The necessary conditions for backward whirling motion of a Jeffcott rotor supported in identical hydrodynamic journal bearings are investigated in this paper. Backward whirling motion of the rotor centre is shown to occur if and only if the load parameter is greater than a limiting value corresponding to the flexibility parameter. In spite of the backward whirling motion of the rotor centre, the journal centre is shown to orbit only in the forward sense. © 1986, Academic Press Inc. (London) Limited. All rights reserved.

Natrajan Ganesan

Hydrodynamic bearing

BEARINGS - JOURNAL

BACKWARD WHIRLING MOTION

FLEXIBLE ROTOR

HYDRODYNAMIC JOURNAL BEARINGS

ROTORS

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IIT Madras

Conditions for backward whirling motion of a flexible rotor supported on hydrodynamic journal bearings

Journal of Sound and Vibration

This investigation is an attempt to provide information on the design of journal bearings for use in high speed rotating machinery to minimize the energy dissipation due to the out-of-balance of the flexible rotor. The results are presented in the form of design charts for full journal bearings, where the dissipation coefficient has to be selected to be as small as possible at the operating speed and at the critical speed. © 1986.

Wear

The dissipation coefficient and its application to flexible rotor-bearing system design

The well-known solutions for the pressure distribution in the lubricating film of a hydrodynamic journal bearing, satisfying the Reynolds boundary conditions, show a sudden change in the pressure gradient at the position of maximum film thickness, which is possible only if the lubricant is supplied precisely at this location. Since the pressure develops smoothly because of hydrodynamic action, a correction in the boundary conditions is applied and a modified solution for the pressure distribution is obtained. The stiffness and damping characteristics of a finite hydrodynamic journal bearing using the new boundary conditions are compared with the wellknown characteristics incorporating the Reynolds boundary conditions. There is a significant change in the dynamic characteristics particularly at low values of the eccentricity ratio which can influence the characteristics of rotor-bearing systems. © 1986.

The effect of modified inlet boundary conditions on the stiffness and damping characteristics of finite hydrodynamic journal bearings

Using the Reiner-Philippoff shear stress-shear strain rate relation a modified form of Reynolds equation is derived for a non-Newtonian (shear thinning as well as shear thickening) lubricant under conventional hydrodynamic lubrication approximations. A finite difference iteration scheme with successive over-relaxation incorporating Reynolds boundary conditions is used to obtain the pressure distribution of a cylindrical journal bearing. Steady state performance characteristics such as load capacity, friction and flow rate are obtained for various values of non-linear parameters. The results presented in dimensionless form and applicable to shear-thinning as well as shear-thickening lubricants are compared with established results for New-tonian lubricants. © 1979.

The steady state performance of a hydrodynamic journal bearing with a non-newtonian lubricant

The well-known solutions for the pressure distribution in the lubricating film of a hydrodynamic journal bearing, satisfying the Reynolds boundary conditions, show a sudden change in the pressure gradient at the position of maximum film thickness, which is possible only if the lubricant is added precisely at this position. Since the pressure develops smoothly because of hydrodynamic action, a correction in the Reynolds boundary conditions is proposed and a new solution for the pressure distribution is obtained. The steady state characteristics of a hydrodynamic journal bearing using the new boundary conditions are compared with the well-known characteristics using the Reynolds boundary conditions. © 1983.

Journal	Journal of Sound and Vibration
Publisher	Academic Press
ISSN	0022460x
Open Access	No