Numerical Investigation of Back Vane Design and Its Impact on Pump Performance

Abstract

Adding back vanes to the rear shroud of centrifugal pumps is sometimes practiced in order to alleviate large axial forces. Effective design and flow characteristics of back vanes remain obscure due to lack of knowledge associated with experimental complexities in study of this area. In this study, various design parameters of the conventional noncurved rectangular back vanes are evaluated using computational fluid dynamics (CFD). Furthermore, the complex flow structure at the rear chamber of these pumps is illustrated and discussed with the advantage of CFD which is a highly costly and taxing job if one chooses to capture it using experimental methods. Effect of back vanes outer radius, width, clearance, thickness, vane angle, and number of vanes on pump characteristics and axial thrust has been investigated. New findings of this study show that back vanes are capable of canceling the axial thrust in a large range of flow rates without a penalty to the machine efficiency, provided that suitable design parameters are selected. In addition, the best efficiency point (BEP) will not be affected by usage of back vanes. The rear chamber’s flow pattern suggest that back vanes have a repumping effect causing increased pump head at longer back vane configurations.