A Consideration of Damping in Rotors Supported by Tilting-Pad Bearings

  • M. F. White
Conference paper

Abstract

Tilting-pad journal bearings are often used in high performance machinery operating at speeds above the first critical speed, in order to improve bearing stability. In many cases such machinery may still be prone to subsynchronous or unstable vibration problems. The influence of the dynamic characteristics of the tilting-pad bearings on the response of the complete rotor system is therefore of great importance. This paper is primarily concerned with the damping provided by such bearings. A number of factors are considered including frequency dependence of the dynamic coefficients, influence of pad support flexibility, and a simple method for evaluation of effective damping required to maintain rotor stability.

Keywords

Acoustics 

Nomenclature

B

Cross coupling stiffness

C

Damping

Ci

Bearing damping

Cp

Pad clearance (Rp - R)

Cs

Damping to maintain stability

D

Journal diameter

E

Modulus of elasticity

I

Moment of area/pad inertia

k

Pad stiffness

K

Stiffness

ω

Rotational speed (rad/s)

Kp

Pivot stiffness

F

Force

m

Mass

N

Rotational speed (Hz)

R

Journal radius

Rp

Pad radius

W

Load

δ

Pad rotation angle Dynamic viscosity

ωn

Critical speed (rad/s)

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    W. Diewald and R. Nordmann, “Dynamic Analysis of Centrifugal Pump Rotors with Fluid-Mechanical Interactions”, 11th Biennial Conference on Mechanical Vibrations and Noise, Boston/USA 1987.Google Scholar
  2. [2]
    F.J. Dietzen and R. Nordmann, “Calculating Rotordynamic Coefficients of Seals by Finite Difference Techniques”, Journal of Tribology, 1987, Vol. 109, pp. 388–394.CrossRefGoogle Scholar
  3. [3]
    D. Weber, R. Cardinali and R. Nordmann, “A Modal Substructure Technique for the Nonlinear Dynamic Simulation of Hydroelectric Machines”, International Conference on Mechanics of Solids and Structures, Nanyang Technological University, Singapore 1991.Google Scholar
  4. [4]
    R. Gasch and R. Knothe, Strukturdynamik, Vol. II, Springer Verlag, New York, London, Paris, Tokyo, 1989.CrossRefMATHGoogle Scholar
  5. [5]
    G.B. Dubois and F.W.- Ocvirk, “Analytical Derivation and Experimental Evaluation of Short-Bearing Approximation for Full Journal Bearings”, National Advisory Committee for Aeronautics, Report 1157, 1953.Google Scholar
  6. [6]
    G.L. Falkenhagen, E.J. Gunter, F.T. Schuller, “Stability and Transient Motion of a Vertical Three-Lobe Bearing System”, 1971. ASME paper No 71-VIB-76.Google Scholar
  7. [7]
    H. Springer, “Zur Berechnung hydrodynamischer Lager mit Hilfe von Tschebeyscheff-Polynomen”, Forschung im Ingenieurwesen, 1978, Vol. 4, pp. 126–134.CrossRefGoogle Scholar
  8. [8]
    R. Klump, “Ein Beitrag zur Theorie der Kippsegmentlager”, Diss. TH Karlsruhe 1975.Google Scholar
  9. [9]
    H.J. Merker, “Über den nichtlinearen Einfluß von Gleitlagern auf die Schwingungen von Rotoren”, Diss. Universität Darmstadt, 1981.Google Scholar
  10. [10]
    R. Cardinali, R. Nordmann, A. Sperber, “Dynamic Simulation of Nonlinear Models of Hydroelectric Machinery ”, submittet to Journal of Mechanical Systems and Signal-Processing. 1991.Google Scholar

Copyright information

© Springer-Verlag London Limited 1992

Authors and Affiliations

  • M. F. White
    • 1
  1. 1.Division of Marine EngineeringUniversity of TrondheimTrondheimNorway

Personalised recommendations