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.

The Effect of Lubricant Inertia in Journal-Bearing Lubrication

1957 ◽  
Vol 24 (4) ◽  
pp. 494-496
Author(s):  
J. F. Osterle ◽  
Y. T. Chou ◽  
E. A. Saibel
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Hydrodynamic Theory ◽  
Simple Relationship ◽  
Inertia Effect ◽  
Laminar Regime ◽  
Steady State Operation

Abstract The Reynolds equation of hydrodynamic theory, modified to take lubricant inertia into approximate account, is applied to the steady-state operation of journal bearings to determine the effect of lubricant inertia on the pressure developed in the lubricant. A simple relationship results, relating this “inertial” pressure to the Reynolds number of the flow. It is found that the inertia effect can be significant in the laminar regime.

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.

Temporal and Convective Inertia Effects in Plain Journal Bearings With Eccentricity, Velocity and Acceleration

2011 ◽  
Author(s):  
Saeid Dousti ◽  
Jianming Cao ◽  
Amir Younan ◽  
Paul Allaire ◽  
Tim Dimond
Keyword(s):  
Reynolds Number ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Fluid Film ◽  
Navier Stokes ◽  
Inertia Effect ◽  
Inertia Effects ◽  
Low Viscosity ◽  
Fluid Film Bearings

Fluid film bearings are commonly analyzed with the conventional Reynolds equation, without any temporal inertia effects, developed for oil or other high viscosity lubricants. In applications with rapidly time varying external loads, e.g. ships on wavy oceans, temporal inertia effect should be taken into account. As rotating speeds increase in industrial machines and the reduced Reynolds number increases above the turbulent threshold, a form of linearized turbulence model is often used to increase the effective viscosity to take the turbulence into account. Other than the turbulence effect, with high reduced Reynolds number, convective inertia effect gains importance. Water or other low viscosity fluid film bearings used in subsea machines and compressors are potential applications with a highly reduced Reynolds number.” This paper extends the theory originally developed by Tichy [1] for impulsive loads to high reduced Reynolds number lubrication in different bearing configurations. Both fluid shear and pressure gradient terms are included in the velocity profiles across the lubricant film. The incompressible continuity equation and Navier Stokes equations, including the temporal inertia term, are simplified using an averaged velocity approach to obtain an extended form of Reynolds equation which applies to both laminar and turbulent flow. All terms in the Navier Stokes equation, including both the convective and temporal inertia terms are included in the analysis. The inclusion of the temporal inertia term creates a fluid acceleration term in the extended Reynolds equation. A primary advantage of this formulation is that fluid film bearings lubricated with low viscosity lubricants which are subject to high force slew rates can be analyzed with this extended Reynolds equation. A short bearing form of the extended Reynolds equation is developed with appropriate boundary conditions. A full kinematic analysis of the short journal bearing is developed including time derivatives up to and including shaft accelerations. Linearized stiffness, damping and mass coefficients are developed for a plain short journal bearing. A time transient solution is developed for the pressure and bearing loads in plain journal bearings supporting a symmetric rigid rotor when the rotor is subjected to rapidly applied large forces. The change in the rotor displacements when subjected to unbalance forces is explored. Several comparisons between conventional Reynolds equation solutions and the extended Reynolds number form with temporal inertia effects will be presented and discussed.

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.

scholarly journals An Analytical Method for the Determination of Temperature Distribution in Short Journal Bearing Oil Film

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 539
Author(s):  
Nebojsa Nikolic ◽  
Zivota Antonic ◽  
Jovan Doric ◽  
Dragan Ruzic ◽  
Stjepan Galambos ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Oil Film ◽  
Symmetric Geometry ◽  
Experimental Values ◽  
Operating Regimes ◽  
Level Of Agreement

The aim of this paper is to derive an equation for the temperature distribution in journal bearing oil film, in order to predict the thermal load of a bearing. This is very important for the prevention of critical regimes in a bearing operation. To achieve the goal, a partial differential equation of the temperature field was first derived, starting from the energy equation coupled with the Reynolds equation of hydrodynamic lubrication for a short bearing of symmetric geometry. Then, by solving the equation analytically, the function of temperature distribution in the bearing oil film has been obtained. The solution is applied to the journal bearing, for which the experimental data are available in the references. Finally, the obtained results have been compared to the corresponding experimental values for two operating regimes, and a good level of agreement was achieved.

Empirical Treatment of Hydrodynamic Journal Bearing Performance in the Superlaminar Regime

1970 ◽  
Vol 12 (2) ◽  
pp. 116-122 ◽  
Author(s):  
H. F. Black
Keyword(s):  
Reynolds Number ◽  
Field Equation ◽  
Experimental Work ◽  
Reynolds Equation ◽  
Pressure Field ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Theoretical Treatment ◽  
Hydrodynamic Journal Bearing

The application of a perturbation in terms of simple correlations for friction in turbulent Couette and ‘screw’ flows, together with a further empirical assumption consonant with the experimental work of Smith and Fuller (1), leads to a pressure field equation identical in form with the Reynolds equation. The load capacity of journal bearings throughout most of the superlaminar range may be represented by a single curve, and existing laminar solutions may be applied with the parameters modified by Reynolds number. The theory is compared with published experimental results, and with the most successful theoretical treatment (4). The correlations obtained confirm the adequacy of the theory to predict performance in the superlaminar régime.

scholarly journals Numerical Investigation of Pressure Profile in Hydrodynamic Lubrication Thrust Bearing

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Farooq Ahmad Najar ◽  
G. A. Harmain
Keyword(s):  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Pressure Profile ◽  
Grid Refinement ◽  
Average Value ◽  
Lubricant Oil ◽  
Pressure Profiles ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Grid Independence

Reynolds equation is solved using finite difference method (FDM) on the surface of the tilting pad to find the pressure distribution in the lubricant oil film. Different pressure profiles with grid independence are described. The present work evaluates pressure at various locations after performing a thorough grid refinement. In recent similar works, this aspect has not been addressed. However, present study shows that it can have significant effect on the pressure profile. Results of a sector shaped pad are presented and it is shown that the maximum average value of pressure is 12% (approximately) greater than the previous results. Grid independence occurs after 24 × 24 grids. A parameter “ψ” has been proposed to provide convenient indicator of obtaining grid independent results. ψ=|(Prefinedgrid-PRefrence-grid)/Prefinedgrid|, ψ≤ε, where “ε” can be fixed to a convenient value and a constant minimum film thickness value of 75 μm is used in present study. This important parameter is highlighted in the present work; the location of the peak pressure zone in terms of (r,θ) coordinates is getting shifted by changing the grid size which will help the designer and experimentalist to conveniently determine the position of pressure measurement probe.

A Contribution to the Analysis of the Thermo-Hydrodynamic Lubrication of Porous Self-Lubricating Journal Bearings

2010 ◽  
Vol 297-301 ◽  
pp. 618-623 ◽  
Author(s):  
S. Boubendir ◽  
Salah Larbi ◽  
Rachid Bennacer
Keyword(s):  
Thermal Effects ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Governing Equations ◽  
Hydrodynamic Analysis ◽  
Result Show

In this work the influence of thermal effects on the performance of a finite porous journal bearing has been investigated using a thermo-hydrodynamic analysis. The Reynolds equation of thin viscous films is modified taking into account the oil leakage into the porous matrix, by applying Darcy’s law to determine the fluid flow in the porous media. The governing equations were solved numerically using the finite difference approach. Obtained result show a reduction in the performance of journal bearings when the thermal effects are accounted for and, this reduction is greater when the load capacity is significant.

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