A Flow Model for Side Chambers of Centrifugal Pumps Considering Radial Wall Shear Stress

Abstract

The side chamber flow has a fundamental influence on the performance and reliability of centrifugal pumps. However, the radial wall shear stress in the flow modeling of pump side chambers is arbitrarily neglected. The current work proposes a model for the radial wall shear stress, which is an extension of the previous paper (DOI: 10.1115/1.4047532). By using the power-law for the velocity boundary layer and the Blasius law for the wall shear stress, introducing the Ekman layer thickness expression, and deducing the Bödewadt layer thickness expression, the radial wall shear stress on the rotating and stationary disks is formulated and then integrated into the side chamber flow model. Besides, the entire flow field of the centrifugal pump is solved using the computational fluid dynamics (CFD) software ANSYS CFX. The radial wall shear stress calculated by the new side chamber flow model (NSCFM) is in the identical magnitude as CFD. Compared with pressure measurements, NSCFM makes better pressure predictions than CFD from the rear seal to the hub; however, in other areas, CFD results are closer to experimental data than NSCFM results. The flow prediction tools show that the volumetric efficiency and the shroud thrust increase with the increase in flow rate. NSCFM achieves a good compromise between calculation speed and desired accuracy.