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Research Papers: Hydrodynamic Lubrication

Hydrodynamic Behaviors of the Gas-Lubricated Film in Wedge-Shaped Microchannel

[+] Author and Article Information
Xueqing Zhang

Key Laboratory of Low-Grade Energy
Utilization Technologists and Systems
of Ministry of Education,
College of Power Engineering,
Chongqing University,
Chongqing 40030, China
e-mail: xueqingzhang@cqu.edu.cn

Qinghua Chen

Mem. ASME
Key Laboratory of Low-Grade Energy
Utilization Technologists and Systems
of Ministry of Education,
College of Power Engineering,
Chongqing University,
Chongqing 40030, China
e-mail: qhchen@cqu.edu.cn

Juanfang Liu

Key Laboratory of Low-Grade Energy
Utilization Technologists and Systems of
Ministry of Education,
College of Power Engineering,
Chongqing University,
Chongqing 40030, China
e-mail: juanfang@cqu.edu.cn

1Corresponding author.

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received July 1, 2015; final manuscript received October 22, 2015; published online February 15, 2016. Assoc. Editor: Min Zou.

J. Tribol 138(3), 031701 (Feb 15, 2016) (10 pages) Paper No: TRIB-15-1233; doi: 10.1115/1.4031992 History: Received July 01, 2015; Revised October 22, 2015

As for the micro gas bearing operating at a high temperature and speed, one wedge-shaped microchannel is established, and the hydrodynamic properties of the wedge-shaped gas film are comprehensively investigated. The Reynolds equation, modified Reynolds equation, energy equation, and Navier–Stokes equations are employed to describe and analyze the hydrodynamics of the gas film. Furthermore, the comparisons among the hydrodynamic properties predicted by various models were performed for the different wedge factors and the different wall temperatures. The results show that coupling the simplified energy equation with the Reynolds or modified Reynolds equations has an obvious effect on the change of the friction force acting on the horizontal plate and the load capacity of the gas film at the higher wedge factor and the lower wall temperature. The velocity slip weakens the squeeze of the gas film and strengths the gas backflow. A larger wedge factor or a higher wall temperature leads to a higher gas film temperature and thus enhances the rarefaction effect. As the wall temperature is elevated, the load capacity obtained by the Reynolds equation increases, while the results by the Navier–Stokes equations coupled with the full energy equation rapidly decrease. Additionally, the vertical flow across the gas film in the Navier–Stokes equations weakens the squeeze between the gas film and the tilt plate and the gas backflow.

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References

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Figures

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Fig. 1

Schematic of the simplified lubrication film

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Fig. 2

Relative tolerance of each model

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Fig. 3

Dimensionless horizontal velocity along the inlet cross section for the different wedge factors: (a) hf = 1, (b) hf = 5, and (c) hf = 9

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Fig. 4

Dimensionless gas film temperature along the inlet cross section for the different wedge factors: (a) hf = 1, (b) hf = 5, and (c) hf = 9

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Fig. 5

Dimensionless gas film pressure distributions for the different wedge factors: (a) hf = 1, (b) hf = 5, and (c) hf = 9

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Fig. 6

Change of the dimensionless friction force with the wedge factor

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Fig. 7

Change of the dimensionless load capacity with the wedge factor

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Fig. 8

Dimensionless horizontal velocity along the inlet cross section at the different wall temperatures: (a) Twall = 300 K, (b) Twall = 1100 K, and (c) Twall = 1700 K

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Fig. 9

Dimensionless gas film temperature along the inlet cross section at the different wall temperatures: (a) Twall = 300 K, (b) Twall = 1100 K, and (c) Twall = 1700 K

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Fig. 10

Dimensionless gas film pressure distributions at the different wall temperatures: (a) Twall = 300 K, (b) Twall = 1100 K, and (c) Twall = 1700 K

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Fig. 11

Change of the dimensionless friction force with the wall temperature

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Fig. 12

Change of the dimensionless load capacity with the wall temperature

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