The vibration of centrifugal pumps, running at both best efficiencypoint (BEP) and at low flow, is of interest to both pumpdesigners and users. This vibration is responsible for the poor seal and bearing life and reduced mean time between failure (MTBF).The cause of vane pass vibration and multiples of this areexplained in this paper. The causes of low flow vibrations are alsoexplored. The paper presents a methodology to limit the vibrationpotential of a machine running at BEP and also to limit the onsetof backflow recirculation.Two practical examples are included that demonstrate how thisdesign technique has been successfully applied to poorly performingmachines to successfully reduce their vibration levels.To assess the vibration level of a machine operating at BEP is aneasy process involving analysis on the impeller only. To assess thevibration potential at low flow from only computational fluiddynamics analysis is a lengthy process that, while informative, isless appropriate than the empirical methods proposed by Fraser(1981) and Palgrave (1985).
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