Re-Examination of Film Rupture Boundary Condition in Hydrodynamic Lubrication Under Inertia Effect

1991 ◽  
Vol 113 (3) ◽  
pp. 604-608 ◽  
Author(s):  
A. Mori ◽  
H. Mori
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Pressure Distribution ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Careful Consideration ◽  
Inertia Effect ◽  
Film Rupture ◽  
The Difference ◽  
Inertia Forces

This paper presents discussions on the choice and handling of film rupture boundary conditions for the hydrodynamic lubrication under the effect of lubricant inertia forces. Many researchers have analyzed this inertia effect in converging-diverging hydrodynamic wedge and squeeze films without careful consideration of the problem caused by the film rupture boundary conditions used. To reveal the importance of the problem, the marked difference in pressure distribution produced by the difference in boundary conditions is presented for an infinitely long, steadily loaded, cylindrical journal bearing.

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.

A Note on Film Rupture in Hydrodynamic Lubrication

1987 ◽  
Vol 109 (3) ◽  
pp. 562-566 ◽  
Author(s):  
Terukazu Ota
Keyword(s):  
Experimental Data ◽  
Boundary Condition ◽  
Experimental Study ◽  
Boundary Conditions ◽  
Present Model ◽  
Hydrodynamic Lubrication ◽  
Correction Term ◽  
Plane Geometry ◽  
Separation Boundary ◽  
Film Rupture

A theoretical and experimental study has been made for a film repture in hydrodynamic lubrication. A model is proposed on boundary conditions at the film rupture point. It contains a pressure correction term as a parameter, which simplifies that derived by Coyne and Elrod, and the so-called separation boundary condition. Some experiments have been conducted for a flow in a cylinder-plane geometry. It is found that numerical results using the present model agree reasonably well with the present and previous experimental data.

Inertia Effect in Hydrodynamic Lubrication With Film Rupture

1987 ◽  
Vol 109 (1) ◽  
pp. 86-90 ◽  
Author(s):  
H. I. You ◽  
S. S. Lu
Keyword(s):  
Reynolds Number ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Film Rupture ◽  
Minimum Film Thickness ◽  
Rupture Model ◽  
Modified Reynolds Equation

The modified Reynolds equation in conjunction with the modified Coyne-Elrod rupture model is used to investigate the inertia effect on the pressure distribution in converging-diverging bearings. The modified Reynolds equation is solved analytically for infinitely long bearings, including the cylinder-plane bearing and the journal bearing. The results showed that the fluid inertia tends to stretch the fluid film and to move the film rupture point farther downstream. The effects are profound even at a moderate value of the reduced Reynolds number, Re* ≈ 0.13 based on the minimum film thickness.

Boundary Conditions and Initial Value Lines for Unsteady Homentropic Flow Calculations

1970 ◽  
Vol 21 (2) ◽  
pp. 145-162 ◽  
Author(s):  
W. A. Woods ◽  
H. Daneshyar
Keyword(s):  
Boundary Condition ◽  
Analytical Solution ◽  
Boundary Conditions ◽  
Good Accuracy ◽  
Numerical Calculations ◽  
Time Dependent ◽  
Straight Pipe ◽  
Initial Value ◽  
Use Of Time ◽  
The Difference

SummaryA detailed discussion on the difference between an initial value line and a line characterised by a boundary condition has been presented. Two types of boundaries are described and illustrated. To examine each boundary, several different calculations have been performed for a straight pipe. The results of the numerical calculations are compared with an analytical solution. It is shown that known pressure and velocity at the pipe ends give the most accurate results. Comparisons are also made between several practical types of calculations which give similar findings. The use of time-dependent boundaries can lead to errors as large as 40 per cent in derived results. It is shown that good accuracy can be restored by converting the boundaries into initial value lines. It is concluded that in general no more than one time-dependent boundary should be used in any calculation. Finally it is demonstrated that errors are not revealed by means of pressure diagrams alone.

Experimental Investigation into the Effect of the Thermal Boundary Condition on Heat Transfer in the Entrance Region of a Pipe

1964 ◽  
Vol 6 (3) ◽  
pp. 250-255 ◽  
Author(s):  
W. B. Hall ◽  
S. A. Khan
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Reynolds Numbers ◽  
Entrance Region ◽  
Uniform Heat Flux ◽  
Layer Formation ◽  
Uniform Temperature ◽  
Significant Difference ◽  
The Difference ◽  
Boundary Layer Formation

Experimental results are presented for forced convection in the entrance region of a pipe; the results were obtained using both the boundary condition of uniform heat flux and that of uniform temperature. A significant difference which is attributable to the different boundary conditions was observed for Reynolds numbers below about 3 times 104, but at higher Reynolds numbers the difference rapidly diminishes. An approximate numerical solution for the early stages of boundary layer formation on the pipe walls gave similar differences between the two boundary conditions as were observed in the experiment.

Separation Cavitation in Lightly Loaded Fluid Film Bearings with Both Surfaces in Motion

1974 ◽  
Vol 16 (3) ◽  
pp. 147-155 ◽  
Author(s):  
C. M. Taylor
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Experimental Work ◽  
Journal Bearing ◽  
Fluid Film ◽  
Operating Parameters ◽  
Separation Boundary ◽  
Fluid Film Bearings ◽  
Theoretical Predictions ◽  
Bounding Surfaces

For lightly loaded fluid film bearings in which gaseous cavitation occurs, application of the continuity boundary condition at the liquid-gas interface is not satisfactory. Two alternative boundary conditions have been postulated. The purpose of this paper is to examine the separation boundary condition; in particular, the effect of both bounding surfaces being in motion is studied. This situation might be used as a basis for experimental work designed to select the most appropriate boundary condition for lightly loaded bearings. In Part 2, the boundary condition is used to analyse the cylinder-plane and journal bearing configurations. The theoretical predictions for the operating parameters are examined to see if their magnitudes and/or trends could be used for comparing the available cavitation boundary conditions.

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.

Paper 14: Hydrodynamic Lubrication of Lightly Loaded Finite Cylinders

1966 ◽  
Vol 181 (15) ◽  
pp. 112-116
Author(s):  
R. J. Boness
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Velocity Gradient ◽  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Fluid Properties ◽  
Theoretical Results ◽  
Finite Cylinders

Theoretical results of the load-carrying capacity of lightly loaded finite cylinders indicate that the effect of side leakage can be secondary to upstream boundary condition considerations. Neglecting side leakage the calculations are extended to cover the experimental results of Crook into the régime where the fluid properties are pressure dependent. The results support the adoption of the new velocity and velocity gradient boundary conditions suggested by Lauder.

The Effect of Elastic Distortions on Journal Bearing Performance

1967 ◽  
Vol 89 (4) ◽  
pp. 409-415 ◽  
Author(s):  
J. O’Donoghue ◽  
D. K. Brighton ◽  
C. J. K. Hooke
Keyword(s):  
Exact Solution ◽  
Pressure Distribution ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Wide Range ◽  
Constant Viscosity ◽  
Outside Diameter

This paper presents a solution to the problem of hydrodynamic lubrication of journal bearings taking into account the elastic distortions of the shaft and the bearing. The exact solution for determining the elastic deformation for a given pressure distribution around a bearing is given, together with the reiterative procedure adopted to find the pressure distribution which satisfies both the hydrodynamic and elastic requirements of the system. Results are given which have been derived for a material with a Poisson’s ratio of 0.28, but other values such as 0.33 do not incur substantial errors. The results can be applied to a wide range of operating conditions using the nondimensional group of terms suggested in the paper. The bearing is assumed to be infinite in length, and infinite in thickness. The latter assumption is shown to be valid for a particular case where the outside diameter of the bearing shell is 3.5 times the shaft diameter. A further assumption in the calculation is a condition of constant viscosity of the lubricant existing around the bearing.

Mathematical Model for Gas Bearing With Holes of Tangential Supply

1999 ◽  
Vol 121 (2) ◽  
pp. 301-305 ◽  
Author(s):  
L Q. Liu ◽  
C. Z. Chen
Keyword(s):  
Mathematical Model ◽  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Inertia Effect ◽  
Governing Equations ◽  
Gas Bearing ◽  
Typical Design

To investigate the dynamic characteristics of gas bearings with holes of tangential supply (TS bearing), drawing on the modified Reynolds equations proposed by Mori, we present new governing equations and their reasonable boundary conditions. Using this mathematical model, the inertia effect of the supplied gas on the aerodynamic film force can be evaluated properly. The governing equations are solved numerically using Finite Element Method (FEM), and the pressure distribution of the gas in the bearing, the critical whirl ratio and so on, are calculated for a typical design. Some results for a cylindrical journal bearing (CJ bearing) and ordinary bearing with holes of radial supply (RS bearing) are also provided for comparison.

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