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

1975 ◽  
Vol 97 (4) ◽  
pp. 585-590 ◽  
Author(s):  
W. A. Crosby ◽  
E. M. Badawy
Keyword(s):  
Boundary Condition ◽  
Journal Bearings ◽  
Film Rupture ◽  
Separation Line ◽  
Cavity Profile ◽  
Rupture Part ◽  
Different Depths

A model of film rupture taking into account both the finger-pattern and the flow carried away over and/or under the cavity is considered. A tractable boundary condition is derived by assuming that the Reynolds flow is retained in the vicinity of the cavity. The pressure isobars and cavity profile are shown at different depths of the clearance space. Thus, the shape of the separation line is obtained. A modification is suggested so that the boundary condition may accommodate the occurrence of cavitation at higher loads.

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.

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.

Performance Characteristics of Finite Width Journal Bearings Under the Separation Boundary Condition

1986 ◽  
Vol 108 (2) ◽  
pp. 178-183 ◽  
Author(s):  
M. Nakai ◽  
T. Kazamaki ◽  
T. Hatake
Keyword(s):  
Boundary Condition ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Experimental Results ◽  
Finite Width ◽  
Separation Boundary ◽  
Physical Consideration ◽  
Calculation Results

The separation boundary condition is considered to be comparatively exact in the physical consideration of the supposition. The calculated performance characteristics applied to infinite width journal bearings are related to experimental results to some extent. However, performance characteristics applied to finite width journal bearings, which might be able to explain the experimental results more precisely, have been unknown. The present paper describes the application of the separation boundary condition to finite width journal bearings, and calculation results of some performance characteristics. The results are related to well-known experimental results in several respects.

Implementation of a Cavitation Algorithm into a Procedure for the Prediction of Non-Newtonian Flow in Hydrodynamic Journal Bearings

1987 ◽  
Vol 201 (6) ◽  
pp. 449-456
Author(s):  
P D Williams ◽  
G R Symmons
Keyword(s):  
Effective Viscosity ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Navier Stokes ◽  
Newtonian Flow ◽  
Film Rupture ◽  
Navier Stokes Equations ◽  
Finite Breadth ◽  
Newtonian Liquids

A procedure for solving the Navier–Stokes equations for the steady, three-dimensional, cavitated flow of non-Newtonian liquids within finite-breadth journal bearings is described. The method uses a finite difference approach, together with a technique known as SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) which has now become well established in the field of computational fluid dynamics. The concept of ‘effective viscosity’ to describe the non-linear dependence of shear stress on shear rate is used to predict the performance of bearings having a single axial inlet groove situated at the position of maximum clearance between the shaft and housing. The implementation of a cavitation algorithm into the equation set allows the loci of film rupture and reformation in the vicinity of the supply groove and elsewhere to be traced, these having a particularly important influence on the predicted lubricant flowrate. Results are obtained for a range of non-linearity factors and lead to the conclusion that all the important indicators of bearing performance can be determined using the technique described.

scholarly journals Numerical Analysis of a Hydrodynamic Herringbone Grooved Journal Bearing

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
D. Souchet ◽  
A. Senouci ◽  
H. Zaidi ◽  
M. Amirat
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Study ◽  
Hydrodynamic Lubrication ◽  
Dynamical Behavior ◽  
Axial Flow ◽  
Journal Bearings ◽  
Film Rupture ◽  
High Rotational Speed ◽  
Fluid Leakage

In hydrodynamic lubrication, at very high rotational speed, the phenomenon of axial fluid leakage is often present. This can involve an increase of shear stress in the contact and consequently a considerable increase of the temperature. For that and in order to solve this problem, we took interest in the herringbone grooved journal bearings. The researches made before on these types of groove bearing have shown that they present a good dynamical behavior with a low eccentricity and a low axial flow. In this paper, a numerical study of a herringbone journal bearing operating behavior, under laminar and isothermal regime, is presented. The theoretical model, based on the classical Reynolds equation, is used. In order to include the film rupture and reformation, the Reynolds equation is modified using a mass conservative algorithm. To understand the behavior of these herringbone grooved journal bearings well, numerical modeling, using finite element method, has been developed. Various geometrical shapes of the herringbone grooved journal bearings have been analyzed, allowing us to limit the fluid leakage problem, by working particularly on the contact form.

Grid Transformation and Adaption Techniques Applied in the Analysis of Cavitated Journal Bearings

1990 ◽  
Vol 112 (1) ◽  
pp. 52-59 ◽  
Author(s):  
D. Vijayaraghavan ◽  
T. G. Keith
Keyword(s):  
Coordinate System ◽  
Journal Bearing ◽  
Numerical Procedure ◽  
Computer Time ◽  
Journal Bearings ◽  
Second Order ◽  
Film Rupture ◽  
Transformation Procedure ◽  
Grid Adaption ◽  
Induced Flow

An existing cavitation algorithm (a numerical procedure that automatically predicts film rupture and reformation in bearings) is modified in this paper. Second order upwinding is used to difference the shear induced flow terms in the cavitated region. A grid transformation procedure using a body fitted coordinate system and grid adaption techniques are applied to the algorithm. Four statically loaded finite journal bearing cases are analyzed. The results are compared with the results obtained using a conventional grid. The advantage of these methods is demonstrated by obtaining equal or better accuracy with a coarser grid and by the consumption of smaller amounts of computer time.

Cavitation Boundary Shapes for Submerged Short Journal Bearings Using Newtonian Lubricants

1985 ◽  
Vol 52 (4) ◽  
pp. 771-776 ◽  
Author(s):  
R. H. Buckholz
Keyword(s):  
Boundary Condition ◽  
Slenderness Ratio ◽  
Leading Edge ◽  
Journal Bearings ◽  
Surface Boundary ◽  
Lubrication Equation ◽  
Free Surface Boundary Condition ◽  
Cavitation Region ◽  
Cavitation Pressure ◽  
Surface Boundary Condition

Cavitation boundary shapes for submerged short journal bearings are investigated in this study. In this analysis, the Reynolds lubrication equation is approximated by using the bearing slenderness ratio as a small parameter. The slenderness ratio appears explicitly in the Reynolds lubrication equation. The lubrication equation is solved subjected to the boundary condition of a subambient value for the cavitation pressure and the additional Reynolds’ free-surface boundary condition along the unknown cavitation boundary. The Ocvirk short bearing solution is shown to fail near the leading edge of the cavitation region, and a matched asymptotic theory is used to determine the shape and location of this cavitated region. Cavitation bubble location and size are shown to depend on bearing aspect ratio, journal eccentricity, and cavitation pressure. Finally the present journal bearing analysis is limited to those cases where the cavitation region has a large axial extent.

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