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Title: Modelling of flow in air-riding bearings with lift generating features
Author: Vosper, Hayley
ISNI:       0000 0004 6349 7384
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2014
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Air-riding thrust bearings are comprised of a solid, annular rotor and stator in relative rotational motion separated by a thin air film, often with a pressure difference across the annulus. Lift-generating features may be in the form of geometric structures added to the surface of the rotor/stator and are designed to enhance the dynamic properties of the fluid film and increase the efficiency of the bearing. This thesis is focussed on modelling the air film in air-riding bearings and the effects of lift-generating features on the dynamic performance. A review of the relevant literature highlighted a lack of current models incorporating fully periodic boundary conditions and a limited understanding of flow near abrupt geometrical features such as steps. A local analysis was undertaken at a geometric step in an axisymmetric bearing, and matched asymptotically to a classical Reynolds equation based flow model. The effects of the step were measured to first order and gave justification to a widely used patching method. The asymptotic analysis was extended to azimuthal step orientations and yielded similar results. The steady Reynolds equation was solved with fully periodic boundary conditions for a range of bearing geometries and both incompressible/compressible flow models. Analytical methods were used where available and a verified finite element method was implemented using Matlab. Extensive results in the form of pressure and streamline plots were presented alongside key bearing quantities for a range of parameters. The motion of flexible lift-generating features in the form of rigid, hinged pads was coupled with a transient flow model and subjected to periodic axial oscillations of the rotor. The dynamic response of the fluid and pads was calculated and displayed for a range of relevant flow quantities. The numerical models in this thesis are also valuable for optimization of bearing geometry and related parameters.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available