(s): James Li

Keywords: Wastewater pumping station; Suction bell of pump intake; Vortices

Abstract: Large-scale water pumps with bell mouth intakes are broadly used by municipal wastewater services to move sewage to wastewater treatment plants. Swirling the flow when entering the suction bell of the pump intake can cause free-surface and/or sub-surface vortices, resulting in poor pump operation. To properly design the wet well of the sewage pump station, both physical and numerical models are typically used to analyze the flow condition entering the pump intake and the associated flow pattern and potential vortex formation. During the physical model testing at Ryerson University’s Centre of Urban Innovation Laboratory, the Ryerson University’s researchers found that uneven flow distributions, including vortices, were observed at the intake chamber under three pump-working conditions. The researchers analyzed alternative slot designs of the chamber entrance to achieve an even flow distribution with minimal vortices. Additionally, a tapered design of the suction bell intake was tested for potential vortex formation. The results showed that a reduced area of the entrance slot could distribute the inflow evenly in the chamber. Moreover, no vortex formation around the tapered suction bell was found under (a) a low flow condition of 10 l/s at a water level -5.10 m below datum and (b) a cleaning cycle scenario of 16 l/s at a water level -4.9 m below the datum. However, water rotations were observed at the back wall side. For tight and intense water rotations, it might cause vortex formation. This study has provided design changes that can smooth the flow and reduce vortices at the bell mouth intakes of the pump intake chamber.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221222

Year: 2022