Rotating Component Modal Analysis and Resonance Avoidance Recommendations

Rotating blade and disk fatigue failures cause a fairly small percentage of machine shutdowns, but can require extensive repairs and downtime. This tutorial focuses on steam turbines, centrifugal compressors, and axial compressors primarily for refineries and process plants. For steam turbines, axial compressors, and openimpeller centrifugal compressors, the main concern is resonance giving blade rather than disk vibration. For covered impellers in centrifugal compressors disk modes are the main response for problems, albeit failures are much more rare. Reviews of methods are to give insight to design evaluation, calculation, and test procedures. Cases will be given where designs were suspect with high potential for cause of fatigue, with other cases due to minor resonance combined with either manufacturing defects, operation, and/or environment such as liquid ingestion and corrodants. For some cases, test data will be correlated with theories provided, while others will use references, some of which will be shown to perhaps require consideration of alternative probable causes. The material will utilize both proven concepts and cases for lessons learned.