Inertia Effects on Film Rupture in Hydrodynamic Lubrication

1995 ◽  
Vol 117 (4) ◽  
pp. 685-690
Author(s):  
Terukazu Ota ◽  
Hiroyuki Yoshikawa ◽  
Makoto Hamasuna ◽  
Takeshi Motohashi ◽  
Soshu Oi
Keyword(s):  
Experimental Data ◽  
Boundary Condition ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Numerical Data ◽  
Wave Number ◽  
Film Rupture ◽  
Rupture Surface ◽  
Inertia Effects ◽  
Good Agreement

A perturbation analysis was made to study the effect of inertia on the film rupture in hydrodynamic lubrication using a modified Reynolds equation. A simplified boundary condition at film rupture proposed by Ota (1987) was employed. The theory was extended to investigate the wave number of the film rupture surface and to investigate the effect of gas bubbles included in the lubricant. Numerical calculations were carried out for a cylinder-plane bearing and are compared with previous experimental and numerical data. The effects of inertia on film rupture characteristics are clarified and the present numerical results are found to be in good agreement with earlier experimental data.

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.

A Theoretical Model of Striated Film-Rupture Applied to the Cylinder-Plane

1985 ◽  
Vol 107 (3) ◽  
pp. 419-422 ◽  
Author(s):  
C. Fall
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Perturbation Analysis ◽  
Reynolds Equation ◽  
Plane Geometry ◽  
Time Dependent ◽  
Linear Perturbation ◽  
Film Rupture ◽  
Successful Prediction

The author has previously presented a theoretical model of striated film-rupture consisting of a time-dependent linear perturbation analysis applied to the Reynolds equation. After review this model is applied to the cylinder-plane geometry for comparison with theoretical and experimental data due to Savage. Successful prediction of the number of striations for varying (ηU/T) and (R/h0) is achieved.

On the Comparison Between Lubrication Theory, Including Turbulence and Inertia Forces, and Some Existing Experimental Data

1975 ◽  
Vol 97 (3) ◽  
pp. 439-448 ◽  
Author(s):  
V. N. Constantinescu ◽  
S. Galetuse ◽  
F. Kennedy
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Reynolds Numbers ◽  
Lubrication Theory ◽  
Incoming Flow ◽  
Flow Conditions ◽  
Film Rupture ◽  
Inertia Forces ◽  
Proper Consideration ◽  
Good Agreement

The results obtained by using lubrication theory, including inertia forces, are checked against experimental data concerning flows in relatively thin films at moderate and large Reynolds numbers. It is shown that a reasonably good agreement is obtained provided that the peculiar features of the experimental flow are properly taken into account; namely, proper consideration of the type of flow (laminar, transition, turbulent), proper evaluation of the region where lubrication flow prevails, entrance flow conditions (relating the flow into the film to the incoming flow), conditions for film rupture, cavitation or separation.

The half-wetted bearing. Part 1: Extended Reynolds equation

2003 ◽  
Vol 217 (1) ◽  
pp. 1-14 ◽  
Author(s):  
H. A. Spikes
Keyword(s):  
Boundary Condition ◽  
Solid Surface ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Critical Shear Stress ◽  
Slip Boundary Condition ◽  
Low Friction ◽  
Slip Boundary ◽  
Lubrication Condition ◽  
Bearing Part

Recent research has shown that, when a liquid is partially wetting or non-wetting against a very smooth solid surface, the conventional no-slip boundary condition can break down. Under such circumstances, the Reynolds equation is no longer applicable. In the current paper, the Reynolds equation is extended to consider the sliding, hydrodynamic lubrication condition where the lubricant has a no-slip boundary condition against the moving solid surface but can slip at a critical shear stress against the stationary surface. It is shown that such a ‘half-wetted’ bearing is able to combine good load support resulting from fluid entrainment with very low friction due to very low or zero Couette friction.

Analysis of Thermal Effects in Hydrodynamic Bearings

1986 ◽  
Vol 108 (2) ◽  
pp. 219-224 ◽  
Author(s):  
R. Boncompain ◽  
M. Fillon ◽  
J. Frene
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Effects ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Heat Transfer Equation ◽  
Reversed Flow ◽  
Theoretical Results ◽  
Generalized Reynolds Equation ◽  
Good Agreement

A general THD theory and a comparison between theoretical and experimental results are presented. The generalized Reynolds equation, the energy equation in the film, and the heat transfer equation in the bush and the shaft are solved simultaneously. The cavitation in the film, the lubricant recirculation, and the reversed flow at the inlet are taken into account. In addition, the thermoelastic deformations are also calculated in order to define the film thickness. Good agreement is found between experimental data and theoretical results which include thermoelastic displacements of both the shaft and the bush.

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.

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.

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.

Numerical Analysis of Static Characteristics at Start of Operation in Porous Journal Bearings With Sealed Ends

1999 ◽  
Vol 121 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Satoru Kaneko ◽  
Hiroyuki Takabatake ◽  
Kanya Ito
Keyword(s):  
Hydrodynamic Lubrication ◽  
Numerical Data ◽  
Porous Matrix ◽  
Mixed Lubrication ◽  
Graphical Form ◽  
Static Characteristics ◽  
Film Rupture ◽  
Running Time ◽  
Oil Film ◽  
Lubrication Conditions

Static characteristics at the start of the operation are theoretically investigated in a porous journal bearing with sealed ends lubricated only by the oil initially provided within its pores. This is a preliminary study for estimating the variation of these characteristics with running time. A simple analytical model of the mixed lubrication regime is proposed on the basis of the assumption that the external forces acting on the journal, i.e., the applied static load, the oil-film force and the force at the boundary friction part, are balanced. Numerical results show that air penetrates into the porous matrix at the oil-film rupture zone due to negative pressure in the porous matrix; this causes the reduction of oil content within the porous matrix and contributes to formation of the oil film in the bearing clearance. The oil leakage from the porous matrix induced by the air penetration suggests that, even if hydrodynamic lubrication conditions are possible at the start of operation, the lubrication mode will become mixed or boundary lubrication conditions with running time. The numerical data on the static characteristics are presented in graphical form, illustrating the effects of the Sommerfeld number in the hydrodynamic and mixed lubrication regimes.

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.

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