Investigation of the hydraulic design for a high-performance centrifugal pump

Abstract

We investigated the hydraulic design in terms of high efficiency and good cavitation performance of centrifugal pumps for water supplies. The subject of the investigation was the centrifugal pump, which consists of a suction bend, impeller, diffuser, and discharge volute. The investigation was basically conducted using computational fluid dynamics (CFD) with design of experiments (DOE) and an optimization technique. The suction bend design was implemented first to obtain a uniform flow at the impeller inlet to provide good cavitation performance. We investigated the sensitivity of each parameter value comprising the suction bend configuration for obtaining uniform flow using a parameter design technique with DOE and CFD analyses. The key parameters that enable a better flow field were estimated efficiently and the values of the parameters were adjusted to obtain the optimized configuration. On the other hand, to achieve high performance of the impeller and diffuser shape, the effect of the configuration parameter values on hydraulic loss was also examined using the parameter design based on CFD and a multi-objective optimization technique. The investigation for obtaining a shape achieving high hydraulic efficiency was made practical by taking into account the trade-off of performance characteristics, i.e., performance instability at a low flow rate and gradient of the head curve. When predicting hydraulic performance, it is important to investigate the interaction of flow between the impeller and diffuser to accurately simulate the flow field. The combined analysis of the impeller and diffuser, therefore, was implemented using unsteady flow simulation, and the results were applied to the parameter design using an optimization technique. Finally, the unsteady flow calculation of a complete pump was carried out to confirm the appropriateness of the hydraulic design. The hydraulic performance of the pump was also confirmed using a model pump test. As the result of these investigations, the hydraulic shape of a high-efficiency and high-cavitation centrifugal pump was developed.