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Right and Left-Hand Natural Modes of Industrial Rotating Machines. Model Study

  • R. Bigret
  • S. Vialard
  • P. Karajani
  • R. Chevalier
Conference paper
Part of the International Centre for Mechanical Sciences book series (CISM, volume 352)

Abstract

The rotors of rotating machines are guided by links. The matrixes representing links are, in general, not symmetrical. Right and left-hand natural modes differ. Left-hand modes are particularly used to define modal unbalances.

The high pressure rotor of a turbine generator of 1000 MW at 1500 rpm of a nuclear plant is here being studied. Three models are described; their first flexural natural pulsation, while on fixed supports, is equal to 1116 rpm, close to the first critical speed. The structure of the first two models is that of a De Laval-Jeffcott rotor, the third rotor concords with a high pressure rotor. For each of the models, two kinds of bearings have been teamed : cylindrical and 3 lobes.

Natural pulsations as well as right and left-hand modes are determined by literal formulas for the first model, by special software for the other two. Comparisons are set up between amplitudes and the phases of the right and left-hand natural modes; the differences are related to the assymetries of impedance matrixes.

The quality of the first two models, in reference to the concordant model, is shown through the comparison between the natural modes.

Keywords

Rotational Speed Amplitude Ratio Critical Speed Natural Mode Turbine Generator 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1. Ref. 1:
    Application of Modal Analysis to the balancing of Rotating Machines R. Bigret - 4th International Modal Analysis Congress (IMAC) - Los Angeles, USA - 1986.Google Scholar
  2. 2. Ref. 2:
    Modal Testing Theory of Rotor-Bearing Systems Yang-Gyu Jei, Young-ju Kim - Journal of Vibration and Acoustics - April 1993 - Vol. 115.Google Scholar
  3. 3. Ref. 3:
    Raideurs et Amortissements des Paliers Hydrodynamiques Les Memoires Techniques du CETIM - France - N 32 - December 1977.Google Scholar

Copyright information

© Springer-Verlag Wien 1994

Authors and Affiliations

  • R. Bigret
    • 1
  • S. Vialard
    • 1
  • P. Karajani
    • 1
  • R. Chevalier
    • 2
  1. 1.I.S.M.C.M.Saint OuenFrance
  2. 2.E.D.F. — D.E.R.ClamartFrance

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