Hydraulic Loss and Internal Flow of a Pump Equipped with an Impeller with Radial and Annular Flow Channels

Abstract

To provide stable operation over a wide flow range, centrifugal pumps should have high pump efficiency at a low flow rates and high total head. A new impeller with radial and annular flow channels that has higher pumping performance than conventional design impellers with the same specific speed and flow rate at a low specific speed was proposed. however, a high unsteady flow was observed inside the pump. In this study, to predict performance and clarify internal flow accurately, unsteady CFD was used to investigate pump performance and internal flow, including different hydraulic losses when the impeller rotates once rotation. The results show that pump performance can be estimated more accurately using unsteady CFD than using steady CFD. Moreover, the constant drop in total head with flow rate is owing to the hydraulic losses in the impeller, which exclude friction, growing in proportion to flow rate.