Multi-stage pump vibration caused by excessive wear ring clearance, Improper balancing, rotating stall

Abstract

Generally, the centrifugal pump vibration caused by mis-alignment, unbalance or bearing failure. But, I have seen two abnormal vibration phenomena in a multi-stage high pressure pump which has 13th stage impeller.First issue is high vibration problem due to excessive clearance of wear ring and balancing issue. Second one is sub-synchronous vibration due to rotating stall at the inlet of diffuser. The root cause was figured out based on rotor dynamic, CFD(computational fluid dynamics) analysis and shop test of pump manufacturer. This paper will show the detail vibration phenomena, root cause analysis result and the countermeasure.