| dc.description.abstract | Rotating disk and blade fatigue failures are usually a low percentage of failures in most machinery types, but other than coupling / shaft end failures remain some of the most problematic for extensive repairs. High-cycle fatigue failures of rotating disks and blades are not common in most machinery types, but when they occur, they require extensive repairs and resolution can be problematic. This paper is an update of the tutorial given at the 2004 Turbomachinery Symposium focusing on high-cycle fatigue failures in steam turbines, centrifugal and axial gas compressors in refineries and process plants. The failure theories and many of the descriptions for cases given in 2004 have been updated to include blade resonance concerns for potential flow as well as vane and blade wake effects. Disk vibratory modes can be of concern in many machines, but of little concern in others as will be explained. In addition, vibratory modes are included where blades are coupled via communication with the main disk. Over the past decade, fluid-structure-interaction computational methods and modal testing have improved and have been applied to failure theories and problem resolution in the given cases. There is also added information on the effects of mistuning blades and disks, some beneficial and some with serious concerns for increased resonant amplification. Finally, knowledge about acoustic pressure pulsation excitation, particularly for centrifugal impellers at rotating blade passing frequency, has been greatly expanded. A review of acoustics calculations for failure prevention, mainly for high-pressure applications is covered here. | en |
