| Centrifugal pump is a commonly hydraulic machine, whose inner flow has direct influence on pump's performance and is a considered problem by the pump designers. with the phenomena of dropping flow, backflow and secondary flow effected by circulation and surface curvature, the centrifugal pump's inner flow is very complicated 3d flow . Therefore, the centrifugal pump inner flow is one of the difficult problems both in testing research and numeric computation .In the 1950s, some experts and scholars tried to use numeric computation method to predict the blade's inner flow. But it is thought that the mature pump inner flow numeric computation was started and then developed rapidly after the "two relative flow surface" (the S1 and S2) theory presented by professor Wuzhonghua. From then on, many domestic scholars have made much research on the numeric simulation of the centrifugal pump inner 3D turbulent, and they have made some progress, which were yet short of enough validation through experiment. In recent years, with the rapid development of the computer technology, CFD (computational fluids dynamics) develops rapidly, and many commercial computation softwares are applied widely. Some softwares have been used to compute the centrifugal pump inflow. Through the numeric simulation of the centrifugal pump inner flow by CFD, the distribution of the velocity and pressure in the pump are conducted to impeller design and hydraulic performance prediction, which has become one of the important modern pump design method.In this paper, based on the Navier-Stokes equation and the k- turbulent model, the numerical simulation of the 3D turbulent flow in a centrifugal impeller, of which specific speed is 93. The distribution of the velocity and pressure in the blade-to-blade passage are presented at the design and off-design operating conditions. The simulation results were verifiable with the results measured by PIV. This study can be very helpful to improve and optimize the impeller design.
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