Generalized Reynolds Equation for Micropolar Fluid With Microrotations Near Surface and Its Application to Journal Bearings

1994 ◽  
Vol 116 (3) ◽  
pp. 654-657 ◽  
Author(s):  
N. M. Bessonov
Keyword(s):  
Friction Surface ◽  
Effective Viscosity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Thin Layers ◽  
Near Surface ◽  
Generalized Reynolds Equation ◽  
Micropolar Liquid

The theory of micropolar liquid lubrication (see Prakash and Sinha, 1975; Tipei, 1979; Singh and Sinha, 1982) takes into account only the increasing of effective viscosity in thin layers. Modern experiments (see Derjaguin et al., 1985) show that effective viscosity can increase or decrease and approaches to a certain limit (boundary viscosity), depending on the type of liquid and nature of the solid surface. A new generalized Reynolds equation that takes into account both these effects and also all possible situations in microrotation near the friction surface is derived in this work. An example using the equation for calculation of the journal bearing performance is given. It is shown that the friction coefficient can be sufficiently decreased without a noticeable change in the load capacity by regulation of interaction between micropolar lubricant and surfaces.

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.

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.

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.

Dynamic Loading of Micropolar Fluid Lubricated Short Journal Bearings

1981 ◽  
Vol 23 (1) ◽  
pp. 37-44
Author(s):  
C. Singh ◽  
P. Sinha
Keyword(s):  
Micropolar Fluid ◽  
Effective Viscosity ◽  
Reynolds Equation ◽  
Dynamic Behaviour ◽  
Journal Bearing ◽  
Constant Load ◽  
Journal Bearings ◽  
Detailed Consideration ◽  
Dynamically Loaded ◽  
Sinusoidal Load

Dynamically loaded bearings in which the load alternates or rotates are studied in this paper. The Reynolds equation for the general case of a dynamically loaded infinitely short bearing is derived, where the lubricant is assumed to be micropolar. Detailed consideration is given to the dynamic behaviour of squeeze films in a short journal bearing under a sinusoidal load with no journal rotation. Various bearing characteristics are calculated, assuming a full film to exist. The micropolarity of the fluid results in more resistance to journal motion, thereby allowing smaller eccentricities for a constant load. The overall conclusion of this study is an increase in the effective viscosity due to the micropolarity of the lubricant. This theory may find application in lubrication when additives are used.

The Load Capacity of Short Journal Bearings With Oscillating Effective Speed

1964 ◽  
Vol 86 (2) ◽  
pp. 348-353 ◽  
Author(s):  
B. K. Gupta ◽  
R. M. Phelan
Keyword(s):  
Significant Contribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Load Capacity ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Major Conclusion ◽  
Angular Velocities ◽  
Effective Speed

The development of the Reynolds equation for the general case of dynamically loaded journal bearings is extended to include the concept of an effective speed that combines in one term the angular velocities of the journal, bearing, and load. Numerical solutions for the short-bearing approximation are presented for the case of an oscillating effective speed and a load that is constant or varying sinusoidally. Results are compared with available experimental data. The major conclusion is that for those cases involving an oscillating effective speed and a reversing load, the only significant contribution to load capacity comes from the squeeze film and the wedge film can safely be ignored when designing such bearings.

A Thermohydrodynamic Coupling Model of Oil Aeration Turbulent Lubrication for Journal Bearing With Interface Effect

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Xiaohui Lin ◽  
Shuyun Jiang ◽  
Chengyu Hua ◽  
Feng Cheng
Keyword(s):  
Velocity Distribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Coupling Model ◽  
Wall Turbulence ◽  
Volume Distribution ◽  
Bubble Volume ◽  
Coupled Equations ◽  
Generalized Reynolds Equation

Oil aeration lubricant in high-speed journal bearing is composed of mixture of continuous phase liquid and discrete phase bubbles. This work establishes a thermohydrodynamic (THD) coupling model for this lubrication condition. The generalized Reynolds equation is derived by the continuity equation, Navier–Stokes equation, law of wall turbulence model, and bubble volume distribution function, and then a THD oil aeration turbulent lubrication model is established by coupling the generalized Reynolds equation, energy equation, force equilibrium equation of bubble, and population balance equations (PBEs). The coupled-equations are solved numerically to obtain the pressure distribution under oil aeration lubrication state, the equilibrium distribution of bubble volume, the turbulent velocity distribution, the bubble velocity distribution, and the temperature rise. The results show that the load capacity of a bearing with oil aeration lubrication model is higher than that of the same bearing with a pure oil lubrication model, and heat dissipation performance of the bearing under the oil aeration lubrication state is superior.

Spiral Bearing Lubrication with Viscosity Variation And Thermal Effect of Two Layer Fluid

2017 ◽  
Vol 6 (5) ◽  
Author(s):  
M. Ganapathi ◽  
S. Vijayakumarvarma ◽  
K.R.K. Prasad ◽  
Bharath Kumar
Keyword(s):  
Thermal Effect ◽  
Layer Thickness ◽  
Coefficient Of Friction ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Load Factor ◽  
Load Pressure ◽  
Viscosity Variation ◽  
Generalized Reynolds Equation

In this paper a fluid film equation for two layer fluids and generalized Reynolds equation for convergent and divergent spiral bearing is derived with thermal effect. It is applied to see the effect of pre-load factor, viscosity variation, eccentricity, peripheral layer thickness. Expressions for load, pressure and coefficient of friction are derived and are analyzed numerically. The effect of pre-load factor analyzed for convergent and divergent spiral bearings. When pre-load factor is zero then both convergent and divergent spiral bearings are becomes journal bearing. It is observed the dimensionless load capacity values form the tables. The spiral bearing bears more load capacity than journal bearing. The effects of viscosity variation and thermal effect on these parameters are also analyzed.

Characteristics of Micro Gas Journal Bearings Based on Effective Viscosity

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Haijun Zhang ◽  
Changsheng Zhu ◽  
Qin Yang
Keyword(s):  
Knudsen Number ◽  
Effective Viscosity ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Journal Bearings ◽  
Eccentricity Ratio ◽  
Rarefied Flow ◽  
Attitude Angle ◽  
Modified Reynolds Equation ◽  
Bearing Number

According to the first order slip velocity boundary, a modified Reynolds equation for micro gas journal bearings is presented with consideration of effective viscosity under a rarefied flow condition. A modified Reynolds equation is attained and solved using the finite difference method. The nondimensional pressure, load capacity, and attitude angle for micro gas journal bearings under different reference Knudsen numbers (the ratio of ambient molecular mean free path to the average radial clearance), bearing numbers, and eccentricity ratios are obtained. The numerical analysis demonstrates that the slip model with effective viscosity is in a better agreement with the FK model derived by Fukui and Kaneko than that without effective viscosity. When the bearing number is constant, the pressure and load capacity decrease, and the attitude angle changes inversely with the increasing reference Knudsen number. The larger the eccentricity ratio, the larger change in attitude angle from effective viscosity. When eccentricity ratio is less than 0.6, the attitude angle changes softly, and the effect of effective viscosity is unobvious. When the eccentricity ratio is constant, the influence of effective viscosity on nondimensional load capacity and attitude angle becomes larger with the increasing bearing number, and the influence is more prominent with a larger reference Knudsen number.

scholarly journals Surface roughness effect on thermohydrodynamic analysis of journal bearings lubricated with couple stress fluids

2019 ◽  
Vol 8 (1) ◽  
pp. 397-406 ◽  
Author(s):  
Vishwanath B. Awati ◽  
Ashwini Kengangutti
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Reynolds Equation ◽  
Multigrid Method ◽  
Energy Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Roughness Effect ◽  
Hydrodynamic Analysis

Abstract The paper presents, surface roughness effect for thermo-hydrodynamic analysis of journal bearings extended to couple stress lubricants with high polymer additives. A modified energy equation is simultaneously solved with heat transfer equation as well as modified Reynolds equation by using Multigrid method. The effects of couple stress and surface roughness on the performances of a finite journal bearing are presented in detail. Further, it is shown that lubricants with couple stress and surface roughness, not only increases the load capacity and decreases the friction coefficient, but also generates a lower bearing temperature field. Thus, the lubricant with couple stress improves the performance of journal bearings. The characteristics of bearing are compared with numerical results.

Dynamic Characteristic of Multirecess Externally Pressurized Oil Journal Bearing

1978 ◽  
Vol 100 (4) ◽  
pp. 467-471 ◽  
Author(s):  
M. K. Ghosh
Keyword(s):  
Perturbation Theory ◽  
Theoretical Analysis ◽  
Dynamic Characteristic ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Harmonic Vibrations ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Generalized Reynolds Equation

This paper describes a theoretical analysis of the dynamic behavior of multirecess externally pressurized oil journal bearings for a nonrotating journal subjected to plane harmonic vibrations. The generalized Reynolds’ equation for a finite bearing has been solved using perturbation theory. Stiffness and damping characteristics of a capillary compensated bearing are given.

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