A computer-aided design system has been developed for hydraulic parts of pumps including impellers, bowl diffusers, volutes, and vaned return channels. The key technologies include three-dimensional (3-D) CAD modeling, automatic grid generation, CFD analysis, and a 3-D inverse design method. The design system is directly connected to a rapid prototyping production system and a flexible manufacturing system composed of a group of DNC machines. The use of this novel design system leads to a drastic reduction of the development time of pumps having high performance, high reliability, and innovative design concepts. The system structure and the design process of “Blade Design System” and “Channel Design System” are presented. Then the design examples are presented briefly based on the previous publications, which included a centrifugal impeller with suppressed secondary flows, a bowl diffuser with suppressed corner separation, a vaned return channel of a multistage pump, and a volute casing. The results of experimental validation, including flow fields measurements, were also presented and discussed briefly.

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New equations for hydraulic efficiency conversion from a model to a prototype centrifugal pump including mixed and axial flow types have been developed and proposed in this paper. In order to establish a set of conversion equations applicable for all type numbers of pumps, the following factors related to the conversion equations were examined. 1) The ratio of scalable loss to total hydraulic loss was examined by using CFD (Computational Fluid Dynamics) analysis. The ratio is related with the effect of actual complex velocity distributions in the flow passages in the impeller and diffuser/volute casing. 2) The conversion equation was constructed by two terms dealing with flow passages in two major hydrodynamic components, impeller and diffuse/volute separately, where contributions of each component to the efficiency step-up was expressed explicitly. 3) The friction coefficient ratio between a model and prototype pump was expressed in a simplified equation, applicable for both hydraulically-smooth and transitional surfaces. This expression was found to be useful to determine the relationship between equivalent machined surface roughness and uniform sand roughness, as the friction coefficient diagram expressed for uniform sand roughness is used for conversion of hydraulic losses between the model and prototype pumps. 4) The difference between the friction coefficients for decelerating flow and for a flat plate with uniform flow was examined by CFD analysis, and it was found that the friction coefficient for a flat plate can be used for the conversion without causing any substantial deviation.

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This paper described a reverse running double suction centrifugal pump turbine, which was newly designed and developed in order to adopt at a high fixed rotational speed 2980 [min−1] with high head H=245.6 [m]. New turbine model was developed by using CFD and its performance was validated by model test. There were a few studies about a reverse running pump turbine. However, a method of “Q-H performance adjustment” for the pump turbine is not clear. In order to reveal a method of Q-H performance adjustment of a turbine, CFD simulation and model test was carried out. The model test results showed that the performance of new turbine model fully satisfied Q-H requirement. And the results of steady CFD simulation were in good agreements with the model test results. Two possible methods to adjust the Q-H performance curve of a reverse running double suction centrifugal pump turbine were confirmed by model tests and CFD. The first method was modifying a throat sectional area of inlet spiral casing by cutting off a casing tongue. The model test result showed that this method moves the Q-H performance curve of turbine from high head to lower head at a constant capacity with very small efficiency drop at rated operating point. The result of CFD showed that, the Q-H performance change was obtained by the change in absolute tangential velocity at the runner inlet, which represents the inlet angular momentum, by the modification of throat sectional area. The second method was adjusting the runner outlet velocity triangle by modifying the runner blade trailing edge profile by under-filing or over-filing. The model test result proved that, the above modification of runner blade trailing edge profile is effective to control the Q-H performance curve of a reverse running pump turbine.