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Harvesting of Aquatic Clean Energy from Vortex Induced Vibration Using Two Degree Of Freedom Cylindrical Oscillator and Piezoelectric

Hassani Fakhrabadi, Pouria | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53534 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Raie, Mohammad
  7. Abstract:
  8. Vortex-induced vibration is a known phenomenon in fluids flow that is being studied in different fields of engineering and usually, we want to reduce the harmful effects of this phenomenon on the subjected structures. Also, it is possible to use this phenomenon for harvesting clean energy from fluids flow. Energy harvesting from vortex-induced vibrations is based on the maximizing of flow instead of its reduction, and the utilization of these vibrations instead of their suppression. Vortex induced vibrations occur in any ranges of Reynolds numbers. Only in three transient regions cause a reduction in vortex-induced vibrations; therefore, even in streams with a velocity less than 0.2 m/s, it is possible to harvest energy from vortex-induced vibrations as a source of renewable energy with a high transformation ratio. There are different methods to utilize this mechanical power and convert it to electrical power like electromagnetic induction, electrostatic turbines, and piezoelectric. Making changes in different characteristics of the test like the oscillator’s mass and geometry can make changes in the oscillation amplitude, vibration type, and the harnessed power as a result. Most of the previous studies were about the single degree of freedom oscillator. This study tried to generate a single degree of freedom and two degrees of freedom movements and harvesting power from them by using piezoelectric in laboratory tests then the efficiency of the two degrees of freedom tests compared with the single degree of freedom ones. Test results show that there is an increase in harvested power from the two degrees of freedom vibrations in comparison to the single degree of freedom vibrations’ power. Tests are done in the Reynolds number range from 3817 to 5037. Test results show that the electrical harvested power efficiency ratio to the fluid flow for the two degrees of freedom oscillation is up to 10 times greater than the single degree of freedom oscillator. Also, in the two degrees of freedom oscillation with piezoelectric, the vertical and horizontal amplitudes to the oscillator diameter ratios are 0.40 and 0.15 respectively while for the oscillation with one degree of freedom and piezoelectric the amount of vertical oscillation amplitude to the oscillator diameter ratio is 0.26. Therefore, the amount of vertical amplitude in the two degree of freedom oscillation with piezoelectric is up to 1.5 times is greater than the one degree of freedom with piezoelectric oscillation’s vertical amplitude
  9. Keywords:
  10. Vortex Interaction ; Strouhal Number ; Piezoelectric ; Vortex-Induced Vibration (VIV) ; Cylindrical Oscillator ; Two Degrees of Freedom Oscillator ; Clean Aquatic Energy Harvesting

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