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dc.contributor.authorChiu, Ya-Tienen_US
dc.date.accessioned2014-03-14T20:44:15Z
dc.date.available2014-03-14T20:44:15Z
dc.date.issued1999-07-21en_US
dc.identifier.otheretd-082599-160155en_US
dc.identifier.urihttp://hdl.handle.net/10919/34775
dc.description.abstractHydraulic energy absorbers may be described as high-loss centrifugal turbomachines arranged to operate as stalled torque converters. The device absorbs the kinetic energy of a vehicle in motion and dissipates the energy into water. A steady, single-phase, Computational Fluid Dynamics (CFD) simulation has been performed to investigate the flow field in a hydraulic energy absorber. It was determined that to better predict the performance of the energy absorber, more sophisticated modeling approaches may be needed. In this research, a steady, two-phase calculation with basic turbulence modeling was used as a first assessment. The two-phase model was used to investigate cavitation effects. Unsteady and advanced turbulence modeling techniques were then incorporated into single-phase calculations. The Multiple Reference Frame (MRF) Technique was used to model the interaction between the rotor and the stator. The calculations provided clearer details of the flow field without dramatically increasing the computational cost. It was found that unsteady modeling was necessary to correctly capture the close coupling between the rotor and the stator. The predicted torque in the unsteady calculations was 70% of the experimental value and twice of the result in the steady-state calculations. It was found that the inaccuracy of torque prediction was due to (1) high pressures in the regions with complicated geometrical boundaries and, (2) dynamic interactions between the rotor and the stator were not captured fully. It was also determined that the unrealistically low pressure values were not caused by the physical cavitation, but by the lack of proper boundary conditions for the model. Further integration of the modeling techniques studied would improve the CFD results for use in the design of the energy absorber.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartETD_Main.pdfen_US
dc.relation.haspartAppendix_E.pdfen_US
dc.relation.haspartAppendix_D.pdfen_US
dc.relation.haspartVita.pdfen_US
dc.relation.haspartAppendix_C.pdfen_US
dc.rightsI hereby grant to Virginia Tech or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation.en_US
dc.subjectEnergy Absorberen_US
dc.subjectCFDen_US
dc.subjectHydraulicen_US
dc.subjectComputational Fluid Dynamicsen_US
dc.titleComputational Fluid Dynamics Simulations of Hydraulic Energy Absorberen_US
dc.typeThesisen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMechanical Engineeringen_US
dc.contributor.committeechairKing, Peter S.en_US
dc.contributor.committeememberO'Brien, Walter F. Jr.en_US
dc.contributor.committeememberDancey, Clinton L.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-082599-160155/en_US
dc.date.sdate1999-08-25en_US
dc.date.rdate2000-08-31
dc.date.adate1999-08-31en_US


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