A Study of the Mechanism of Lubrication in Porous Journal Bearings: Effects of Dimensionless Oil-Feed Pressure on Static Characteristics Under Hydrodynamic Lubrication Conditions

1994 ◽  
Vol 116 (3) ◽  
pp. 606-611 ◽  
Author(s):  
Satoru Kaneko ◽  
Yasuhiro Ohkawa ◽  
Yuji Hashimoto
Keyword(s):  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Static Characteristics ◽  
Oil Film ◽  
Bearing Clearance ◽  
Feed Pressure ◽  
Angular Extent ◽  
Lubrication Conditions

The static characteristics of porous journal bearings under hydrodynamic lubrication conditions are theoretically investigated assuming that the oil is fed through their outside diameters under a small pressure. The angular extent of the oil film formed in the bearing clearance is numerically solved on the basis of the following postulate: when the oil film extent reaches steady state, the inflow of oil into the bearing clearance through the porous matrix due to the oil-feed pressure must make up for the oil leakage from the ends through the clearance gap and that into the porous matrix due to the hydrodynamic pressure in the film. Numerical results show that the dimensionless oil-feed pressure significantly influences the static characteristics. Experiments are also conducted for confirmation after the theoretical examination.

Experimental Investigation of Mechanism of Lubrication in Porous Journal Bearings: Part 1—Observation of Oil Flow in Porous Matrix

1990 ◽  
Vol 112 (4) ◽  
pp. 618-623 ◽  
Author(s):  
S. Kaneko ◽  
S. Obara
Keyword(s):  
Hydrodynamic Lubrication ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Feed Pressure ◽  
Glass Spheres ◽  
Load Line ◽  
Oil Flow ◽  
Uniform Diameter ◽  
Lubrication Conditions ◽  
Oil Film Pressure

The oil flow in the porous matrix is experimentally investigated to explicate the mechanism of lubrication in the porous journal bearings. To visualize the flow in the porous matrix, a simplified model is used for the test bearing, whose matrix is composed of packed glass spheres having small uniform diameter. A dye-injection method is used for visualization. It is observed that there exists a circulation of oil through the porous matrix and this flow contributes to the lubrication in the porous bearings. The flow pattern is dependent on the lubrication conditions. Under hydrodynamic lubrication conditions, the oil in the porous matrix flows away from the position of the load line towards the unloaded region. However under boundary lubrication conditions, when the oil feed pressure is negligibly small, most of the oil in the porous matrix flows toward the region where the oil film pressure would take the minimum.

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.

Static Characteristics of Journal Bearings With Square Dimples

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Hiroo Taura ◽  
Satoru Kaneko
Keyword(s):  
Hydrodynamic Lubrication ◽  
Numerical Models ◽  
Experimental Studies ◽  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Conditions ◽  
Static Characteristics ◽  
Lubrication Performance

Surface texturing is a technique for improving frictional and hydrodynamic performances of journal bearings because microtextures can serve as reservoirs for oil or traps for debris and may also generate hydrodynamic pressure. Over the past two decades, many researchers have experimentally demonstrated that texturing of various tribological elements can reduce friction force and wear, contributing to improvement of lubrication performance. Some numerical studies have examined the hydrodynamic lubrication conditions and reported that surface texturing affects the static characteristics of journal bearings, such as their load carrying capacity and friction torque. However, the validity of these numerical models has not been confirmed because of a lack of experimental studies. This study proposes a numerical model that includes both inertial effects and energy loss at the edges of dimples on the surface of a journal bearing in order to investigate the bearing's static characteristics. Experimental verification of journal bearings is also conducted with a uniform square-dimple pattern on their full-bearing surface. The results obtained by the model agree well with those of experiment, confirming the model's validity. These results show that under the same operating conditions, textured bearings yield a higher eccentricity ratio and lower attitude angle than the conventional ones with a smooth surface. This tendency becomes more marked for high Reynolds number operating conditions and for textured bearings with a large number of dimples.

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.

scholarly journals A Method for Monitoring Lubrication Conditions of Journal Bearings in a Diesel Engine Based on Contact Potential

2020 ◽  
Vol 10 (15) ◽  
pp. 5199
Author(s):  
Biao Wan ◽  
Jianguo Yang ◽  
Sicong Sun
Keyword(s):  
Diesel Engine ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Asperity Contact ◽  
Contact Potential ◽  
Axis Orbit ◽  
Lubrication Condition ◽  
The Relationship ◽  
Lubrication Conditions

Wear of the journal bearings in a diesel engine is usually caused by asperity contact. Increased contact potential is caused by the asperity contact between the journal bearing and the shell. This paper analyzes the relationship between the contact potential and asperity contact and presents a method based on contact potential to monitor the bearing wear caused by asperity contact. A thermo-elastic hydrodynamic lubrication (THL) model of the journal bearing on the test bench was established and was verified by measuring its axis orbit. The asperity contact proportion was calculated based on this THL model, and its relationship with the measured contact potential was determined. The main contribution of this paper is to present a new method for monitoring the lubrication conditions of journal bearings in a diesel engine based on contact potential. The results showed that (a) when the minimum oil film thickness was less than 5 μm, asperity contact occurred between the bearing shell and the journal, which led to a sharp increase in contact pressure and a rapid increase in friction power consumption. Further, (b) there was a positive correlation between contact potential and asperity contact. The contact potential was greater than 0.75 mv when asperity contact occurred. These results proved that asperity contact could be accurately monitored using the contact potential, and the feasibility of using the contact potential to monitor the lubrication condition of a bearing was verified.

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.

scholarly journals The effect of oil feeding type and oil grade on the oil film bearing capacity

2021 ◽  
Vol 23 (2) ◽  
pp. 381-386
Author(s):  
Aleksander Mazurkow ◽  
Waldemar Witkowski ◽  
Adam Kalina ◽  
Bartłomiej Wierzba ◽  
Mariusz Oleksy
Keyword(s):  
Bearing Capacity ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Static Characteristics ◽  
Oil Film ◽  
Feeding Type ◽  
Oil Flow ◽  
Minimum Height ◽  
Face Side

Two types of hydrodynamically lubricated plain journal bearings were subject to examination differing in the method used to feed them with oil. The first type was fed from a lubrication pocket and the second from the bearing face side. Mathematical models were developed with two-way oil flow allowing to determine the oil film bearing capacity, the maximum pressure, the maximum temperature, and the film oil minimum height for given position of journal relative to solid bush. Static characteristics were developed used in the further course of the study to compare operating parameters of the considered types of bearings. Another issue considered in the paper is the effect of oil VG grade on bearing performance with conditions of oil feeding taken into account and results of the research presented.

Surface Finish and Clearance Effects on Journal-Bearing Load Capacity and Friction

1959 ◽  
Vol 81 (2) ◽  
pp. 245-252 ◽  
Author(s):  
F. W. Ocvirk ◽  
G. B. DuBois
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Surface Finish ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Oil Film ◽  
Bearing Clearance ◽  
Bearing Load

A method of relating surface finish to minimum oil-film thickness and the corresponding load capacity of plain journal bearings is presented with supporting experimental data. The effect of clearance on load capacity and friction are shown on graphs indicating an optimum bearing clearance.

Sign in / Sign up

Export Citation Format

Share Document