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.

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.

A Theory of Mixed Lubrication

1972 ◽  
Vol 186 (1) ◽  
pp. 421-430 ◽  
Author(s):  
H. Christensen
Keyword(s):  
Hydrodynamic Lubrication ◽  
Dynamic Properties ◽  
Mixed Lubrication ◽  
Rapid Rise ◽  
Operating Characteristics ◽  
Lubrication Regime ◽  
Lubricated Contact ◽  
Mixed Lubrication Regime ◽  
Lubrication Conditions ◽  
Lubrication Properties

The phenomena observed when a lubricated contact or bearing is operating under mixed lubrication conditions are assumed to arise from an interaction of the surface asperities or roughness as well as from hydro-dynamic action of the sliding surfaces. It is shown how one of the previously published stochastic models of hydrodynamic lubrication can be extended or generalized to deal with mixed lubricating conditions. As an illustration of the application of the theory to a concrete example the influence on the operating characteristics of a plane pad, no side-leakage bearing is analysed. It is found that in the mixed lubrication regime friction is mainly controlled by the boundary lubrication properties of the liquid–solid interface. Load, on the other hand, is almost entirely controlled by the hydro-dynamic properties of the bearing. It is demonstrated how transition to mixed lubrication conditions will cause a rapid rise in friction thereby producing a minimum point in the Stribeck type diagram.

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.

A Performance Prediction of Microgrooved Bearings Under Mixed Lubrication

2008 ◽  
Author(s):  
Katsuhiro Ashihara ◽  
Hiromu Hashimoto
Keyword(s):  
Film Thickness ◽  
Contact Pressure ◽  
Hydrodynamic Lubrication ◽  
Calculation Model ◽  
Mixed Lubrication ◽  
Severe Condition ◽  
Oil Film ◽  
Precise Prediction ◽  
Lubrication Condition ◽  
Bearing Alloy

In the designs and analysis of engine bearings for automobiles, the precise prediction of the lubrication condition in severe condition is important. In the mixed-elasto-hydrodynamic lubrication analysis, the contact between the projections of surface roughness distributed stochastically is usually considered. This paper describes a theoretical model under the mixed lubrication in the microgrooved bearing. In this modeling, it is assumed that the section shape of microgrooved bearing alloy takes the circular arc form. In the part where contact is caused, the contact pressure is calculated by the Hertzian equation. The elastic deformation of the bearing by the mixed pressure with which oil film pressure and contact pressure are mixed by each allotment ratio is considered. Moreover, the balance requirement between the sum total of mixed pressure on bearing surface and the journal load is met. Under such an assumption, the numerical calculation model is newly obtained to predict the bearing performance in the mixed lubrication of microgrooved bearing. The numeric solutions of EHL based on the mixed lubrication are compared with EHL based on the fluid lubrication. The predicted oil film thickness at the center of bearing by the mixed lubrication model is remarkably thin compared with that by the fluid lubrication model. This shows that the load ability of the oil film thickness decreases by generating contact.

Lubrication Phenomena in Spur Gears: Capacity, Film Thickness Variation, and Efficiency

1965 ◽  
Vol 87 (3) ◽  
pp. 655-663 ◽  
Author(s):  
R. Wayne Adkins ◽  
E. I. Radzimovsky
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Power Loss ◽  
Hydrodynamic Lubrication ◽  
Thickness Variation ◽  
Spur Gears ◽  
Oil Film ◽  
Lubrication Conditions ◽  
Lubricant Viscosity

In this paper the oil film separating the mating surfaces of involute spur gears operating under hydrodynamic lubrication conditions is analyzed. This analysis surpasses previous analyses in as much as the actual motion of the involute profiles (rolling, sliding, and squeezing motion) and the total number of teeth engaged at any one time are considered. Expressions are derived for the pressure distribution, shear stress, and power loss in the oil film at any phase of tooth engagement. A method is developed by which these expressions can be applied to determine the film thickness at any instant and the power loss for a given load, speed, and lubricant viscosity.

The comprehensive effect of surface texture and roughness under hydrodynamic and mixed lubrication conditions

2017 ◽  
Vol 231 (10) ◽  
pp. 1307-1319 ◽  
Author(s):  
Chenbo Ma ◽  
Yanjun Duan ◽  
Bo Yu ◽  
Jianjun Sun ◽  
Qiaoan Tu
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Diameter Ratio ◽  
Mixed Lubrication ◽  
Textured Surface ◽  
Texture Parameters ◽  
Lubrication Condition ◽  
Lubrication Conditions ◽  
Effect Of Surface

A theoretical study is carried out to investigate the comprehensive effect of the machined roughness and fabricated textures, by solving the average Reynolds equation coupled with a mass-conservative cavitation algorithm and taking into account asperity contact. We analyzed the influence of surface roughness, which is represented by the combined root-mean-square roughness σ and surface pattern parameter γ on the optimum texture parameters including the dimple depth-over-diameter ratio and area density under hydrodynamic and mixed lubrication conditions. The results show that the effect of surface roughness on load-carrying capacity can be ignored under hydrodynamic lubrication condition. Furthermore, the optimum texture parameters under hydrodynamic lubrication condition and the optimum dimple depth-over-diameter ratio under mixed lubrication condition are determined at minimized friction coefficient, which can be taken as the same for smooth-textured surface and rough-textured surface. The corresponding minimum friction coefficient increases with increasing σ and γ, and decreasing dimple area density under mixed lubrication condition.

Analysis of Oil-Film Pressure Distribution in Porous Journal Bearings Under Hydrodynamic Lubrication Conditions Using an Improved Boundary Condition

1997 ◽  
Vol 119 (1) ◽  
pp. 171-178 ◽  
Author(s):  
Satoru Kaneko ◽  
Yuji Hashimoto ◽  
Hiroki I
Keyword(s):  
Boundary Condition ◽  
Hydrodynamic Lubrication ◽  
Angular Position ◽  
Momentum Equation ◽  
Film Pressure ◽  
Oil Film ◽  
Pressure Distributions ◽  
Lubrication Conditions ◽  
Oil Film Pressure ◽  
Negative Film

Pressure distributions in the oil film of a porous journal bearing are investigated theoretically and experimentally under hydrodynamic lubrication conditions. The circumferential boundary condition for the oil-film pressure is obtained by applying an integral momentum equation to the oil-film region in the bearing clearance. The oil-film pressure distributions are numerically solved using this momentum equation and taking into consideration the balance between oil fed into the clearance and that lost from it. The present analysis shows the occurrence of a negative film pressure before the trailing end of the oil-film region. The experimental results confirm the existence of this negative film pressure. Furthermore, the angular position of the trailing end of the oil-film region obtained in the present analysis moves toward the downstream region, yielding better agreement with the measured and calculated film regions than was found in our previous analysis based on the quasi-Reynolds boundary condition.

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.

Piston ring-cylinder liner tribology investigation in mixed lubrication regime: part I-correlation with bench experiment

2015 ◽  
Vol 67 (6) ◽  
pp. 520-530 ◽  
Author(s):  
Lin Ba ◽  
Zhenpeng He ◽  
Lingyan Guo ◽  
Young Chiang ◽  
Guichang Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Sudden Change ◽  
Mixed Lubrication ◽  
Friction Reduction ◽  
Asperity Contact ◽  
Film Rupture ◽  
Frictional Loss ◽  
Content Type ◽  
Oil Film ◽  
Ring Sample

Purpose – The purpose of this paper is to improve the environment and save energy, friction reduction, lower oil consumption and emissions demand that are the chief objectives of the automotive industry. The piston system is the largest frictional loss source, which accounts for about 40 per cent of the total frictional loss in engine. In this paper, the reciprocating tribometer, which is updated, was used to evaluate the friction and wear performances. Design/methodology/approach – An alternate method is introduced to investigate the effect of reciprocating speed, normal load, oil pump speed and ring sample and oil temperature on friction coefficient with the ring/liner of a typical inline diesel engine. The orthogonal experiment is designed to identify the factors that dominate wear behavior. To understand the correlations between friction coefficients and wear well, different friction coefficient results were compared and explained by oil film build-up and asperity contact theory, such as the friction coefficient over a long period and averaged the friction coefficient over one revolution. Findings – The friction coefficient changes little but fluctuates with a small amplitude in the stable stage. The sudden change of frequency, load and stroke will lead to the oil film rupture. The identification for the factors that dominates the wear loss is ranged as F (ring sample) > , E (oil sample) > , B (stroke) > , D (temperature) > , A (load) > , G (liner) > and C (frequency). Originality/value – This paper develops and verifies a methodology capable of mimicking the real engine behavior at boundary and mixed lubrication regimes which can minimize frictional losses, wear, reduce much work for the experiment and reduce the cost. The originality of the work is well qualified, as very few papers on a similar analysis have been published, such as: The friction coefficient values fluctuating in the whole stage may be caused by the vibration of the system; suddenly, boundary alternation may help the oil film to form the lubrication; and weight loss mainly comes from the contribution of the friction coefficient value fluctuation. The paper also found that the statistics can gain more information from less experiment time based on a design of experiment.

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