Mixed-lubrication analysis of misaligned journal bearing considering turbulence and cavitation

Purpose The journal bearings subjected to heavy load and slow speed operate in mixed lubrication regime causing contact between the interacting surfaces and resulting in wear. Complexity of wear behavior and lack of unifying theory/model make wear-control very challenging. Design/methodology/approach In the present research work, theoretical and experimental investigations have been conducted to explore the effect of grooving arrangements on the wear behavior of journal bearing operating in mixed lubrication regime. The theoretical model of Hirani (2005) that uses mass conserving cavitation algorithm has been used to determine the bearing eccentricity for different groove arrangements (with varying groove location and extent) for identifying a groove arrangement that minimizes the wear. The wear tests on the grooved bearings were conducted after suitable running-in of the new bearings on a fully automated journal bearing test set-up. A load and speed combination required to operate the bearing in mixed lubrication was used. The performance of different arrangement of bearing was evaluated by measuring their weight loss after the test. Findings Wear was significantly reduced with the use of proper groove arrangement for a bearing operating in mixed lubrication regime. Originality/value The improvement in bearing performance by providing grooves has been the subject matter of several studies in the past, but these studies were confined to the hydrodynamic operative regime of the bearing. In the present work, seven different combinations of axial and radial groove arrangement were tried, which has not been reported in any other work.

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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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Coupling transient mixed lubrication and wear for journal bearing modeling

Tribology International ◽

10.1016/j.triboint.2019.05.011 ◽

2019 ◽

Vol 138 ◽

pp. 1-15 ◽

Cited By ~ 9

Author(s):

Guo Xiang ◽

Yanfeng Han ◽

Jiaxu Wang ◽

Jiefu Wang ◽

Xiaokang Ni

Keyword(s):

Journal Bearing ◽

Mixed Lubrication

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A Mixed-TEHD Model for Journal-Bearing Conformal Contact—Part II: Contact, Film Thickness, and Performance Analyses

Journal of Tribology ◽

10.1115/1.2834411 ◽

1998 ◽

Vol 120 (2) ◽

pp. 206-213 ◽

Cited By ~ 39

Author(s):

Qian (Jane) Wang ◽

Fanghui Shi ◽

Si C. Lee

Keyword(s):

Journal Bearing ◽

Thermal Conditions ◽

Journal Bearings ◽

Mixed Lubrication ◽

Operating Conditions ◽

Contact Theory ◽

Asperity Contact ◽

High Eccentricity ◽

And Performance ◽

Contact Part

Investigation of the mixed lubrication of journal-bearing conformal contacts is very important for failure prevention and design improvement. This paper studies the asperity contact in heavily loaded journal bearings with Lee and Ren’s asperity contact theory in a newly developed mixed-TEHD (Thermal Elasto-Hydro-Dynamic) model and analyzes the performance of simulated journal bearings under high eccentricity ratios. The effects of operating conditions, bearing structures, and thermal conditions on the contact severity were numerically investigated. The results indicate that the asperity contact pressure and the performance of journal bearings in the mixed lubrication are strongly affected by the geometric design and the thermal-elastic deformations. The heat transfer of the bearing-lubricant-journal system was also shown to play a role.

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EFFECT OF THE MISALIGNMENT OF JOURNAL AND SLEEVE AXIS ON THE OPERATION OF TURBO UNIT JOURNAL BEARINGS

Tribologia ◽

10.5604/01.3001.0014.6961 ◽

2021 ◽

Vol 293 (5) ◽

pp. 73-84

Author(s):

Stanisław Strzelecki

Keyword(s):

Power Loss ◽

Journal Bearing ◽

Journal Bearings ◽

Mixed Lubrication ◽

Experimental Results ◽

Rotating Machines ◽

Correct Operation ◽

The Real ◽

Precise Control ◽

Lubrication Conditions

In journal bearings the misalignment of the journal and sleeve axis causes a load concentration on their edges, mixed lubrication conditions, an increase in the bearing temperature, rotor instability, and intensive wear of mating parts. The rotating machines are controlled by means of the temperature and vibration transducers, which are placed in the middle plain of the bearing housing. This arrangement of transducers gives no information about the real distance between the journal surface and bearing edges, and, in case of misaligned shaft, it has crucial meaning for the correct operation of turbo unit. This paper presents the theoretical and some experimental results of turbo unit journal bearing operating in misaligned conditions. The results point out the necessity of the precise control of the lubricating gap and the temperature generated on the bearing edges. It was also found that the increase in misalignment also generates an increase in power loss.

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A Locally Refined Finite Element Approach for Journal-Bearing System Analysis

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-64351 ◽

2005 ◽

Author(s):

S. W. Xiong ◽

Q. Jane Wang ◽

W. K. Liu ◽

Chih Lin ◽

D. Zhu ◽

...

Keyword(s):

System Analysis ◽

Journal Bearing ◽

Numerical Technique ◽

Point Contact ◽

Contact Problems ◽

Journal Bearings ◽

Mixed Lubrication ◽

Special Technique ◽

Simulation Techniques ◽

Refined Meshes

The effect of roughness should be taken into consideration in the lubrication and geometric design of heavy-duty machine elements. Deterministic simulation techniques have been developed for the investigation of point-contact mixed-lubrication problems. Such approaches should also been extended to deterministic mixed lubrication solutions for journal-bearing conformal-contact systems. However, journal-bearing mixed lubrication involves a much larger area of surface interaction as compared to point contact problems. It is difficult to use similar micro/nano scale meshes directly to journal bearings under the current computer capability. It is a great challenge to develop a new deterministic numerical technique for the mixed lubrication of journal bearing systems with the consideration of the effect of surface roughness design. This paper presents a special technique for deterministic analyses of journal-bearings in mixed lubrication conditions, in which the coarse mesh is used to determine the elastic deformation of the journal bearing, whilst locally refined meshes are used for the effect of roughness. Journal-bearing systems in heavy machinery are often subject to dynamic loading. Therefore, a transient refinement scheme is also introduced.

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Profile Design for Misaligned Journal Bearings Subjected to Transient Mixed Lubrication

Journal of Tribology ◽

10.1115/1.4043506 ◽

2019 ◽

Vol 141 (7) ◽

Cited By ~ 1

Author(s):

Thomas Gu ◽

Q. Jane Wang ◽

Shangwu Xiong ◽

Zhong Liu ◽

Arup Gangopadhyay ◽

...

Keyword(s):

Film Thickness ◽

Performance Metrics ◽

Journal Bearing ◽

Hydrodynamic Lubrication ◽

Hydrodynamic Pressure ◽

Industrial Applications ◽

Mixed Lubrication ◽

Asperity Contact ◽

Minimum Film Thickness ◽

Profile Design

Misalignment between the shaft and the bearing of a journal bearing set may be inevitable and can negatively impact journal bearing performance metrics in many industrial applications. This work proposes a convex profile design of the journal surface to help counteract the negative effects caused by such a misalignment. A transient mass-conserving hydrodynamic Reynolds equation model with the Patir–Cheng flow factors and the Greenwood–Tripp pressure–gap relationship is developed to conduct the design and analysis. The results reveal that under transient impulse loading, a properly designed journal profile can help enhance the minimum film thickness, reduce mean and peak bearing frictions, and increase bearing durability by reducing the asperity-related wear load. The mechanism for the minimum film thickness improvement due to the profile design is traced to the more even distribution of the hydrodynamic pressure toward the axial center of the bearing. The reason for the reductions of the friction and wear load is identified to be the decreased asperity contact by changing the lubrication regime from mixed lubrication to nearly hydrodynamic lubrication. Parametric studies and a case study are reported to highlight the key points of the profile design and recommendations for profile height selection are made according to misalignment parameters.

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