Steady-State and Dynamic Behaviour of Multi-Recess Hybrid Oil Journal Bearings

1979 ◽  
Vol 21 (5) ◽  
pp. 345-351 ◽  
Author(s):  
M. K. Ghosh ◽  
B. C. Majumdar ◽  
J. S. Rao
Keyword(s):  
Perturbation Theory ◽  
Steady State ◽  
Theoretical Analysis ◽  
Dynamic Behaviour ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Time Dependent ◽  
Damping Coefficients ◽  
Stiffness And Damping

A theoretical analysis of the steady-state and dynamic characteristics of multi-recess hybrid oil journal bearings is presented. A perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term. Load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.

Dynamic Characteristic of Multirecess Externally Pressurized Oil Journal Bearing

1978 ◽  
Vol 100 (4) ◽  
pp. 467-471 ◽  
Author(s):  
M. K. Ghosh
Keyword(s):  
Perturbation Theory ◽  
Theoretical Analysis ◽  
Dynamic Characteristic ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Harmonic Vibrations ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Generalized Reynolds Equation

This paper describes a theoretical analysis of the dynamic behavior of multirecess externally pressurized oil journal bearings for a nonrotating journal subjected to plane harmonic vibrations. The generalized Reynolds’ equation for a finite bearing has been solved using perturbation theory. Stiffness and damping characteristics of a capillary compensated bearing are given.

Helical-Grooved Journal Bearing Operated in Turbulent Regime

1970 ◽  
Vol 92 (2) ◽  
pp. 346-357 ◽  
Author(s):  
C. Y. Chow ◽  
J. H. Vohr
Keyword(s):  
Steady State ◽  
Journal Bearing ◽  
Critical Mass ◽  
Reynolds Numbers ◽  
Turbulent Regime ◽  
Damping Coefficients ◽  
Radial Stiffness ◽  
Performance Curves ◽  
Stiffness And Damping ◽  
Laminar And Turbulent Regimes

An analysis for helical bearings operated in turbulent regime, with negligible inertia in an incompressible fluid film, was performed [10, 11]. The analysis is based on the linearised lubrication theory developed by Ng and Pan [4]. The outlines for this analysis and, in particular, the bearing performance data for various helical groovings are given in this paper. The data presented include the bearing performance at the steady state, the stiffness and damping coefficients, and the critical mass of journal in both laminar and turbulent regimes. To facilitate designs, these data are computed for optimal geometries of helical grooved bearings to provide maximum radial stiffness at various Reynolds numbers. In addition, the effect of external pressurized supply of lubricant are shown in the performance curves.

Steady-State and Dynamic Analyses of Gas-Lubricated Hybrid Journal Bearings

1969 ◽  
Vol 91 (1) ◽  
pp. 171-180 ◽  
Author(s):  
W. Shapiro
Keyword(s):  
Steady State ◽  
Journal Bearing ◽  
Load Capacity ◽  
External Pressure ◽  
Journal Bearings ◽  
Preliminary Design ◽  
Wide Range ◽  
Dynamic Analyses ◽  
Flow Charts ◽  
Hybrid Bearing

The inherent limitations of load capacity and stability of hydrodynamic gas-lubricated bearings can be reduced by introducing external pressure and creating a hybrid bearing. Numerical computerized analyses of a hybrid journal bearing are discussed; separate developments are presented for steady-state and dynamic characteristics. The steady-state analysis provides performance over a wide range of operating parameters; the more complicated and lengthy dynamic analysis determines stability of the bearing-rotor system using geometry based upon steady-state results. Simplified flow charts of the computer programs are included. The analyses are applied to the preliminary design of a hybrid journal bearing.

Dynamic Stiffness and Damping Coefficients of Aerostatic, Porous, Journal Bearings

1978 ◽  
Vol 20 (5) ◽  
pp. 291-296 ◽  
Author(s):  
N. S. Rao ◽  
B. C. Majumdar
Keyword(s):  
Continuity Equation ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Dynamic Pressure ◽  
Dynamic Stiffness ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Damping Coefficients ◽  
Design Charts ◽  
Stiffness And Damping

A periodic (displacement) disturbance is imposed on an aerostatic, porous, journal bearing of finite length under steady-state conditions. The dynamic pressure distribution is obtained by a pressure perturbation analysis of Reynolds equation and a modified flow continuity equation in a porous medium. Dynamic stiffness and damping coefficients for different operating conditions are calculated numerically, using a digital computer, and presented in the form of design charts.

scholarly journals Stability of a Rigid Rotor Supported on Flexible Oil Journal Bearings

1988 ◽  
Vol 110 (1) ◽  
pp. 181-187 ◽  
Author(s):  
B. C. Majumdar ◽  
D. E. Brewe ◽  
M. M. Khonsari
Keyword(s):  
Steady State ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Elasticity Parameter ◽  
Damping Coefficients ◽  
Pressure Dependent Viscosity ◽  
The Stability ◽  
Dependent Viscosity ◽  
Stiffness And Damping

This investigation deals with the stability characteristics of oil journal bearings, including the effect of elastic distortions in the bearing liner. Graphical results are presented for (1) steady-state load, (2) stiffness and damping coefficients, and (3) the stability. These results are given for various slenderness ratios, eccentricity ratios, and elasticity parameters. The lubricant is first assumed to be isoviscous. The analysis is then extended to the case of a pressure-dependent viscosity. It has been found that stability decreases with increase of the elasticity parameter of the bearing liner for heavily loaded bearings.

Feasibility study of a turbocharger rotor supported by air foil bearings with diameter of 17 mm focusing on rotordynamic performance

2018 ◽  
Vol 233 (5) ◽  
pp. 1331-1344
Author(s):  
Jiajia Yan ◽  
Zhansheng Liu ◽  
Guanghui Zhang ◽  
Xiangyu Yu ◽  
Liang Xu
Keyword(s):  
Feasibility Study ◽  
Journal Bearing ◽  
Negative Influence ◽  
Journal Bearings ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Damping Coefficients ◽  
Stable Operating ◽  
Lift Off ◽  
Stiffness And Damping

This paper presents the feasibility study of an oil-free turbocharger with journal bearing diameter of 17 mm. Rotordynamic performance of a turbocharger rotor, supported by two identical bump-type foil journal bearings and a pair of foil thrust bearings, is predicted and tested. High-pressure cold nitrogen is adopted to drive the turbocharger rotor. In rotordynamic analysis, the critical speeds and logarithmic decrement of the turbocharger rotor are predicted by employing the finite element method, in which the stiffness and damping coefficients of foil journal bearings and aerodynamic cross-coupled stiffness of the turbine are taken into account. Compared with experimental results, the accuracy of the prediction for rotordynamic analysis is verified for 7.82% marginal error of the critical speed. During the experiment, three foil journal bearings with different nominal clearances are manufactured and tested. The maximum stable operating speed reaches 105,000 r/min for this 17-mm-diameter oil-free turbocharger rotor system. Test results indicate the nominal clearance has a negative influence on threshold speed of sub-synchronous motions. When the nominal clearance is relatively small, the foil journal bearing could not lift off due to a large starting torque, while sub-synchronous motions would emerge under a large nominal clearance because of the reduced stiffness and damping coefficients of foil journal bearings.

Static and dynamic characteristics and stability analysis of high-speed water-lubricated hydrodynamic journal bearings

2021 ◽  
pp. 135065012110270
Author(s):  
Bo Xu ◽  
Hun Guo ◽  
Xiaofeng Wu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Load Capacity ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Inertia Effect ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Stiffness And Damping

The purpose of this paper is to analyze the influence of turbulent, inertia, and misaligned effects on the static and dynamic characteristics and stability of high-speed water-lubricated hydrodynamic journal bearings. Based on the Navier–Stokes equation, the mixing-length theory, and the essential assumption that the velocity profile is not strongly affected by inertia force, the fluid lubrication model with turbulent, inertia, and misaligned effects is established, and then the stability analysis of bearings is carried out based on the equation of motion with four degrees of freedom. The model is solved by the finite difference method and the numerical results are compared under different operating conditions. The results show that the turbulent effect greatly increases the load capacity, power consumption, stiffness and damping coefficients, and stability of bearings, and the inertia effect significantly increases the volume flow rate of bearings, and the misaligned effect increases the load capacity, stiffness and damping coefficients, and stability of bearings. In high rotary speed and moderate eccentricity ratios, the influence of the inertia effect on the load capacity, stiffness coefficients, and stability cannot be neglected.

The Effect of Thermal Distortion on the Characteristics of Large Hydrodynamic Bearings

1988 ◽  
Vol 202 (3) ◽  
pp. 219-225 ◽  
Author(s):  
P G Morton ◽  
J H Johnson ◽  
G D Wale
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Journal Bearing ◽  
Thermal Distortion ◽  
Hydrodynamic Bearings ◽  
Damping Coefficients ◽  
Dynamic Coefficients ◽  
Oil Whirl ◽  
Stabilizing Effect ◽  
Stiffness And Damping

An experimental investigation has been carried out on a 350 mm partial arc journal bearing to determine the steady state characteristics and the stiffness and damping coefficients. The bearing was found to distort due to thermal influences and the pressure distribution and dynamic coefficients consequently differed markedly from those obtained using standard theoretical techniques. Calculations of the speed at which resonant oil whirl develops in a rotor supported by bearings of this type show that the threshold speed is far higher using experimental coefficients than theoretical coefficients. It is concluded that thermal distortion has a significant stabilizing effect on large hydrodynamic bearings.

On the Dynamics of Elastohydrodynamic Mixed Lubricated Ball Bearings. Part I: Formulation of Stiffness and Damping Coefficients

2005 ◽  
Vol 219 (6) ◽  
pp. 411-421 ◽  
Author(s):  
M Sarangi ◽  
B. C. Majumdar ◽  
A. S. Sekhar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Design Parameters ◽  
Asperity Contact ◽  
Damping Coefficients ◽  
Damping Characteristics ◽  
Stiffness And Damping

The problems of stiffness and damping characteristics of isothermal elastohydrodynamic mixed lubricated point contact are evaluated numerically considering surface roughness effect including asperity contact load. A set of equations under steady-state and dynamic conditions is derived from the classical Reynolds equation, using linear perturbation method. The elasticity equation and steady-state Reynolds equation are solved simultaneously for finding the steady-state pressure distribution, using finite difference method. Then, the set of perturbed equations is solved for the dynamic pressure distribution in the contact. A Gaussian surface roughness is adopted to model both surface roughness and mixed lubrication. Total load capacity of the contact is calculated from the lubricant film pressure and contact pressure distribution. Results are compared with those of smooth isothermal cases. The stiffness and damping coefficients of the contact are determined using the dynamic pressures. The asperity contact stiffness is calculated separately. Effect of various design parameters on stiffness and damping characteristics of a ball bearing is investigated.

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