Solutions of Finite Journal Bearings With Incomplete Films

1975 ◽  
Vol 97 (1) ◽  
pp. 89-93 ◽  
Author(s):  
I. Etsion ◽  
O. Pinkus
Keyword(s):  
Boundary Conditions ◽  
Reynolds Equation ◽  
Journal Bearings ◽  
Operating Parameters ◽  
Previous Theory ◽  
Feed Pressure ◽  
Theory And Experiment

The Reynolds equation is here solved for journal bearings using new upstream boundary conditions which reflect the fact that starting films in these bearings are often incomplete. The work is an extension of previously published results for short bearings to the case of finite bearings of arbitrary width and arbitrary extent of inlet film. An expression is also derived relating the width of the inlet film with the lubricant feed pressure and the bearing operating parameters, when the lubricant is fed through a hole. The results provide an explanation for the profound lack of agreement between previous theory and experiment with regard to side leakage in journal bearings.

Behavior of Finite Journal Bearings Under Dynamic Loading Conditions

1980 ◽  
Vol 102 (3) ◽  
pp. 333-338 ◽  
Author(s):  
G. S. A. Shawki ◽  
M. O. A. Mokhtar ◽  
Z. S. Safar
Keyword(s):  
Boundary Conditions ◽  
Computer Program ◽  
Variational Methods ◽  
Axial Length ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
The Third ◽  
Dynamic Loading Conditions ◽  
Generalized Reynolds Equation

Performance characteristics for a complete journal bearing of finite axial length are obtained analytically using a new set of boundary conditions. The generalized Reynolds equation is transformed, in the present analysis, into three ordinary differential equations, two of which being readily integrable while the third is solved by variational methods. By the aid of a specially devised computer program, the validity of the analysis has been assured when applied to prescribed journal loci including stationary, circular, elliptical, and linear harmonic journal oscillation.

On the Performance of Journal Bearings Under Conditions of Film Rupture, Part II

1975 ◽  
Vol 97 (4) ◽  
pp. 591-598
Author(s):  
W. A. Crosby ◽  
E. M. Badawy
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Finite Length ◽  
Infinite Number ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Characteristics ◽  
Film Rupture ◽  
Rupture Part

An analytical analysis of journal bearing performance under conditions of film rupture by separation and by cavitation is performed. The ruptured region is considered to have an infinite number of cavities. The boundary condition of Reynolds’ equation at the trailing edge is influenced by the bearing’s operating characteristics and the method of oil admission. A variational solution is given in order to extend the applicability of the boundary conditions to bearings of finite length.

Analysis of Short Journal Bearings With New Upstream Boundary Conditions

1974 ◽  
Vol 96 (3) ◽  
pp. 489-496 ◽  
Author(s):  
I. Etsion ◽  
O. Pinkus
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Reynolds Equation ◽  
Journal Bearings ◽  
Diameter Ratio ◽  
General Analysis ◽  
New Approach ◽  
Starting Condition ◽  
Lubricating Film ◽  
Limiting Case

The Reynolds equation, for short journal bearings, is treated with a new approach to the boundary condition at the beginning of the lubricating film. The nondimensional hydrodynamic side leakage and other performance characteristics of the bearing are shown to be a function not only of Sommerfeld number and width over diameter ratio but also of another parameter which depends on the starting condition at the film inlet. The results obtained by other investigators till now are shown to be only a limiting case of the more general analysis given here. This work is the first part of a larger work embracing the analysis of finite bearings.

Influences of journal with 3D form errors on dynamic coefficients of hydrodynamic bearings yielded to JFO boundary conditions

2018 ◽  
Vol 233 (2) ◽  
pp. 289-302 ◽  
Author(s):  
Xun Ma ◽  
Wubin Xu ◽  
Xueping Zhang ◽  
Siyi Ding
Keyword(s):  
Boundary Conditions ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Form Error ◽  
Form Errors ◽  
Damping Coefficients ◽  
Dynamic Coefficients ◽  
Stiffness And Damping

The dynamic characteristics of the journal with form error are analyzed, including normalized stiffness and damping coefficients. A new expression for journal surface with form error is presented, which is capable of formulating any types of form errors on the journal, and the dimensionless Reynolds equation is renewed and solved suffering from the Jakobsson, Floberg, and Olsson boundary conditions. The results show that form errors do have a significant influence on the dynamic performance of journal bearings and that the uncertainty attribute of form error could result in variations of dynamic properties so significantly that the system might operate in an entirely different way. Therefore, it is necessary to take more operating information into account, such as the elaborate state of the journal surface, in order to predict the bearing performance more accurately.

Performance Characteristics of Flared Bearings

1980 ◽  
Vol 102 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Oscar Pinkus ◽  
Sargit S. Bupara
Keyword(s):  
Finite Difference ◽  
Boundary Conditions ◽  
Reynolds Equation ◽  
Finite Difference Methods ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Wide Range ◽  
Manufacturing Errors ◽  
Difference Methods ◽  
Journal Misalignment

The paper offers an analysis of finite journal bearings having an axially variable clearance. Such bearings are encountered either as a consequence of manufacturing errors and wear, or as configurations specifically designed to accommodate journal misalignment. The Reynolds equation is solved for the appropriate boundary conditions and film geometry by finite difference methods. Tables of computer solutions and a number of graphs provide the performance characteristics of misaligned bearings for a wide range of parameters. The results show that striking advantages can be achieved by the use of flared bearings for cases of moderate and severe journal misalignment.

scholarly journals Effects of velocity-slip and viscosity variation on journal bearings

2004 ◽  
Vol 46 (1) ◽  
pp. 143-155 ◽  
Author(s):  
R. Raghavendra Rao ◽  
K. R. Prasad
Keyword(s):  
Boundary Conditions ◽  
Coefficient Of Friction ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Viscous Layer ◽  
The Coefficient Of Friction ◽  
Viscosity Variation

AbstractA generalised form of the Reynolds equation for two symmetrical surfaces is derived by considering slip at the bearing surfaces. This equation is then used to study the effects of velocity-slip for the lubrication of journal bearings using half-Sommerfeld boundary conditions. Expressions for pressure and load capacity and the coefficient of friction are obtained and numerically analysed for various parameters. It is found that the load capacity decreases with slip. This is unfavourable for lubrication. The coefficient of friction decreases with a high viscous layer and increases with slip.

Bifurcation Analysis of Self-Acting Gas Journal Bearings

2001 ◽  
Vol 123 (4) ◽  
pp. 755-767 ◽  
Author(s):  
Cheng-Chi Wang ◽  
Cha’o-Ku`ang Chen
Keyword(s):  
Dynamic Behavior ◽  
Reynolds Equation ◽  
Rotational Velocity ◽  
Power Spectra ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Finite Differences Method ◽  
Subharmonic Response ◽  
Rotor Center ◽  
Rotor Mass

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

The Effect of Journal Bearing Misalignment on Load and Cavitation for Non-Newtonian Lubricants

1986 ◽  
Vol 108 (4) ◽  
pp. 645-654 ◽  
Author(s):  
R. H. Buckholz ◽  
J. F. Lin
Keyword(s):  
Reynolds Equation ◽  
Numerical Solutions ◽  
Journal Bearings ◽  
Surface Boundary ◽  
Film Rupture ◽  
Aspect Ratios ◽  
Free Surface Boundary Condition ◽  
Load Carrying ◽  
Boundary Location ◽  
Surface Boundary Condition

An analysis for hydrodynamic, non-Newtonian lubrication of misaligned journal bearings is given. The hydrodynamic load-carrying capacity for partial arc journal bearings lubricated by power-law, non-Newtonian fluids is calculated for small valves of the bearing aspect ratios. These results are compared with: numerical solutions to the non-Newtonian modified Reynolds equation, with Ocvirk’s experimental results for misaligned bearings, and with other numerical simulations. The cavitation (i.e., film rupture) boundary location is calculated using the Reynolds’ free-surface, boundary condition.

NEW MODELS IN MICROPOLAR FLUID AND THEIR APPLICATION TO LUBRICATION

2005 ◽  
Vol 15 (03) ◽  
pp. 343-374 ◽  
Author(s):  
GUY BAYADA ◽  
NADIA BENHABOUCHA ◽  
MICHÈLE CHAMBAT
Keyword(s):  
Boundary Condition ◽  
Friction Coefficient ◽  
Boundary Conditions ◽  
Existence And Uniqueness ◽  
Micropolar Fluid ◽  
Reynolds Equation ◽  
Slip Boundary Condition ◽  
Slip Boundary ◽  
New Models ◽  
Uniqueness Of The Solution

A thin micropolar fluid with new boundary conditions at the fluid-solid interface, linking the velocity and the microrotation by introducing a so-called "boundary viscosity" is presented. The existence and uniqueness of the solution is proved and, by way of asymptotic analysis, a generalized micropolar Reynolds equation is derived. Numerical results show the influence of the new boundary conditions for the load and the friction coefficient. Comparisons are made with other works retaining a no slip boundary condition.

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