Effect of Mechanical Preloads on the Dynamic Performance of Gas Foil Bearings Conference Paper uri icon

abstract

  • Gas foil bearings (GFBs) enable efficient, reliable and maintenance free operation of high-power-density microturbomachinety (< 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. Copyright © 2008 by ASME.

author list (cited authors)

  • Kim, T. H., Andres, L. S., & ASME, ..

publication date

  • October 2009