Theoretical Study of Pressure Fluctuations at Downstream of a Diffuser Pump Impeller. Analysis of Unsteady Flow Due to Interaction between Impeller Blades and Guide Vanes/Volute Casing.

Abstract

An analytical method was proposed to calculate the unsteady flow induced by the interaction between impeller blades and diffuser vanes/volute casing in a diffuser pump. The singularity method was used for the analysis, and the unsteady flow in the diffuser as well as the volute casing is assumed to be induced by four kinds of unsteady singularities distributed on the impeller blades, diffuser vanes, volute casing wall and free vortices shed from diffuser vanes. The calculated unsteady pressures in the diffuser and volute casing agree well with the measured ones. Calculated results show that the volute casing has little effect on unsteady flow in the test diffuser.