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.

Stability and Transient Characteristics of Four Multilobe Journal Bearing Configurations

1980 ◽  
Vol 102 (3) ◽  
pp. 291-298 ◽  
Author(s):  
D. F. Li ◽  
K. C. Choy ◽  
P. E. Allaire
Keyword(s):  
Transient Analysis ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Frequency Content ◽  
Stability Threshold ◽  
Fast Fourier Transform Analysis ◽  
Linearized Stability ◽  
Nonlinear Transient ◽  
The Stability

Multilobe journal bearings are often used to improve the stability response of rotating machinery. Such machines operate near the stability threshold of the bearing-rotor system. This work determines the linearized stability threshold of four multilobe journal bearings: elliptical, offset elliptical, three lobe, and four lobe. A nonlinear transient analysis of a rigid rotor in each of these bearings is carried out above and below the threshold speed. Shaft orbits and bearing forces are calculated. A numerical fast Fourier transform analysis is used to obtain the frequency content of the nonlinear orbit.

Stability of oil-lubricated externally pressurized two-layered porous journal bearings: A non-linear transient analysis

2003 ◽  
Vol 217 (3) ◽  
pp. 223-228 ◽  
Author(s):  
N Saha ◽  
B. C. Majumdar
Keyword(s):  
Transient Analysis ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
System Stability ◽  
Transient Method ◽  
Non Linear

The present study is an attempt to find the whirl instability of externally pressurized two-layered porous oil journal bearings using a non-linear transient method. This analysis gives the journal centre locus, from which the system stability can be ascertained. Several trajectories of the journal centre have been drawn for different operating conditions. It has been observed that a two-layered porous journal bearing gives higher stability than the conventional (single-layered) porous journal bearing.

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.

Stability of a Rigid Rotor Supported by Aerostatic Journal Bearings With Circular Slot Restrictors (On the Double-Row Admission Bearing)

1988 ◽  
Vol 110 (2) ◽  
pp. 228-234 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Anno ◽  
T. Ohashi
Keyword(s):  
Theoretical Analysis ◽  
Energy Loss ◽  
Point Source ◽  
Gas Flow ◽  
Journal Bearing ◽  
Rapid Change ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Double Row ◽  
The Stability

This paper discusses the stability of a rigid rotor supported by double-row admission journal bearings with circular slot restrictors. In the theoretical analysis, the energy loss at the outlet of the slot is taken into account because the gas flow is subject to a rapid change in direction, and here, the energy loss coefficient is determined experimentally. It is found that a better agreement between the theoretical and experimental results for the threshold of instability can be obtained by considering the energy loss. Furthermore, in this paper, it is shown experimentally that an aerostatic journal bearing with circular slot restrictors has higher stiffness and higher stability than a conventional point source bearing with inherently compensated feeding holes.

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.

Dynamic Behaviour of Tilting-Pad Journal Bearings

1995 ◽  
Vol 209 (4) ◽  
pp. 275-285 ◽  
Author(s):  
S Pagano ◽  
E Rocca ◽  
M Russo ◽  
R Russo
Keyword(s):  
Dynamic Behaviour ◽  
Static Load ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Tilting Pad ◽  
Non Linear ◽  
The Stability ◽  
Tilting Pad Journal Bearings

The dynamic behaviour of a rigid rotor on tilting-pad journal bearings system is analysed for balanced and unbalanced rotors. The study mainly regards a two-pad journal bearing symmetric with respect to the external static load. Both linear and non-linear behaviours have been analysed, with particular reference to the stability of the journal and pads equilibrium positions in the case of balanced or slightly unbalanced rotors, and to the stability of their synchronous motions in the case of considerable unbalance.

Comparison study of misalignment effect along two perpendicular directions on the stability of rigid rotor-aerostatic journal bearing system

2020 ◽  
Vol 234 (10) ◽  
pp. 1618-1634
Author(s):  
Jianbo Zhang ◽  
Han Zhao ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhushi Rao
Keyword(s):  
Journal Bearing ◽  
Thickness Distribution ◽  
Vertical Direction ◽  
Inertial Force ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Stability Threshold ◽  
Dynamic Coefficients ◽  
The Stability ◽  
Bearing System

Under misalignment condition, the film thickness distribution of aerostatic journal bearings is changed comparing with condition without misalignment, which results in the change of performances of aerostatic journal bearings. In the paper, the effects of misalignment along two perpendicular directions (along the vertical direction θ y and along the horizontal direction θ x) on the dynamic coefficients and stability thresholds of both critical whirl ratio and critical inertial force calculated by the motion equation of rigid rotor-aerostatic journal bearing system are studied comparatively. The results indicate that the dynamic coefficients, critical whirl ratio, and critical inertial force are more sensitive to θ x compared with θ y. Moreover, the stability threshold of whirl ratio reduces with increasing the misalignment degree, while stability threshold of inertial force increases with increasing the misalignment degree.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Non-linear stability analysis of micropolar fluid lubricated journal bearings with turbulent effect

2019 ◽  
Vol 71 (1) ◽  
pp. 31-39
Author(s):  
Subrata Das ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Micropolar Fluid ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Content Type ◽  
Non Linear ◽  
The Stability ◽  
Bearing System

Purpose The purpose of this paper is to investigate the effect of turbulence on the stability characteristics of finite hydrodynamic journal bearing lubricated with micropolar fluid. Design/methodology/approach The non-dimensional transient Reynolds equation has been solved to obtain the non-dimensional pressure field which in turn used to obtain the load carrying capacity of the bearing. The second-order equations of motion applicable for journal bearing system have been solved using fourth-order Runge–Kutta method to obtain the stability characteristics. Findings It has been observed that turbulence has adverse effect on stability and the whirl ratio at laminar flow condition has the lowest value. Practical implications The paper provides the stability characteristics of the finite journal bearing lubricated with micropolar fluid operating in turbulent regime which is very common in practical applications. Originality/value Non-linear stability analysis of micropolar fluid lubricated journal bearing operating in turbulent regime has not been reported in literatures so far. This paper is an effort to address the problem of non-linear stability of journal bearings under micropolar lubrication with turbulent effect. The results obtained provide useful information for designing the journal bearing system for high speed applications.

Influence of geometric parameters and operating conditions on the thermohydrodynamic behaviour of plain journal bearings

2000 ◽  
Vol 214 (5) ◽  
pp. 445-457 ◽  
Author(s):  
I Pierre ◽  
M Fillon
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Thermal Dissipation ◽  
Radial Clearance ◽  
Geometric Factors ◽  
Essential Components ◽  
Mass Flowrate

Hydrodynamic journal bearings are essential components of high-speed machinery. In severe operating conditions, the thermal dissipation is not a negligible phenomenon. Therefore, a three-dimensional thermohydrodynamic (THD) analysis has been developed that includes lubricant rupture and re-formation phenomena by conserving the mass flowrate. Then, the predictions obtained with the proposed numerical model are validated by comparison with the measurements reported in the literature. The effects of various geometric factors (length, diameter and radial clearance) and operating conditions (rotational speed, applied load and lubricant) on the journal bearing behaviour are analysed and discussed in order to inform bearing designers. Thus, it can be predicted that the bearing performance obtained highly depends on operating conditions and geometric configuration.

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