Nonlinear dynamic analysis of a flexible rotor supported by micropolar fluid film journal bearings

This paper studies the nonlinear dynamic analysis of a flexible rotor supported by externally pressurized porous gas journal bearings. A time-dependent mathematical model for externally pressurized porous gas journal bearings is presented. The finite difference method and the Successive Over Relation (S.O.R.) method are employed to solve the modified Reynolds’ equation. The system state trajectory, Poincare´ maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and quasi-periodic response of the rotor and journal center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and bearing number. The results of this study contribute to a further understanding of the nonlinear dynamics of gas-lubricated, externally pressurized, porous rotor-bearing systems.

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An optimised short bearing theory for nonlinear dynamic analysis of turbulent journal bearings

European Journal of Mechanics - A/Solids ◽

10.1016/s0997-7538(00)00139-x ◽

2000 ◽

Vol 19 (1) ◽

pp. 151-177 ◽

Cited By ~ 26

Author(s):

M. Lahmar ◽

A. Haddad ◽

D. Nicolas

Keyword(s):

Dynamic Analysis ◽

Nonlinear Dynamic ◽

Nonlinear Dynamic Analysis ◽

Journal Bearings

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Dynamic Analysis of a Flexible Rotor Supported on Two Turbulent Model Journal Bearings with Micropolar Fluid Lubrication

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.1386 ◽

2014 ◽

Vol 592-594 ◽

pp. 1386-1390

Author(s):

Sushant Bhatia ◽

Jaideep Gupta

Keyword(s):

Dynamic Analysis ◽

Micropolar Fluid ◽

Reynolds Equation ◽

Journal Bearings ◽

Flexible Rotor ◽

Wide Range ◽

Dimensional Parameters ◽

Rotor Center ◽

Nonsynchronous Vibrations ◽

Tangential Directions

This paper presents the complex dynamic analysis of a flexible rotor–bearing system supported by two turbulent micropolar fluid film journal bearings under nonlinear suspension. The Modified Reynolds equation based on the assumptions of turbulent flow and the micropolar parameters has been considered. The system considers Short bearing approximation to simplify the numerical computations. The pressure distribution thus obtained is used to find out the resulting forces about the journal center in the radial and tangential directions. The Non-dimensional dynamic equations are derived considering appropriate non dimensional parameters and solved using MATLAB for a wide range of non-dimensional speed ratios. Plots of the journal center trajectories and rotor center trajectories are obtained. The results show that the system undergoes undesirable nonsynchronous vibrations due to bearing center displacement. Micropolar fluid is found to stabilize the system even when the flow of the system becomes turbulent. The study presented enhances the understanding of the nonlinear dynamics of turbulent journal bearings with respect to dimensionless parameters.

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