Understanding of energy conversion and losses in a centrifugal pump impeller

As energy consumption saving becomes an urgent need in the contemporary world, the demand for improving pump energy efficiency is attracting increasing attention. This paper presents an extensive numerical investi-gation of energy transfer and dissipation in a centrifugal pump impeller, with the aim of elucidating the un-derlying mechanisms of loss and revealing the energy conversion processes in the impeller. The turbulent flows of the impeller are studied using very large eddy simulation under nominal flow rate and two part-load condi-tions. A new loss assessment model, which quantifies total loss by mean-flow viscous loss and turbulent loss, is proposed based on a detailed analysis of the budgets of the mean-flow kinetic energy and turbulent kinetic energy (TKE). Results show that the turbulent loss supplied by TKE production is the main part of the total loss in all investigated cases. The mean-flow viscous dissipation related loss decreases significantly under part-load conditions. Energy conversion processes and their relevance to the flow structures have been revealed by investigating the spatial distributions of TKE production, mean-flow viscous dissipation and turbulent dissipa-tion. Finally, the contributions of each subcomponent of the TKE production term to TKE production have been explored.