Reduced Shaft Stiffness Lowers Running-Speed Bearing Loads And Vibration In A Single Stage Compressor.
Abstract
Turbomachines that run well above their fundamental lateral critical speeds (super-resonant), and are not heavily influenced by higher vibrational modes, can often benefit from reductions in shaft stiffness to lower the running-speed bearing loads and vibration. This is because an unbalanced rotor running in the super-resonant regime tends to orbit eccentrically about its offset center of gravity, causing high bearing loads if the shaft is rigid. A more flexible shaft can deflect and reduce the dynamic force transmitted into the bearings, resulting in better bearing life and lower system vibration. In many cases, this can be done without lowering the damping enough to adversely affect the rotordynamic stability and unbalance response characteristics of the machine. A case study is presented in which a single-stage overhung compressor was modified to a smaller shaft diameter, yielding a beneficial 48 percent reduction in the computed bearing dynamic loads at running speed that improved bearing life and lowered the operating vibration levels.
Description
LecturePg. 33-44
Subject
TurbomachinesCollections
Citation
Armentrout, Richard W.; Wilson, Gerald E. (1993). Reduced Shaft Stiffness Lowers Running-Speed Bearing Loads And Vibration In A Single Stage Compressor.. Texas A&M University. Turbomachinery Laboratories. Available electronically from https : / /hdl .handle .net /1969 .1 /163517.