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Confinement Effects on the Hydrodynamic Performance of a Fully-Passive Oscillating-Foil Turbine

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dc.contributor.author Mann, Sierra
dc.date.accessioned 2022-08-05T18:58:30Z
dc.date.available 2022-08-05T18:58:30Z
dc.date.copyright 2022 en_US
dc.date.issued 2022-08-05
dc.identifier.uri http://hdl.handle.net/1828/14086
dc.description.abstract Current emissions targets have created a strong need for introducing more renewable energy sources into the energy mixture. The oscillating-foil turbine (OFT) has gained interest in recent years for renewable energy extraction. Experimental and numerical studies on the OFT experience different levels of wall confinement than what may be experienced at a natural site. Walls in close proximity will direct the flow at the turbine, causing a greater perceived velocity by the turbine, and thus a higher theoretical performance. This work aims to increase understanding of flow confinement on the fully-passive OFT. This is motivated by (1) enabling comparison between turbine performance operating at different confinement levels, and (2) potentially providing a means to enhance performance by designing a turbine which uses confinement to its advantage. The experiments were performed using a NACA0015 foil with an aspect ratio of 7.5 in a water tunnel equipped with adjustable lateral walls. The foil was undergoing passive oscillations in pitch and heave degrees of freedom. The kinematic parameters of the foil oscillations and its energy harvesting performance were measured at eight blockage ratios, ranging from 22% to 60%, for two structural configurations of the turbine. Quantitative flow imaging was performed using particle image velocimetry (PIV), at three confinement levels, to observe the timing of the leading-edge vortex (LEV) formation and shedding throughout the foil oscillation cycle. Loading on the foil was related to the flow structure by calculating the moments of vorticity with respect to the pitching axis of the foil. The results showed that the efficiency and the power coefficient increased with increasing confinement. This was expected due to the higher incident velocity on the foil in the presence of the confining walls. At the highest level of confinement, the close proximity of the foil to the walls during parts of the oscillation cycle resulted in a change in the phase lag between the pitching and the heaving components of the foil motion. In turn, this shift in the kinematic parameters led to a sharp decrease in the energy-extraction performance of the turbine. en_US
dc.language English eng
dc.language.iso en en_US
dc.rights Available to the World Wide Web en_US
dc.subject energy en_US
dc.subject turbine en_US
dc.subject confinement en_US
dc.subject fluid structure interaction en_US
dc.title Confinement Effects on the Hydrodynamic Performance of a Fully-Passive Oscillating-Foil Turbine en_US
dc.type Thesis en_US
dc.contributor.supervisor Oshkai, Peter
dc.contributor.supervisor Dumas, Guy
dc.degree.department Department of Mechanical Engineering en_US
dc.degree.level Master of Applied Science M.A.Sc. en_US
dc.description.scholarlevel Graduate en_US


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