Internal Rotor Friction Induced Instability in High-Speed Rotating Machinery

Walton, James F., and Martin, Michael, “Internal Rotor Friction Induced Instability in High-Speed Rotating Machinery,” Presented at 14th Biennial Conference on Mechanical Vibration and Noise, September 19-22, 1993, Albuquerque, New Mexico, DE-Vol. 60 Vibrations of Rotating Systems, pp 297-305

Results of a program to investigate internal rotor friction destabilizing effects are presented. Internal-friction-producing joints were shown to excite the rotor system first natural frequency, when operating either below or above the first critical speed. The analytical models used to predict the subsynchronous instability were also confirmed. The axial spline joint demonstrated the most severe subsynchronous instability. The interference fit joint also caused subsynchronous vibrations at the first natural frequency but these were bounded and generally smaller than the synchronous vibrations. Comparison of data from the two test joints showed that supersynchronous vibration amplitudes at the first natural frequency were generally larger for the interference fit joint than for the axial spline joint. The effects of changes in imbalance levels and side loads were not distinguishable during testing because amplitude-limiting bumpers were required to restrict orbits.

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