A Novel Variable Impedance Hydrodynamic Oil-Film Bearing: Part 1: Theoretical Modelling

Abstract

A novel bearing design is presented. The bearing consists of a partial arc bearing into which two recesses are machined. Attached to the two recesses, via remote-controlled valves, are two accumulators. The ability to be able to open and close the valves gives the new bearing design four independent operating modes. Steady state operating characteristics for the bearing were predicted using a finite difference solution to Reynolds' equation. A new mathematical model is proposed for the recess boundary. The model is based on flow continuity and enables a finite difference node to be positioned on the recess boundary. It is demonstrated that the theoretical model proposed predicts steady state characteristics which agree favourably with previously published work and with experimental data. The model was further utilized, in a pressure perturbation algorithm, to obtain predictions of the bearing's dynamic operating characteristics. It is demonstrated that by switching the valves from open to closed, or vice versa, the bearing's characteristics can be altered in situ. It is also demonstrated that the inclusion of the recesses and accumulators has little effect on the steady state characteristics when compared to those of a conventional partial arc bearing.

It is suggested that the bearing design proposed in this paper has major advantages to offer the rotating machine designer. Use of the bearing enables the operator to vary support characteristics without major re-machining. Furthermore, support characteristics may be varied in situ, without significant cost penalties and with little additional maintenance overheads.

Keywords

hydrodynamic oil-film bearing accumulators finite difference solution recess boundary mathematical model pressure perturbation algorithm

Get full access to this article

View all access options for this article.

References

Roach

M. P.

Vibration control of rotating machinery using variable dynamic stiffness hydrostatic squeeze-films. PhD thesis, Staffordshire University, 1990.

Larsonneur

Siegwart

Traxler

Active magnetic bearing control strategies for solving vibration problems in industrial rotor systems. Proceedings of IMechE Conference on Vibrations in rotating machinery, September 1992, paper C432/088, pp. 83–90 (Mechanical Engineering Publications, London).

Knopse

C. R.

Humphries

R. R.

Maslen

E. H.

Allaire

P. E.

Active balancing of a high speed rotor in magnetic bearings. Proceedings of Rotordynamics '92, April 1992, pp. 19–26 (Springer-Verlag, New York).

Boroomand

Variable impedance journal bearings for rotorbearing systems. PhD thesis, Staffordshire University, 1990.

Goodwin

M. J.

Boroomand

Hooke

C. J.

Variable impedance hydrodynamic journal bearings for controlling flexible rotor vibrations. Rotating machinery dynamics. Proceedings of the 1989 ASME Design Conference on Mechanical vibration and noise, Canada, 1989.

Cameron

Basic lubrication theory, 1971, Longman Publishing, London).

Bannister

Theoretical and experimental investigation illustrating the influence of non-linearity and misalignment on the eight oil film force coefficients. Proceedings of IMechE Conference on Vibrations in rotating machinery, 1976, paper C219/76, pp. 271–278 (Mechanical Engineering Publications, London).

Ogrodnik

P. J.

Operation of rotor-bearing systems subject to dynamic conical misalignment. PhD thesis, Staffordshire University, 1989.

Raymondi

A. A.

Boyd

A solution for the finite journal bearing and its application to analysis and design. Trans. ASLE, 1958, 1(1), 159–209.

10.

Fang

Calculation and measurement of the eight oil film stiffness and damping coefficients for a variable impedance hydrodynamic bearing. PhD thesis, Staffordshire University, 1994.

11.

Lund

J. W.

Thomsen

K. K.

A calculation method and data for the dynamic coefficients of oil-lubricated journal bearings. In Topics in fluid film bearing and rotor system design and optimization, 1978, pp. 1–28 (American Society of Mechanical Engineers, New York).