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Other (Seals, Manufacturing)

# Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing

[+] Author and Article Information
Ren Liu

School of Mechanical Engineering,  Beijing Institute of Technology, Beijing, P. R. C. 100081niuren@bit.edu.cn

Xiao-Li Wang

School of Mechanical Engineering,  Beijing Institute of Technology, Beijing, P. R. C. 100081xiaoli_wang@bit.edu.cn

Xiao-Qing Zhang

School of Mechanical Engineering,  Beijing Institute of Technology, Beijing, P. R. C. 100081xiaogear@bit.edu.cn

J. Tribol 134(2), 022201 (Apr 12, 2012) (7 pages) doi:10.1115/1.4006359 History: Received October 06, 2011; Revised March 12, 2012; Published April 11, 2012; Online April 12, 2012

## Abstract

The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

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## Figures

Figure 1

Schematic of spiral groove bearing system (a) spiral groove geometry and (b) spiral groove bearing system

Figure 2

Coordinates transformation of spiral curve

Figure 3

Finite volume discretization in spiral coordinatess. I: finite volume in the ridge area; II: finite volume separated by boundary; III: finite volume in the groove area.

Figure 4

Comparison with the available numerical results of dimensionless load for spiral groove gas thrust bearings

Figure 5

Comparison with the results of Malanoski and Pan [16] and Zirkelbck and Andres [14]. (a) Dimensionless axial stiffness versus frequency number for various compressibility numbers; (b) dimensionless axial damping versus frequency number for various compressibility numbers.

Figure 6

Circumferential pressure distribution at radius is 1.5 mm. (a) Λ=12; (b) Λ=60.

Figure 7

Effects of gas rarefaction on dynamic coefficients with fixed compressibility number: (a) dimensionless stiffness coefficients; (b) dimensionless damping coefficients

Figure 8

Influence of dimensionless gas rarefaction on stiffness with different compressibility number: (a) dimensionless stiffness Kxx, Kyy; (b) dimensionless stiffness Kzz

Figure 9

Comparison of the results between dynamic coefficients considering and without considering micro scale effects: (a) dimensionless stiffness coefficients versus compressibility number; (b) dimensionless damping coefficients versus compressibility number

Figure 10

Influence of dimensionless gas rarefaction on dynamic coefficients with different gas film thickness: (a) dimensionless stiffness; (b) dimensionless damping coefficients

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