Based on the whole and nonwhole flow domain methods, the influence of flow domain on the numerical results in centrifugal pumps was investigated by calculating threedimensional steady incompressible turbulent flows. The standard k-ε turbulence model and virtual block technology were also adopted. The internal flow fields and hydraulic performance of five centrifugal pumps with different specific speeds were calculated at the design conditions. Also, the hydraulic performance obtained was compared with the test. It is observed that the influence of flow domain is remarkable. The whole flow domain method shows a higher accuracy rather than the nonwhole flow domain one, for example, the prediction accuracies in head and efficiency are improved by 1.54% and 1.67%, respectively. The static pressure distributions in the impellers obtained by the two methods are basically the same, but those in the volutes are significantly different. The velocity profile in the gap between impeller and volute is layered for the whole domain method. However, it is triangular for the nonwhole domain one. The secondary flow pattern within the crosssections of volute is not completely symmetry. It is believed that the flows in the wearingring gap and the chamber between the impeller and the pump casing, which have been considered in the whole flow domain method, affect the development of that secondary flow.
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