Effect of Ellipticity on Cavitation Mechanism and Thermal Effect of Elliptical Journal Bearings

This paper used a new transient computational fluid dynamics and fluid–structure interaction method to investigate the journal bearing performance with the effect of thermal and cavitation, to reveal the performance of journal bearing in different lubricants and to provide substitution references for bearings in different lubricants. Considering thermal effect, elastic deformation and cavitation, a detailed discussion was conducted to show the performance of plain journal bearings lubricated by water, seawater, and lubricating oil by computational fluid dynamics (CFD) and fluid structure interaction (FSI) method. And the results in this work are compared with the published results. The variation of dimensionless load carrying capacity, maximum film pressure and temperature with eccentricity ratio are presented, which can provide reference for the design of bearings. Furthermore, a diagram is presented for journal bearings with different diameter, length-diameter ratio and lubricants, which can be used as a reference for the equivalent substitutions of bearings. The present research provides references as to the design of bearings and the substitutions of bearings by different lubricants.

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Stability Analysis of Grooved Journal Bearings in High-Speed Hard Disk Drive Considering Thermal Effect

2009 International Conference on Measuring Technology and Mechatronics Automation ◽

10.1109/icmtma.2009.481 ◽

2009 ◽

Author(s):

Honglai Li ◽

Shuzhong Lin ◽

Jing Wang ◽

Zhiguo Zheng ◽

Jintai Lin ◽

...

Keyword(s):

Stability Analysis ◽

Thermal Effect ◽

Hard Disk Drive ◽

High Speed ◽

Hard Disk ◽

Disk Drive ◽

Journal Bearings

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Thermohydrodynamic Lubrication Analysis of Misaligned Plain Journal Bearing With Rough Surface

Journal of Tribology ◽

10.1115/1.4000515 ◽

2009 ◽

Vol 132 (1) ◽

Cited By ~ 24

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.

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UHV-STM studies of silicon nano-pyramid growth on silicon surface at high temperature

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130353 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1144-1145

Author(s):

T. Sato ◽

S. Kitamura ◽

T. Sueyoshl ◽

M. Iwatukl ◽

C. Nielsen

Keyword(s):

High Temperature ◽

Relaxation Process ◽

Thermal Effect ◽

Bias Voltage ◽

Silicon Surface ◽

Growth Process ◽

Tunneling Current ◽

Fabrication Technique ◽

Nano Fabrication ◽

Electromigration Effect

Recently, the growth process and relaxation process of crystalline structures were studied by observing a SI nano-pyramid which was built on a Si surface with a UHV-STM. A UHV-STM (JEOL JSTM-4000×V) was used for studying a heated specimen, and the specimen was kept at high temperature during observation. In this study, the nano-fabrication technique utilizing the electromigration effect between the STM tip and the specimen was applied. We observed Si atoms migrated towords the tip on a high temperature Si surface.Clean surfaces of Si(lll)7×7 and Si(001)2×l were prepared In the UHV-STM at a temperature of approximately 600 °C. A Si nano-pyramid was built on the Si surface at a tunneling current of l0nA and a specimen bias voltage of approximately 0V in both polarities. During the formation of the pyramid, Images could not be observed because the tip was stopped on the sample. After the formation was completed, the pyramid Image was observed with the same tip. After Imaging was started again, the relaxation process of the pyramid started due to thermal effect.

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