Abstract:According to the structure characteristics of impeller of a screw centrifugal pump, the streamwise evolutionary pattern of blade pitch was analyzed by applying the theory of relative velocity ratio of liquidsolid twophase flow model for an impeller pump, and then a parametric equation for variablepitch was deduced. For the given hydraulic performance parameters and a volume fraction of the solid phase at the design point, a smooth, threedimensional blade profile could be established through the parametric equations.The water performance of a screw centrifugal pump whose blades were designed in that way was measured, and accordingly its performances of liquidsolid twophase flow were estimated numerically at three volume fractions of 5%, 15% and 25% with a CFD code, respectively. The results show that the pump efficiency for transporting solidliquid twophase medium is better than for transporting water. At the design point, for a given volume fraction of solid phase, the pump efficiency is increased by 8.5%; however, when the volume fraction is different from that given value, the pump efficiency is reduced.Compared with water single phase flow, the pump head of liquidsolid twophase flow is not only decreased, and but also lowered gradually with increasing solidphase concentration.
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