Engineering topics

Wachel, J. C.

Publications and source records attributed to Wachel, J. C..

3 records

NASA NTRS1984

Experiences with nonsynchronous forced vibration in centrifugal compressors

The high subsynchronous vibrations which are often forced vibrations caused by flow instabilities, such as stage stall were examined. Modifications to improve the rotor stability by changing the bearings or seals have little effects on the subsynchronous vibrations. Understanding of the differences between forced vibrations and self excited vibrations to properly diagnose the problem and to correct it, is recommended. A list of characteristics of the two types of subsynchronous vibration is presented.

Smith, D. R.↗

NASA NTRS1982

Rotordynamic instability field problems

Vibration data obtained during several rotor instability investigations is presented to illustrate the effect of changes in system parameters on overall rotor stability. The data includes the effects of bearing and seal changes as well as those due to variations in speed and pressure ratio. Field Problems indicate that the stability of rotors is often highly sensitive to fairly minor variations in bearing and seal parameters. Measured field data is valuable in normalizing analytical computer models so that effective solutions can be obtained.

Wachel, J. C.↗

NASA NTRS1980

Field verification of lateral-torsional coupling effects on rotor instabilities in centrifugal compressors

Lateral and torsional vibration data obtained on a centrifugal compressor train which had shaft instabilities and gear failures is examined. 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 gear boxes can reduce stability margins if energy is transmitted either laterally or torsionally to the compressors. The lateral and torsional coupling mechanisms of shaft systems is discussed. The coupling mechanisms in a large industrial compressor train are documented and the potential effect on rotor stability is demonstrated. Guidelines are set forth to eliminate these potential problems by minimizing the interaction of torsional and lateral responses and their effect on rotor stability.

Wachel, J. C.↗