HIGH EFFICIENCY AND LOW PRESSURE FLUCTUATION REDESIGN OF A CENTRIFUGAL PUMP BASED ON UNSTEADY CFD ANALYSES

In this study, a double volute centrifugal pump of relative low efficiency and high vibration was redesigned with the aid of unsteady CFD analyses. The local Euler head distribution (LEHD) representing the energy growth from the blade leading edge to trailing edge on s 1 stream surface in a viscous flow field was introduced to evaluate the flow on s1 stream surfaces from hub to shroud. To investigate the unsteady internal flow of the centrifugal pump, the unsteady Reynolds-averaged Navier-Stokes equations (URANS) were solved with realizable k-s turbulence model using the CFD code FLUENT. The impeller was redesigned with the same outlet diameter as prototype pump. A two-step-form LEHD was recommended to suppress flow separation and secondary flow encountered in the prototype impeller to improve the efficiency. The splitter was added to improve the hydraulic performance and reduce unsteady radial forces. The original double volute was substituted by a newly designed single volute. The hydraulic efficiency of the redesigned centrifugal pump is 89.2%, 3.2% higher than the prototype pump. The pressure fluctuation in volute is significantly reduced and the mean and max values of unsteady radial force are only 30% and 26.5% of the prototype pump.