Development of a CFD Procedure for the Axial Thrust Evaluation in Multistage Centrifugal Pumps

One of the most challenging aspects in horizontal pumps design is represented by the evaluation of the axial thrust acting on the rotating shaft. The thrust is affected by pump characteristics, working conditions and internal pressure fields. Solving this problem is simple for single stage pumps while several complications arise for multistage pumps even in partially self-balancing opposite impeller configuration. Therefore a systematic approach to the axial thrust evaluation for a multistage horizontal centrifugal pump has been assessed and validated. The method consists in CFD simulation of each single pump component to obtain correlations which express the axial thrust as a function of the working conditions. The global axial thrust is finally calculated as balance of the forces acting on each stage. The numerical procedure will be explained and its main results shown and discussed in the present paper.