Investigation of the volute effect on performance of a centrifugal-pump impeller with high-fidelity simulations

In this work, the Delayed eXtra-LES model is assessed for the simulation of the flow through a centrifugal pump, consisting of impeller, diffuser, and volute, both at design and off-design conditions. The results of the simulations of the impeller and pump with low- and high-fidelity models are compared with experiments and other numerical results available in literature, to demonstrate the effectiveness in modeling complex flow phenomena in centrifugal pumps with a good compromise between fidelity and computational cost of the Delayed eXtra-LES model. A critical aspect is represented by the choice of the filter width,as different filter widths lead to different results. Furthermore, the simulations with the high-fidelity model of the impeller and complete pump demonstrated the influence of the volute on the flow field. The steady “two-channel” stall phenomenon with an alteration of stall and non-stall channels appears at the off-design conditions, both without and with the volute. The tongue of the volute as well as different turbulence models, Sub-Grid Scale models, and filter widths lead to differences in the dimensions and location of vortexes.