Gas foil bearings (GFBs) enable efficient, reliable and maintenance free operation of high-power-density microturbomachinery (< 200 kW). High speed rotors supported on bump-type GFBs, however, are prone to show large-amplitude subsynchronous motions albeit reaching limit cycle performance. Presently, commercial GFBs are simply modified to introduce a mechanical preload that induces a hydrodynamic wedge to generate more load support and direct stiffnesses. Three metal shims inserted under the bump strip layers and in contact with the bearing housing create a multiple lobe clearance profile at a very low cost. Shaft speed coastdown measurements reveal the rotordynamic performance of a rotor supported on original GBFs and (modified) shimmed GFBs. The later GFBs determine a raise in the rotor-bearing system natural frequency, as expected, and also act to delay the onset speed of large-amplitude subsynchronous motions. Predictions of imbalance response implementing linearized bearing force coefficients are in good agreement with measured amplitudes of synchronous response for both GFB configurations, original and modified.
- Tribology Division
Effect of Mechanical Preloads on the Dynamic Performance of Gas Foil Bearings
Kim, TH, & San Andre´s, L. "Effect of Mechanical Preloads on the Dynamic Performance of Gas Foil Bearings." Proceedings of the STLE/ASME 2008 International Joint Tribology Conference. STLE/ASME 2008 International Joint Tribology Conference. Miami, Florida, USA. October 20–22, 2008. pp. 379-381. ASME. https://doi.org/10.1115/IJTC2008-71195
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