Air foil bearings offer several advantages over oil-lubricated bearings in high
speed micro-turbomachinery. With no contact between the rotor and bearings, the air foil
bearings have higher service life and consequently lesser standstills between operations.
However, the foil bearings have reliability issues that come from dry rubbing during
start-up/shutdown and limited heat dissipation capability. Regardless of lubricating
media, the hydrodynamic pressure generated provides only load support but no
dissipation of parasitic energy generated by viscous drag and the heat conducted from
other parts of the machine through the rotor.
The present study is a continuation of the work on hybrid air foil bearings
(HAFB) developed by Kim and Park, where they present a new concept of air foil
bearing combining hydrodynamic air foil bearing with hydrostatic lift. Their
experimental studies show that HAFB has superior performance compared to its
hydrodynamic counterpart in load capacity and cooling performance.
In this article, the bearing stiffness and damping coefficients of HAFB are calculated
using a linear perturbation method developed for HAFB. The study focuses on circular
HAFB with a single continuous top foil supported by bump foil. The research also includes a parametric study which outlines the dependence of the stiffness and damping
coefficients on various design parameters like supply pressure ( P s ), feed parameter ( Г s ),
excitation frequency (v), and bearing number (Λ).
Furthermore the present research also includes experimental investigation of
HAFB with bump foil as compliant structure. In the first phase of the experimental
research a high speed test facility was designed and fabricated. The facility has the
capability of running up to 90,000 RPM and has an electric motor drive. This article
gives detailed description of this test rig and also includes data acquired during the
commissioning phase of the test rig. The test rig was then used to measure the load
capacity of HAFB.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3004 |
| Date | 15 May 2009 |
| Creators | Kumar, Manish |
| Contributors | Kim, Daejong |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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