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dc.contributor.advisorKim, Daejongen_US
dc.creatorRimpel, Aaron Michaelen_US
dc.date.accessioned2010-01-15T00:09:21Zen_US
dc.date.accessioned2010-01-16T01:12:06Z
dc.date.available2010-01-15T00:09:21Zen_US
dc.date.available2010-01-16T01:12:06Z
dc.date.created2008-08en_US
dc.date.issued2009-05-15en_US
dc.identifier.urihttp://hdl.handle.net/1969.1/ETD-TAMU-3011
dc.description.abstractHydrodynamic flexure pivot tilting pad gas bearings (FPTPGBs) can enable successful operation of oil-free microturbomachinery. This work presents the experimental and analytical study of such bearings with different damper configurations. A test rig was constructed that could safely operate a ~28.6 mm, 0.8 kg rotor beyond 120 krpm. A time domain orbit simulation, which integrates nonlinear equations of motion for the rotor-bearing elements, was implemented as the primary analysis tool to predict rotor-bearing responses to imbalance, the presence and location of critical speeds, etc. Complementary analyses were also performed with a model that uses linear bearing impedance coefficients to predict system natural frequencies. Imbalance response testing verified that the rotor-bearing system behaved linearly in the region above the critical speed, and orbit simulations predicted the response to a calibrated imbalance with notable agreement. Viscoelastic dampers added behind the FPTPGB pads delayed the onset of subsynchronous vibrations (from 43 krpm without damper to above 50 krpm with damper) of the system with bearing clearance increased by shims. Midrange subsynchronous vibrations initiated at ~20 krpm were eventually suppressed by ~25 krpm due to the stabilizing effect of rotor centrifugal growth. The viscoelastic dampers had a negligible effect on suppressing these midrange subsynchronous vibrations in experiments, but this was not demonstrated in simulations, presumably due to much lower stiffness contribution of the damper at lower frequencies. The ideal, perfectly aligned models in the simulations were able to tolerate shims up to only 10% of nominal clearance, but the test rig exhibited surprising stability with shims as much as 200% of nominal clearance; this increase may be caused by imposed eccentricities due to misalignments in the test rig. FPTPGBs supported by compliant bump foils can have the ability to tolerate rotor misalignments and shock loading like foil gas bearings. Simulation studies on imbalance response characteristics for several bearing shell mass and support stiffness configurations present initial design guidelines for the application. Namely, results showed that FPTPGBs favored large bearing shell mass and large support stiffness, while FPTPGBs with radial compliance favored small bearing shell mass with large support stiffness.en_US
dc.format.mediumelectronicen_US
dc.format.mimetypeapplication/pdfen_US
dc.language.isoen_USen_US
dc.subjectTilting pad gas bearingsen_US
dc.titleAnalysis of flexure pivot tilting pad gas bearings with different damper configurationsen_US
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentMechanical Engineeringen_US
thesis.degree.disciplineMechanical Engineeringen_US
thesis.degree.grantorTexas A&M Universityen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelMastersen_US
dc.contributor.committeeMemberJeong, Hae-Kwonen_US
dc.contributor.committeeMemberPalazzolo, Alan B.en_US
dc.type.genreElectronic Thesisen_US
dc.type.materialtexten_US
dc.format.digitalOriginborn digitalen_US


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