A mixed lubrication analysis of a flat‐land thrust bearing with a surface optimisation method

A numerical method to investigate the mixed lubrication performances of journal-thrust coupled bearings

Industrial Lubrication and Tribology ◽

10.1108/ilt-02-2019-0063 ◽

2019 ◽

Vol 71 (9) ◽

pp. 1099-1107

Author(s):

Guo Xiang Guo Xiang ◽

Yanfeng Han ◽

Renxiang Chen ◽

Jiaxu Wang Jiaxu Wang ◽

Ni Xiaokang

Keyword(s):

Thrust Bearing ◽

Load Capacity ◽

Elastohydrodynamic Lubrication ◽

Hydrodynamic Pressure ◽

Mixed Lubrication ◽

Hydrodynamic Effect ◽

Asperity Contact ◽

Content Type ◽

Lubrication Regime ◽

Coupled Effect

Purpose This paper aims to present a numerical model to investigate the mixed lubrication performances of journal-thrust coupled bearings (or coupled bearings). Design/methodology/approach The coupled hydrodynamic effect (or coupled effect) between the journal and the thrust bearing is considered by ensuring the continuity of the hydrodynamic pressure and the flow field at the common boundary. The mixed lubrication performances of the coupled bearing are comparatively studied for the cases of considering and not considering coupled effect. Findings The simulated results show that the hydrodynamic pressure distributions for both the journal and thrust bearing are modified due to the coupled effect. The decreased load capacity of the journal bearing and the increased load capacity of the thrust bearing can be observed when the coupled effect is considered. And the coupled effect can facilitate in reducing the asperity contact load for both the journal and thrust bearing. Additionally, the interaction between the mixed lubrication behaviors, especially for the friction coefficient, of the journal and the thrust bearing is significant in the elastohydrodynamic lubrication regime, while it becomes weak in the mixed lubrication regime. Originality/value The developed model can reveal the mutual effects of the mixed lubrication behavior between the journal and the thrust bearing.

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Numerical Investigation on the Mixed Lubrication Performance of Water-Lubricated Coupled Journal and Thrust Bearings

Volume 10: 2019 International Power Transmission and Gearing Conference ◽

10.1115/detc2019-97234 ◽

2019 ◽

Author(s):

Yanfeng Han ◽

Guo Xiang ◽

Jiaxu Wang

Keyword(s):

Friction Coefficient ◽

Film Thickness ◽

Thrust Bearing ◽

Journal Bearing ◽

Load Capacity ◽

Hydrodynamic Pressure ◽

Mixed Lubrication ◽

Eccentricity Ratio ◽

Thrust Bearings ◽

Lubrication Performance

Abstract The mixed lubrication performance of water-lubricated coupled journal and thrust bearing (simplified as coupled bearing) is investigated by a developed numerical model. To ensure the continuity of hydrodynamic pressure and flow at the common boundary between the journal and thrust bearing, the conformal transformation is introduced to unify the solution domain of the Reynolds equation. In the presented study, the coupled effects between the journal and thrust bearing are discussed. The effects of the thrust bearing geometric film thickness on the mixed lubrication performance, including the load capacity, contact load and friction coefficient, of the journal bearing are investigated. And the effects of the journal bearing eccentricity ratio on the mixed lubrication performance of the thrust bearing are also investigated. The simulated results indicate the mutual effects between the journal and thrust bearing cannot be ignored in the coupled bearing system. The increasing thrust bearing geometric film thickness generates a decrease in load capacity of journal bearing. There exists an optimal eccentricity ratio of journal bearing that yields the minimum friction coefficient of the thrust bearing.

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A mixed lubrication analysis of a thrust bearing with fractal rough surfaces

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650119867242 ◽

2019 ◽

Vol 234 (4) ◽

pp. 608-621

Author(s):

Xiaohan Zhang ◽

Yang Xu ◽

Robert L Jackson

Keyword(s):

Fractal Dimension ◽

Roughness Length ◽

Thrust Bearing ◽

Rough Surfaces ◽

Mixed Lubrication ◽

Bearing Surface ◽

Fractal Surfaces ◽

Lubrication Regime ◽

Surface Data ◽

Mixed Lubrication Regime

Fractal descriptions of rough surfaces are widely used in tribology. The fractal dimension, D, is an important parameter which has been regarded as instrument and scale independent, although recent findings bring this into question. A thrust bearing is analyzed in the mixed lubrication regime while considering the fractal nature. Surface data obtained from a thrust bearing surface are characterized and used to calculate the fractal dimension value by the roughness-length method. Then these parameters are used to generate different rough surfaces via a filtering algorithm. By comparing the predicted performance between the measured surface and generated fractal surfaces, it is found that the fractal dimension must be used carefully when characterizing the tribological performance of rough surfaces, and other parameters need to be found.

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Mixed Lubrication of Coupled Journal-Thrust-Bearing Systems Including Mass Conserving Cavitation

Journal of Tribology ◽

10.1115/1.1574519 ◽

2003 ◽

Vol 125 (4) ◽

pp. 747-755 ◽

Cited By ~ 17

Author(s):

Yansong Wang ◽

Q. Jane Wang ◽

Chih Lin

Keyword(s):

Conformal Mapping ◽

Boundary Conditions ◽

Thrust Bearing ◽

Mixed Lubrication ◽

Mapping Technique ◽

Computational Domain ◽

Misalignment Angle ◽

Governing Equations ◽

Reynolds Equations ◽

Bearing System

A mixed lubrication model is developed to investigate the lubrication of coupled journal-thrust-bearing systems. The governing equations are mapped into a computational domain with a conformal mapping technique developed in a previous study by Wang et al. (2002). In order to study the influence of the boundary conditions on the performance of the bearing system, either the Reynolds boundary conditions or the JFO’s mass conserving conditions are applied to the governing Reynolds equations. The performance of a typical coupled journal-thrust bearing system is numerically investigated and the effects of viscosity, misalignment angle and feeding scheme are discussed.

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