Stability of a Rigid Rotor Supported on Rough Oil Journal Bearings

1990 ◽  
Vol 112 (1) ◽  
pp. 73-77 ◽  
Author(s):  
B. C. Majumdar ◽  
M. K. Ghosh
Keyword(s):  
Surface Roughness ◽  
Journal Bearings ◽  
Variance Ratio ◽  
Rigid Rotor ◽  
Roughness Parameters ◽  
Roughness Effect ◽  
Composite Surface ◽  
The Stability ◽  
Orientation Pattern ◽  
Rigid Rotors

This investigation deals with the stability of rigid rotors supported on finite rough oil journal bearings using perturbation method. The effect of various surface roughness parameters, viz., composite surface roughness, roughness orientation pattern and variance ratio on the stability has been studied. In general, surface roughness effect when incorporated into the analysis does not show a significant change in the stability for surfaces having same roughness structure. However, the effect of variance ratio (i.e., surfaces having different roughness structure) on stability is quite marked.

Stability of Rough Journal Bearings Using Nonlinear Transient Method

1995 ◽  
Vol 117 (4) ◽  
pp. 691-695 ◽  
Author(s):  
J. Ramesh ◽  
B. C. Majumdar
Keyword(s):  
Surface Roughness ◽  
Journal Bearings ◽  
Variance Ratio ◽  
Transient Method ◽  
Roughness Parameters ◽  
Composite Surface ◽  
Nonlinear Transient ◽  
The Stability ◽  
Orientation Pattern ◽  
Rigid Rotors

The stability of rigid rotors supported on finite oil rough journal bearings has been investigated using nonlinear transient method. The effect of various surface roughness parameters, viz., composite surface roughness, roughness orientation pattern, variance ratio on the stability is presented in the form of journal center trajectories. Although the stability is affected marginally with the increase in composite roughness, the variation is quite significant when the shear flow factor comes into the picture.

Non-linear Transient Analysis of Submerged Oil Journal Bearings Considering Surface Roughness and Thermal Effects

1995 ◽  
Vol 209 (1) ◽  
pp. 53-61 ◽  
Author(s):  
J Ramesh ◽  
B C Majumdar ◽  
N S Rao
Keyword(s):  
Surface Roughness ◽  
Transient Analysis ◽  
Constant Load ◽  
Journal Bearings ◽  
Roughness Effects ◽  
Periodic Load ◽  
Composite Surface ◽  
Non Linear ◽  
The Stability ◽  
Rotating Load

A time-transient non-linear analysis has been carried out to study the influence of surface roughness and viscosity-temperature dependency on stability of a submerged oil journal bearing. The average Reynolds equation has been solved simultaneously along with the energy equation and heat-transfer equation in bush and shaft. The cavitation model, proposed by Kicinski along the lines of Jacobsson-Floberg theory, has been modified to account for the surface roughness effects. The effect of various surface roughness parameters, such as the composite surface roughness, roughness orientation pattern and variance ratio, on the stability has been studied. The non-linear transient analysis of submerged oil journal bearings under (a) a unidirectional constant load, (b) a unidirectional periodic load and (c) a variable rotating load is performed.

Comparison Between Linear and Nonlinear Transient Analysis Techniques to Find the Stability of a Rigid Rotor

1999 ◽  
Vol 121 (1) ◽  
pp. 198-201 ◽  
Author(s):  
Ram Turaga ◽  
A. S. Sekhar ◽  
B. C. Majumdar
Keyword(s):  
Transient Analysis ◽  
Stability Limit ◽  
Journal Bearings ◽  
Quantitative Comparison ◽  
Rigid Rotor ◽  
Analysis Techniques ◽  
Analysis Technique ◽  
Nonlinear Transient ◽  
Nonlinear Transient Analysis ◽  
The Stability

The subsynchronous whirl stability limit of a rigid rotor supported on two symmetrical finite journal bearings has been studied using the linearised perturbation method and the nonlinear transient analysis technique. A quantitative comparison for journal bearings with different l/d ratios has been provided.

Non-Linear Transient Stability Analysis of a Rigid Rotor Supported on Journal Bearings With Rectangular Dimples

2015 ◽  
Author(s):  
Ram Turaga
Keyword(s):  
Stability Analysis ◽  
Surface Texture ◽  
Transient Stability ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Pressure Curve ◽  
Rigid Rotor ◽  
Non Linear ◽  
The Stability ◽  
Transient Stability Analysis

The influence of deterministic surface texture on the sub-synchronous whirl stability of a rigid rotor has been studied. Non-linear transient stability analysis has been performed to study the stability of a rigid rotor supported on two symmetric journal bearings with a rectangular dimple of large aspect ratio. The surface texture parameters considered are dimple depth to minimum film thickness ratio and the location of the dimple on the bearing surface. Journal bearings of different Length to diameter ratios have been studied. The governing Reynolds equation for finite journal bearings with incompressible fluid has been solved using the Finite Element Method under isothermal conditions. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. When the dimple is located in the raising part of the pressure curve the positive rectangular dimple is seen to decrease the stability whereas the negative rectangular dimple is seen to improve the stability of the rigid rotor.

Stability Analysis of Two-Layered Finite Hydrodynamic Porous Journal Bearing Using Linear and Nonlinear Transient Method

2007 ◽  
Author(s):  
S. K. Kakoty ◽  
S. K. Laha ◽  
P. Mallik
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
System Stability ◽  
Rigid Rotor ◽  
Transient Method ◽  
Porous Bearing ◽  
Nonlinear Transient ◽  
Linear And Nonlinear ◽  
The Stability

A theoretical analysis has been carried out to determine the stability of rigid rotor supported on two symmetrical finite two-layered porous oil journal bearings. The stability curves have been drawn for different eccentricity ratios and Sommerfeld numbers. The effect of bearing feeding parameter, L/D ratio on the stability is also investigated. This paper also deals with a theoretical investigation of stability using a non-linear transient method. This analysis gives the journal centre locus and from this the system stability can be determined. With the help of graphics, several trajectories of the journal centre have been obtained for different operating conditions. Finally a comparison between single-layered porous bearing and the two-layered porous bearing is presented here.

Chaos of a Flexible Rotor in Journal Bearings

1995 ◽  
Author(s):  
R. D. Brown ◽  
G. Drummond
Keyword(s):  
Theoretical Models ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
Rigid Rotor ◽  
Flexible Rotor ◽  
Hydrodynamic Bearings ◽  
Stress Reversals ◽  
Oil Films ◽  
Rigid Rotors ◽  
Rotor Model

Abstract Nonlinear systems can give rise to chaotic behaviour, essentially unpredictable. Oil film forces arising from hydrodynamic bearings in rotating machinery can be extremely nonlinear under conditions of large unbalance. Chaotic response has been demonstrated in theoretical models of rigid rotors supported in hydrodynamic bearings. The behaviour of a rigid rotor can be extended by looking at a flexible rotor model supported on journal bearings and subject to large unbalance levels. The introduction of a flexible shaft yields chaotic regions which are less extensive than those obtained from a rigid rotor model. This is not surprising as the nonlinearity in the model is confined to the oil films at the end of the shaft. However if this level of unbalance is experienced in service then shaft fatigue could occur because of the sustained nature of the non-synchronous response and the effect of the resulting stress reversals.

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