The centrifugal pump is applied widely in many fields with significant advance made in the understanding of the key technical phenomena related to its running at constant rotating speed; and more and more studies are concerned about its transient operation, because its design not only has close relation with operation parameters under constant speed but also those under the startup and shutoff period, especial the pressure fluctuation and hydraulic performance. In order to investigate the transient characteristics during the startup period of a centrifugal pump, the experiment is carried out and numerical simulation is made. The experiment was conducted on the POL's pump test rig, and the rapid data acquiring program was added in order to get the torque, pressure, and rotating speed during the startup period. Based on the torque equations induced in the paper, numerical simulation is made with the Large Eddy Simulation (LES) method and UDFs (User Defined Functions). Comparison of pump heads and rotating speed between simulation and experimental results shows that they are in good agreement, indicating that the dynamic characteristics of the centrifugal pump can be predicted accurate comparatively through simulation with LES method during its startup process. In addition, the pressure distribution of half height of vane on the cross section at different time was obtained, showing that the pressure increases with time going.
