Numerical Study of Pressure Fluctuations Caused by Impeller-Diffuser Interaction in a Diffuser Pump Stage

Two-dimensional and three-dimensional, unsteady state Reynolds-averaged Navier-Stokes (RANS) equations with standard k-ε turbulence models were solved within an entire stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes. A complete solution of transient flows due to the interaction between components in the whole pump without approximating the blade count ratio of impeller to diffuser was obtained by employing an Arbitrary Sliding Mesh. The unsteady numerical results were compared with experimental data and values calculated by the singularity method. As a result of the present study, the Navier-Stokes code with the k-ε model is found to be capable of predicting pressure fluctuations in the diffuser. Furthermore, extensive numerical studies identified sources contributing to the pressure fluctuations in the diffuser, and helped to understand the mechanism of impeller-diffuser interactions in the diffuser pump.