A Sommerfeld Solution for Finite Bearings With Circumferential Grooves

1960 ◽  
Vol 82 (2) ◽  
pp. 321-326 ◽  
Author(s):  
J. V. Fedor
Keyword(s):  
Differential Equation ◽  
Excellent Agreement ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Algebraic Complexity ◽  
Eccentricity Ratio ◽  
Finite Form ◽  
Oil Film ◽  
Method Of Solution ◽  
Friction Curve

A method of solution is developed that circumvents the algebraic complexity in the solution of Reynolds differential equation applied to full journal bearings. The method leads to equations for journal-bearing characteristics that are in finite form. Salient features of the complete-oil-film solution are: As the eccentricity ratio b approaches 1, the load capacities of all finite bearings approach that of the infinite bearing; also, the friction curve intercept, (r/c)f, is 1 for all finite bearings when b equals 1. Results are compared with calculated values published by Muskat and Morgan for 0 < b < 0.6. Excellent agreement is found throughout the compared range.

Thermohydrodynamic Lubrication Analysis of Misaligned Plain Journal Bearing With Rough Surface

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Jun Sun ◽  
Mei Deng ◽  
Yonghong Fu ◽  
Changlin Gui
Keyword(s):  
Surface Roughness ◽  
Thermal Effect ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Eccentricity Ratio ◽  
Oil Viscosity ◽  
Oil Film ◽  
Lubrication Performance ◽  
Journal Misalignment

Journal misalignment exists generally in journal bearings. When severe journal misalignment takes place, the minimum film thickness of journal bearings reduces greatly. In this condition, the surface roughness, the oil viscosity-pressure relationship (VPR), and the thermal effect have obvious effects on hydrodynamic lubrication performance of misaligned bearings. In this paper, the oil film pressure, oil film temperature, load-carrying capacity, end leakage flow rate, frictional coefficient, and misalignment moment of a journal bearing with different angles of journal misalignment and surface roughness, and considering oil VPR and thermal effect, were calculated based on the generalized Reynolds equation, energy equation, and solid heat conduction equation. The results show that the oil VPR and surface roughness have a significant effect on the lubrication of misaligned journal bearings under large eccentricity ratio. The thermal effect will affect obviously the lubrication of misaligned journal bearings when eccentricity ratio and angle of journal misalignment are all large. In the present design, the size of the journal bearing is compact more and more, and the eccentricity ratio and angle of journal misalignment are usually large in operating conditions. Therefore, it is necessary to take the effects of journal misalignment, surface roughness, oil VPR, and thermal effect into account in the design and analyses of journal bearings.

Characteristics of Herringbone-Grooved, Gas-Lubricated Journal Bearings

1965 ◽  
Vol 87 (3) ◽  
pp. 568-576 ◽  
Author(s):  
J. H. Vohr ◽  
C. Y. Chow
Keyword(s):  
Differential Equation ◽  
Journal Bearing ◽  
Groove Depth ◽  
Radial Force ◽  
Journal Bearings ◽  
Speed Ratio ◽  
Plain Bearing ◽  
Relative Speed ◽  
Whirl Speed ◽  
Limiting Case

A differential equation is obtained for the smoothed “overall” pressure distribution around a herringbone-grooved, gas-lubricated journal bearing operating with a variable film thickness. The equation is based on the limiting case of an idealized bearing for which the number of grooves approaches an infinite number. A numerical solution to the differential equation is obtained valid for small eccentricities. This solution includes the case where the journal is undergoing steady circular whirl. In addition to the usual plain bearing parameters L/D, Λ, and whirl speed ratio ω3/(ω1 + ω2), the behavior of a grooved bearing also depends on four additional parameters: The groove angle β, the relative groove width α, the relative groove depth H0, and a compressibility number, Λs, which is based on the relative speed between the grooved and smooth members of the bearing. Results are presented showing bearing radial force and attitude angle as functions of β, α, H0, Λs, Λ, and whirl speed ratio.

A Design of Coverage Area for Textured Surface of Sliding Journal Bearing Based on Genetic Algorithm

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Hui Zhang ◽  
Mahshid Hafezi ◽  
Guangneng Dong ◽  
Yang Liu
Keyword(s):  
Genetic Algorithm ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Textured Surface ◽  
The Novel ◽  
Eccentricity Ratio ◽  
Coverage Area ◽  
Elliptical Shape ◽  
Bearing Load ◽  
Rectangular Grids

This paper aims to improve the tribological performance of journal bearings by optimizing the coverage area of circular microtextures in divergent region of the sleeve. A numerical model is proposed to calculate the friction coefficient and bearing load of textured journal bearings. The surface of the sleeve is divided into rectangular squares. Textures that located at the center of rectangular grids are assumed to be present or absent, marked as 1 and 0, respectively. Afterward, different texture coverage area arrangements are evolved and selected based on the genetic algorithm (GA). The area of semi-elliptical shape is obtained as the novel and preferable textured coverage area design for journal bearings. Influences of width and eccentricity ratio are discussed, which confirm the semimajor and semiminor axes of the semi-elliptical shape of texture coverage area equal to one-third of the circumferential length and half of the width of the journal bearing, respectively.

STATIC CHARACTERISTICS OF OFFSET 8-LOBE JOURNAL BEARINGS

Tribologia ◽  
2021 ◽  
Vol 295 (1) ◽  
pp. 39-51
Author(s):  
Stanisław Strzelecki
Keyword(s):  
Laminar Flow ◽  
Equilibrium Position ◽  
Iterative Procedure ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Diameter Ratio ◽  
Static Characteristics ◽  
Oil Film ◽  
Cooling Conditions ◽  
Grinding Machines

The 8-lobe journal bearings have found application in the bearing systems of spindles of grinding machines. The design of bearings and the large number of lobes and oil grooves assures good cooling conditions of bearing. These bearings can be manufactured as the bearings with cylindrical, non-continuous operating surfaces separated by six lubricating grooves, bearings with the pericycloidal shape of the bearing bore, and as offset journal bearing. This paper presents the results of the computation of static characteristics of an offset 8-lobe journal bearing operating under the conditions of an aligned axis of journal and bush, adiabatic oil film, and at the static equilibrium position of journal. Different values of bearing length to diameter ratio, relative clearance, and lobe relative clearance were assumed. Reynolds' energy and viscosity equations were solved by means of an iterative procedure. Adiabatic oil film, laminar flow in the bearing gap, and aligned orientation of journal in the bearing were considered.

Experimentally study of dynamic pressure distribution and oil film forces in journal bearing using ElectroMechanical Film sensor array

2019 ◽  
Vol 234 (4) ◽  
pp. 903-913
Author(s):  
Changmin Chen ◽  
Jianping Jing ◽  
Jiqing Cong ◽  
Chao Ji
Keyword(s):  
Pressure Distribution ◽  
Sensor Array ◽  
Journal Bearing ◽  
Dynamic Pressure ◽  
Vertical Direction ◽  
Journal Bearings ◽  
Film Sensor ◽  
Film Pressure ◽  
Oil Film ◽  
Oil Film Pressure

The acquisition of the oil film pressure and forces on the bearing pads through experimentation is crucial to understanding the characteristics of journal bearing. Lots of efforts had been taken in film pressure measurement, and the pressure was obtained at specified position on the bearing pads. However, due to the space and structure constraint, merely very limited number of the point pressure can be obtained with traditional sensors and acquiring the detail pressure field on whole bearing pad surface is still an open challenge. In this paper, a method based on thin-film sensors technique is proposed and employed to measure the pressure distribution and oil film forces of journal bearings. The measurement is conducted on a cylindrical journal bearing with two axial grooves, and ElectroMechanical Film sensor arrays are designed and laid on the surface of the bearing pads. The oil film pressure is acquired at up to 32 measurement points in total along the bearing pads in both circumference and axial directions. The pressure distribution in a wide rotation speed range is obtained successfully by using fitting algorithm. Furthermore, the oil film forces on horizon and vertical direction are obtained through the integration of the measured pressure filed. The test results prove that it is feasible to measure the oil pressure filed of journal bearings using ElectroMechanical Film piezo-film sensor array.

Power Loss of Tilting 5-Pad Journal Bearing Operating With Turbulent Oil Film

2005 ◽  
Author(s):  
S. Strzelecki
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Heavy Duty ◽  
Safe Operation ◽  
Oil Film ◽  
Full Knowledge

Journal bearings of high speed turbocompressors, compressors and heavy duty high speed turbine gearboxes operate at journal peripheral speeds like 150 m/s. The flow of lubricant in such bearings is not laminar but super laminar or turbulent. It results in the increase in power loss and in the decrease of the bearing stability. The ground for the safe operation of high speed journal bearings at proper oil film temperature and with less power loss is the full knowledge of bearing performances at the turbulent oil film.

The Influence of Fluid Inertia on the Dynamic Properties of Journal Bearings

1975 ◽  
Vol 97 (2) ◽  
pp. 159-165 ◽  
Author(s):  
E. Reinhardt ◽  
J. W. Lund
Keyword(s):  
Journal Bearing ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Graphical Form ◽  
Inertial Forces ◽  
Virtual Mass ◽  
Fluid Inertia ◽  
Eccentricity Ratio ◽  
First Order ◽  
First Order Perturbation

Based on a first-order perturbation solution in a modified Reynolds number an analysis is presented to determine the effect of the fluid film inertial forces on the dynamic properties of a journal bearing. The corrections to the regular amplitude and velocity coefficients are found to be small, but the accompanying acceleration coefficients which may correspond to a virtual mass of several times the mass of the journal itself, could become significant for short rotors. Numerical results are given in graphical form with dimensionless coefficients as functions of the operating eccentricity ratio.

Nonlinear Dynamic Oil-Film Forces in Infinite-Short Journal Bearings

2011 ◽  
Author(s):  
Lihua Yang ◽  
Weimin Wang ◽  
Lie Yu
Keyword(s):  
Nonlinear Dynamic ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Analytic Solutions ◽  
Journal Bearings ◽  
Oil Film ◽  
Dynamic Coefficients ◽  
Representation Model ◽  
Linear And Nonlinear

In this paper, the analytic solutions of oil-film forces in infinite-short cylindrical journal bearing are calculated by solving its corresponding Reynolds equation. On this base, the linear and nonlinear dynamic coefficients of the bearing are predicted. By comparing the dynamic oil-film forces approximately represented by dynamic coefficients with the analytic solutions, the accuracy of this representation model is investigated. The results show that more orders of dynamic coefficients are included in representation model, the obtained approximate oil-film forces are more close to their analytic solutions. This can be a reference to illustrate the feasibility and applicability of representing oil-film forces by applying the dynamic coefficients of bearings.

Stability of Jeffcott Rotor Operating in Tilting 3-Pad Journal Bearings with Turbulent Oil Film

2009 ◽  
Vol 147-149 ◽  
pp. 450-455
Author(s):  
Stanislaw Strzelecki ◽  
Sobhy M. Ghoneam
Keyword(s):  
Theoretical Investigation ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Oil Film ◽  
Temperature Distributions ◽  
Jeffcott Rotor ◽  
Oil Flow ◽  
The Stability ◽  
Oil Film Pressure

This paper introduces the results of theoretical investigation on the dynamic characteristics of tilting 3-pad journal bearing that operates with turbulent oil film. The Reynolds, energy, viscosity and geometry equations determine the oil film pressure, temperature distributions, and oil film resultant force that are the grounds for the dynamic characteristics of bearing. These equations were solved simultaneously on the assumption of adiabatic laminar or adiabatic turbulent oil flow in the bearing gap. The stability and system damping of Jeffcott rotor operating in tilting 3-pad journal bearing was determined.

HYDRODYNAMIC CHARACTERISTICS OF ER FLUID FLOWS IN JOURNAL BEARINGS

2003 ◽  
Vol 17 (01n02) ◽  
pp. 205-208 ◽  
Author(s):  
KE-QIN ZHU ◽  
JIE PENG
Keyword(s):  
Electric Field ◽  
Journal Bearing ◽  
Fluid Flows ◽  
Journal Bearings ◽  
Hydrodynamic Characteristics ◽  
Eccentricity Ratio ◽  
High Eccentricity ◽  
Bingham Plastic ◽  
Er Fluids ◽  
Er Fluid

A numerical analysis is performed on the hydrodynamic characteristics of electrorheological(ER) fluid flows in journal bearings based on the basic hydrodynamic equations. The flow field is assumed to be incompressible and isotropic, the Bingham plastic model is used to describe the behavior of ER fluids. The effect of bearing eccentricity ratio and applied electric field intensity has been studied attentively. It shows that control of the journal bearing through external electric field is much more feasible in high eccentricity ratio bearing than in low eccentricity ratio one.

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