“Using Rotordynamics to Solve Serious Machinery Vibration Problems,”
M. E. Leader, 2009.


Seven case histories show how applying lateral and torsional rotordynamics analyses can solve serious machinery problems. In the first lateral case history a centrifugal compressor rotor critical speed is located exactly on operating speed. New bearings are designed that are significantly softer and the rotor mass is increased by one-third. These two modifications reduce the critical speed well below operating speed and greatly reduce the sensitivity to imbalance. In the second lateral case history a gas turbine is unstable with very high subsynchronous vibration. A special hybrid 3-pad dual pressure dam bearing is designed that is much more stable and less sensitive to clearance changes than the original 3-lobe bearings. In the last lateral case history a damper bearing is applied to a steam turbine rotor in order to decrease the effective bearing stiffness and allow for the damping to control the critical speed. Four torsional case histories explore ways to solve torsional vibration problems through proper design and system modifications.


Bearings; Critical Speeds; Damping; Design; Fatigue; Forced Response; Instabilities; Modeling; Properties; Rotors; Squeeze Film; Stability; Stress; Torsional; Vibration