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Investigations of Slip Effect on the Performance of Micro Gas Bearings and Stability of Micro Rotor-Bearing Systems

View Article: PubMed Central

ABSTRACT

Incorporating the velocity slip effect of the gas flow at the solid boundary, the performance and dynamic response of a micro gas-bearing-rotor system are investigated in this paper. For the characteristic length scale of the micro gas bearing, the gas flow in the bearing resides in the slip regime rather than in the continuum regime. The modified Reynolds equations of different slip models are presented. Gas pressure distribution and load carrying capacity are obtained by solving the Reynolds equations with finite different method (FDM). Comparing results from different models, it is found that the second order slip model agrees reasonably well with the benchmarked solutions obtained from the linearized Boltzmann equation. Therefore, dynamic coefficients derived from the second order slip model are employed to evaluate the linear dynamic stability and vibration characteristics of the system. Compared with the continuum flow model, the slip effect reduces dynamic coefficients of the micro gas bearing, and the threshold speed for stable operation is consequently raised. Also, dynamic analysis shows that the system responses change with variation of the operating parameters including the eccentricity ratio, the rotational speed, and the unbalance ratio.

No MeSH data available.


The force component of the micro gas bearing.
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f3-sensors-07-01399: The force component of the micro gas bearing.

Mentions: Solving the Reynolds equations with finite difference method, the gas pressure of the gas film is obtained. Integrating the dimensionless pressure on the surface of the journal, the dimensionless bearing force components along the radial direction Fr and tangential direction Ft as shown in Fig.3 could thus be obtained(18){Fr=∫∫Pcosθ⋅rdθdξFt=∫∫Psinθ⋅rdθdξ


Investigations of Slip Effect on the Performance of Micro Gas Bearings and Stability of Micro Rotor-Bearing Systems
The force component of the micro gas bearing.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814859&req=5

f3-sensors-07-01399: The force component of the micro gas bearing.
Mentions: Solving the Reynolds equations with finite difference method, the gas pressure of the gas film is obtained. Integrating the dimensionless pressure on the surface of the journal, the dimensionless bearing force components along the radial direction Fr and tangential direction Ft as shown in Fig.3 could thus be obtained(18){Fr=∫∫Pcosθ⋅rdθdξFt=∫∫Psinθ⋅rdθdξ

View Article: PubMed Central

ABSTRACT

Incorporating the velocity slip effect of the gas flow at the solid boundary, the performance and dynamic response of a micro gas-bearing-rotor system are investigated in this paper. For the characteristic length scale of the micro gas bearing, the gas flow in the bearing resides in the slip regime rather than in the continuum regime. The modified Reynolds equations of different slip models are presented. Gas pressure distribution and load carrying capacity are obtained by solving the Reynolds equations with finite different method (FDM). Comparing results from different models, it is found that the second order slip model agrees reasonably well with the benchmarked solutions obtained from the linearized Boltzmann equation. Therefore, dynamic coefficients derived from the second order slip model are employed to evaluate the linear dynamic stability and vibration characteristics of the system. Compared with the continuum flow model, the slip effect reduces dynamic coefficients of the micro gas bearing, and the threshold speed for stable operation is consequently raised. Also, dynamic analysis shows that the system responses change with variation of the operating parameters including the eccentricity ratio, the rotational speed, and the unbalance ratio.

No MeSH data available.