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dc.contributor.advisorTinney, Charles Edmund, 1975-en
dc.creatorMula, Swathi Mahalaxmien
dc.date.accessioned2015-08-03T13:43:46Zen
dc.date.issued2015-05en
dc.date.submittedMay 2015en
dc.identifier.urihttp://hdl.handle.net/2152/30268en
dc.descriptiontexten
dc.description.abstractThe stability and turbulence characteristics of a vortex filament emanating from a single-bladed rotor in hover are investigated using proper orthogonal decomposition. The rotor is operated at a tip chord Reynolds number and a tip Mach number of 218,000 and 0.22, respectively, and with a blade loading of CT /σ = 0.066. In-plane components of the velocity field (normal to the axis of the vortex filament) are captured by way of 2D particle image velocimetry with corrections for vortex wander being performed using the Γ1 method. Using the classical form of POD, the first POD mode alone is found to encompass nearly 75% of the energy for all vortex ages studied and is determined using a grid of sufficient resolution as to avoid numerical integration errors in the decomposition. The findings reveal an equal balance between the axisymmetric and helical modes during vortex roll-up which immediately transitions to helical mode dominance at all other vortex ages. This helical mode is one of the modes of the elliptic instability. While the snapshot POD is shown to reveal similar features of the first few energetic modes, the classical POD is employed here owing to the easier interpretation of the Fourier-azimuthal modes. The spatial eigenfunctions of the first few Fourier-azimuthal modes associated with the most energetic POD mode are shown to be sensitive to the choice of the wander correction technique used. Higher Fourier-azimuthal modes are observed in the outer portions of the vortex and appeared not to be affected by the choice of the wander correction technique used.en
dc.format.mimetypeapplication/pdfen
dc.language.isoenen
dc.subjectInstabilityen
dc.subjectTurbulenceen
dc.subjectTip vortexen
dc.subjectRotoren
dc.subjectVortex wanderen
dc.subjectProper orthogonal decompositionen
dc.subjectParticle image velocimetryen
dc.titleStability and turbulence characteristics of a spiraling vortex filament using proper orthogonal decompositionen
dc.typeThesisen
dc.date.updated2015-08-03T13:43:47Zen
dc.description.departmentAerospace Engineering
thesis.degree.departmentAerospace Engineeringen
thesis.degree.disciplineAerospace Engineeringen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen


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