An experimental and numerical investigation into flow phenomena leading to wastewater centrifugal pump blockage

Abstract

The work covered in this paper had the objective of investigating key factors in single vane pump impeller blockage using both CFD and experimental analysis. Single vane centrifugal pumps can be found in wastewater applications, where suspended solids, fibers and other flexible material can build up on the pump impeller and cause blockage and failure. It is in the pump manufacturer’s interest to design blockage resistant components while still maintaining hydraulic efficiency. Testing was conducted on a large variety of centrifugal wastewater pumps at different operating points in a purpose built test rig with suitable test material. A pump which had varying blockage performance depending on operating point was chosen for further study with CFD. Transient simulations with the SA-DDES turbulence model were carried out with the same operating conditions as in the experimental analysis. CFD has been used to highlight flow features likely to lead to such blockage, while experiments provided some insight into the significance of certain key parameters. An analysis of the CFD results showed a significant correlation between pump blockage performance and radial velocity components within the fluid domain, specifically in the impeller region. Sensitivity to blockage was found to vary with the head required of the pump. This sensitivity was further explained when applying the hypothesis of the impact of velocity components on the likelihood of pump blockage.