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To investigate the flow characteristics in front chamber and rear chamber in pump mode and pump as turbine mode, a 3D computational model of a centrifugal pump was established, including the front and rear chamber. Based on Realizable k-ε turbulence model, numerical calculations of incompressible flow were carried out for internal viscous flow in two operating modes. Further analysis was conducted on the flow stability and hydraulic losses under two modes using energy gradient theory and entropy production theory. The numerical simulation results are within reasonable error compared to the experimental results in pump operation mode, which ensures the reliability of the numerical calculation method. The results indicate that the volumetric efficiency in both two modes is on an upward trend with increasing flow, but the volumetric efficiency of the pump mode is more significantly affected by changes in flow; the distribution patterns of dimensionless circumferential velocity and dimensionless radial velocity in the front and rear chambers under two operating modes are similar, but the distribution pattern of dimensionless radial velocity in the front chamber in turbine mode is significantly different from other operating conditions; flow instability is most likely to occur at the outlet of impeller, and the energy loss in clearance of wear-rings is greater than that in the pump chamber. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of the self-priming pump in the outdoor emergency rescue mobile pump truck, this paper took the key energy conversion component-impeller as the target and used the orthogonal experimental design method to optimize its hydraulic performance. Firstly the numerical calculations were compared with the experimental results to confirm the reliability of the calculation method. Then, L9 (34) orthogonal design was applied to investigate the influence of the impeller diameter, the blade outlet width, the blade wrap angle and the number of blades on the hydraulic performance of the self-priming pump. Through range analysis, the order of influence of each influencing factor on the head and efficiency of the self-priming pump was determined, and finally obtained the optimal parameter combination scheme. The results show that the optimized self-priming pump exceeds the head of the prototype pump at all flow conditions, and the efficiency curve at high flow conditions is significantly improved and has a wide high efficiency zone. [ABSTRACT FROM AUTHOR]