rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Rotordynamic performance of a rotor supported on bump-type foil bearings: experiments and predictions
  name:
    name part: Rubio Tabares, Dario
    name part: 1980-
    role:
      role term: creator
  name:
    name part: San Andres, Luis A.
    role:
      role term: thesis advisor.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2006
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: electronic
    form: remote
  abstract: Gas foil bearings (GFB) appear to satisfy most requirements for oil-free turbomachinery, i.e. relatively simple in construction, ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal amounts of damping. A test rig for the rotordynamic evaluation of gas foil bearings was constructed. A DC router motor, 25 krpm max speed, drives a 1.02 kg hollow rotor supported on two bump-type foil gas bearings (L = D = 38.10 mm). Measurements of the test rotor dynamic response were conducted for increasing mass imbalance conditions. Typical waterfalls of rotor coast down response from 25 krpm to rest evidence the onset and disappearance of severe subsynchronous motions with whirl frequencies at ~50% of rotor speed, roughly coinciding with the (rigid mode) natural frequencies of the rotor-bearing system. The amplitudes of motion, synchronous and subsynchronous, increase (non) linearly with respect to the imbalance displacements. The rotor motions are rather large; yet, the foil bearings, by virtue of their inherent flexibility, prevented the catastrophic failure of the test rotor. Tests at the top shaft speed, 25 krpm, did not excite subsynchronous motions. In the experiments, the subsynchronous motion speed range is well confined to shaft speeds ranging from 22 krpm to 12 krpm. The experimental results show the severity of subsynchronous motions is related to the amount of imbalance in the rotor. Surprisingly enough, external air pressurization on one side of the foil bearings acted to reduce the amplitudes of motion while the rotor crossed its critical speeds. An air-film hovering effect may have enhanced the sliding of the bumps thus increasing the bearings' damping action. The tests also demonstrate that increasing the gas feed pressure ameliorates the amplitudes of subsynchronous motions due to the axial flow retarding the circumferential flow velocity development. A finite element rotordynamic analysis models the te…
  note: by Dario Rubio Tabares.
  note: "Major Subject: Mechanical Engineering"
  note: Title from author supplied metadata (automated record created on Sep. 15, 2006.)
  note: Vita.
  note: Abstract.
  note: Electronic resource.
  note: Mode of access: World Wide Web.
  note: System requirements: World Wide Web access and Adobe Acrobat Reader.
  note: M. S. Texas A&M University 2006.
  note: Includes bibliographical references.
  note: Text (Thesis).
  subject:
    topic: Major mechanical engineering
  subject:
    topic: structural stiffness
  subject:
    topic: subsynchronous vibrations
  subject:
    topic: Foil Bearings
  identifier: http://hdl.handle.net/1969.1/3854
  record info:
    record content source: TXA
    record creation date: 070131
    record change date: 20151104134107.0
    record identifier: in00002201008