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Harness Aquatic Clean Energy from Vortex Induced Vibration

Nemati Kourabbasloo, Navid | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48545 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Abbaspour, Madjid; Afshin, Hossein
  7. Abstract:
  8. Transverse Vortex-Induced Vibration(VIV) and Flow-Induced Vibration(FIV) of a rigid, circular, elastically mounted single degree of freedom cylinder is scrutinized in range 3×104≤ Re ≤12×104 by means of Computational Fluid Dynamics(CFD). ANSYS CFX, based on FV, is employed to simulate VIV and FIV in different system parameters such as stiffness and mass ratio. Firstly, the minimum structured, hexahedron computational cell required to simulate VIV and FIV by means of Finite Volume (FV) method is provided. Then, the appropriate size for computational domain to simulate VIV and FIV accurately is discussed concisely. Approximated amplitude and frequency ratio are compared to experimental data reported by Michigan University Marine Renewable Energy Laboratory (MRELab). Phase angle between lift coefficient and amplitude ratio is compared qualitatively to experimental data reported by Cornell University ONR Water Channel. An appropriate 2-dimensional (2D) turbulence model is introduced that is capable to simulate smooth circular cylinder VIV. It has been shown that applying roughness strips expands high-amplitude Reynolds numbers range. Moreover, it is demonstrated that the forgoing model is able to distinguish the occurrence or nonexistence of galloping phenomenon back to back to VIV of a cylinder with surface roughness according to the variation of system parameters. Mass ratio and stiffness effect on amplitude ratio, frequency ratio, harnessed power, and convertor efficiency is investigated. The VIV maximum amplitude and frequenct are achieved at very low mass ratio. Affected by frequency and amplitude ratio map, some new vortex patterns such as 4S (single), T (Triplet), 2C, T+S+S and 2S+C are observed in smooth circular cylinder VIV. The rough circular cylinder FIV maximum amplitude and power is reached at medium mass ratio and belongs to galloping branch
  9. Keywords:
  10. Finite Volume Method ; Vortex-Induced Vibration (VIV) ; Galloping ; ANSYS Software ; Flow Induced Vibration ; Vortex Pattern

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