Paper No. 21
Field Verification of Lateral-Torsional Coupling Effects on Rotor Instabilities in Centrifugal Compressors
J. C. Wachel/F. R. Szenasi, NASA CP 2133, Rotordynamics Instability Problems in High-Performance Turbomachinery, Texas A&M University, May 1980, pp. 15-34.
Lateral and torsional vibration data were obtained on a centrifugal compressor train which had shaft instabilities and gear failures. The field data verifies that the stability of centrifugal compressors can be adversely affected by coincidence of torsional natural frequencies with lateral instability frequencies. The data also indicates that excitation energy from gearboxes can reduce stability margins if energy is transmitted either laterally or torsionally to the compressors. The lateral and torsional coupling mechanisms of shaft systems have been investigated both in theory and in laboratory models by other investigators. This paper documents these coupling mechanisms in a large industrial compressor train and demonstrates the potential effect on rotor stability. Guidelines are set forth to eliminate these potential problems by minimizing the interaction of torsional and lateral responses and their effect on rotor stability.