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A contribution to the thermal modeling of bump type air foil bearings: Analysis of the thermal resistance of bump foils.

Lehn, Andreas and Mahner, Marcel and Schweizer, Bernhard (2017):
A contribution to the thermal modeling of bump type air foil bearings: Analysis of the thermal resistance of bump foils.
In: Journal of Tribology Transactions of the ASME, pp. 061702-061702, 139, (6), ISSN 1528-8897, DOI: 10.1115/1.4036631, [Article]

Abstract

A detailed analysis of the effective thermal resistance for the bump foil of air foil bearings (AFBs) is performed. The presented model puts emphasis on the thermal contact resistances between the bump foil and the top foil as well as between the bump foil and the base plate. It is demonstrated that most of the dissipated heat in the lubricating air film of an air foil bearing is not conducted by microcontacts in the contact regions. Instead, the air gaps close to the contact area are found to be thin enough in order to effectively conduct the heat from the top foil into the bump foil. On the basis of these findings, an analytical formula is developed for the effective thermal resistance of a half bump arc. The formula accounts for the geometry of the bump foil as well as for the surface roughness of the top foil, the bump foil, and the base plate. The predictions of the presented model are shown to be in good agreement with measurements from the literature. In particular, the model predicts the effective thermal resistance to be almost independent of the applied pressure. This is a major characteristic property that has been found by measurements but could not be reproduced by previously published models. The presented formula contributes to an accurate thermohydrodynamic (THD) modeling of AFBs.

Item Type: Article
Erschienen: 2017
Creators: Lehn, Andreas and Mahner, Marcel and Schweizer, Bernhard
Title: A contribution to the thermal modeling of bump type air foil bearings: Analysis of the thermal resistance of bump foils.
Language: English
Abstract:

A detailed analysis of the effective thermal resistance for the bump foil of air foil bearings (AFBs) is performed. The presented model puts emphasis on the thermal contact resistances between the bump foil and the top foil as well as between the bump foil and the base plate. It is demonstrated that most of the dissipated heat in the lubricating air film of an air foil bearing is not conducted by microcontacts in the contact regions. Instead, the air gaps close to the contact area are found to be thin enough in order to effectively conduct the heat from the top foil into the bump foil. On the basis of these findings, an analytical formula is developed for the effective thermal resistance of a half bump arc. The formula accounts for the geometry of the bump foil as well as for the surface roughness of the top foil, the bump foil, and the base plate. The predictions of the presented model are shown to be in good agreement with measurements from the literature. In particular, the model predicts the effective thermal resistance to be almost independent of the applied pressure. This is a major characteristic property that has been found by measurements but could not be reproduced by previously published models. The presented formula contributes to an accurate thermohydrodynamic (THD) modeling of AFBs.

Journal or Publication Title: Journal of Tribology Transactions of the ASME
Volume: 139
Number: 6
Uncontrolled Keywords: air foil bearing, thermal contact resistance, bump foil, journal and thrust bearings
Divisions: 16 Department of Mechanical Engineering > Institute of Applied Dynamics (AD)
16 Department of Mechanical Engineering
Date Deposited: 08 Nov 2017 15:05
DOI: 10.1115/1.4036631
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