Volute is an important hydraulic part of centrifugal pump, hydraulic loss within pump volute takes up a large part of total hydraulic loss within pump, thus appropriate design of pump volute has significant meaning to centrifugal pump performance. In this paper, numerical method was adopted to investigate volute main geometric parameters, including volute throat area, volute cross-section shape, design rule of spiral development area, and radial gap between impeller and volute tongue to pump performance. A design method of high-efficiency pump volute is developed through the influence of volute main geometric parameters to pump performance. This paper could provide theoretical guidance to high-efficiency pump volute design.

To improve the hydraulic performance in an ultra-low specific speed magnetic drive pump, optimized design of impeller based on orthogonal test was carried out. Blades number Z, bias angle in peripheral direction of splitter blades θ s , inlet diameter of splitter blades D si , and deflection angle of splitter blades α were selected as the main factors in orthogonal test. The credibility of the numerical simulation was verified by prototype experiments. Two optimized impellers were designed through the analysis of orthogonal test data. The internal flow field, pressure fluctuation, and radial force were analyzed and compared between optimized impellers and original impeller. The results reveal that impeller 7 (Z = 5, θ s = 0.4θ, D si = 0.75D 2 , α = 0 • ) could increase the head and efficiency, compared to the original impeller, by 2.68% and 4.82%, respectively. Impeller 10 (Z = 5, θ s = 0.4θ, D si = 0.55D 2 , α = 0 • ) reduced the head by 0.33% and increased the efficiency by 8.24%. At design flow rate condition, the internal flow of impeller 10 was the most stable. Peak-to-peak values of pressure fluctuation at the volute tongues of impeller 7 and impeller 10 were smaller than those of the original impeller at different flow rate conditions (0.6 Q d , 1.0 Q d and 1.5 Q d ). Radial force distribution of impeller 10 was the most uniform, and the radial force variance of impeller 10 was the smallest.Energies 2019, 12, 4767 2 of 21 Shigemitsu T. et al. [10,11] improved the design of a small centrifugal pump in the form of adding splitter blades. It was found that the flow near the impeller outlet became uniform after the splitter blades were used, while the efficiency of the volute increased and the vortex loss decreased.Yuan [12][13][14] discussed the principle and results of adding splitter blades based on the real flow in centrifugal pumps, the analysis results indicated that the splitter blades that deviated toward the suction surface of ordinary blades improved pump head and efficiency, adding splitter blades in the impeller moved the high efficiency point of the pump to the direction of large flow rate, and adding splitter blades in a screw-type centrifugal pump could decrease the radial forces on the impeller, but also decrease oscillations in volute as well. The influence of blade number was not considered in the analysis.Zhang [15,16] investigated the influences of different positions of splitter blades on the performance of a centrifugal pump, two different splitter blade schemes were proposed: One located in the middle of the channel and the other having a deviation angle to the suction side of the long blade. The results showed that adding splitter blades can improve the tangential component distribution of absolute velocity at impeller outlet, and the streamline has a better consistency with the blades shape when splitter blades deviated to the long blade, which decreases energy loss.Gu [17] and Cui [18] studied the effects of splitter blades on the performance and internal flow of low specific speed ce...

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