<p>Due to the exhausting of fossil energy sources and the urgency of environmental-friendly energy, fluid energy as a ubiquitous energy source have been proposed and developed in various applications such as wind energy, ocean energy, solar energy and osmotic energy. The technique of harvesting fluid energy in large scale such as solar energy or wind energy has been developed very, however, small-scale fluid energy harvesting for powering small electronic devices such as wireless sensor networks, actuators and health monitoring devices has received only limited attention. The interdisciplinary research topic of energy harvesting from fluid energy in small scale has drawn gradually more attention for its academic attractiveness and potential engineering applications. Therefore, the focus of present work is on performing experimental study to assess the energy conversion techniques for small wind energy harvesting based on the flow-induced vibrations. In this study, the design of a piezoelectric based device that uses interference bluff body to harvest wind energy at different wind speeds is presented. Forty different prototypes including 8 cantilever beams and 5 cylinders as bluff bodies are fabricated and tested first without interference bluff body in a wind tunnel for the performance evaluation. Then, different interference bluff bodies are used and parametric experimental tests are conducted to investigate the effects of interference bluff body’s properties such as the size and distance from fix oscillating body on the performance of four beam-cylinder configurations as VIV energy harvester. To compare the frequency of oscillating beam and its natural frequency, a numerical simulation based on Finite Element Method is performed to obtain the natural frequency of cantilever beam. It was found that the energy harvester can be greatly improved by placing a fix bluff body as interference bluff body in upstream of the oscillating bluff body. As interference body, a cylinder with three different diameters were chosen and placed at various distances from oscillating cylinder. Through experimental performance, this study reveals that both the appropriate diameter of interference cylinder and the distance between oscillating and interference bluff bodies play a key role in the energy harvester’s performance enhancement. Two different modes of oscillation were observed, depending on type of interference cylinder and its distance from bluff body. The results revealed that placing an interference cylinder with smaller diameter than that of oscillating cylinder significantly enhanced the output voltage of piezoelectric sensor. For all case, the Fast Fourier Transform (FFT) analysis was used to monitor the frequency of oscillating body and these values were compared with the natural frequencies obtained by Finite Element Method’s analysis. The results showed that the shorter beams oscillates with a frequency of about 5 Hz, close to the natural frequency of 6Hz, while the longer beams oscillates with frequency of about 2.2 Hz, close to the natural frequency of 2.17Hz.</p>

A Parametric Study of Piezoelectric Energy Harvesting by Vortex Induced Vibration of a Pair of Cylinders

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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