Modeling and Experimental Characterization of a Piezoelectric Energy Harvester with a Wind Concentrator Structure

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RESEARCH ARTICLE-MECHANICAL ENGINEERING

Modeling and Experimental Characterization of a Piezoelectric Energy Harvester with a Wind Concentrator Structure Jiantao Zhang1

· Pengyu Wang1 · Yiwen Ning1 · Wei Zhao1 · Xiaobo Zhang1

Received: 1 February 2020 / Accepted: 17 September 2020 © King Fahd University of Petroleum & Minerals 2020

Abstract Piezoelectric wind energy harvesters have gained much attention in recent years due to their potential as renewable energy sources for wireless sensor networks. However, the low energy output limits its application in practice. In order to improve the output performance, a piezoelectric wind energy harvester with a wind concentrator structure is studied. The wind concentrator structure is used to concentrate the wind flow and improve the vibration characteristics and output performance of the harvester. An analytical model is developed to describe the interaction between the fluid and the solid. Various analytical results, such as the velocity contour and the pressure contour for the flow, displacement of the free end of the polyvinylidene fluoride (PVDF) beam, are obtained. The influences of the position parameters of the PVDF beam on the vibration displacement are analyzed. The prototype harvester was fabricated and measured experimentally. The trend of simulation results is consistent with that of measured data. When the wind speed is 14 m/s, the output voltage RMS (root mean square) of the harvester with and without the wind concentrator are 2.23 V and 1.16 V, respectively. The output voltage RMS of the former is about two times that of the latter. This experiment verifies the validity of the wind concentrator. Keywords Piezoelectric · Energy harvesting · Analytical model · PVDF beam

List of Symbols

σε

w

Sk , Sε d 31 E s11

l

Gk Gb YM C 1ε , C 2ε , C 3ε σk

B 1

The transverse distance between the free end of the PVDF beam and the wind concentrator outlet The longitudinal distance between the free end of the PVDF beam and the wind concentrator outlet The production of turbulent kinetic energy caused by the average velocity gradient The production of turbulent kinetic energy caused by buoyancy The contribution of compressible turbulence in pulse expansion Empirical constants The corresponding Prandtl number of turbulent kinetic energy

Jiantao Zhang [email protected] School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200072, China

T ε33 Me Ce Ke Z U αe Fg RL Cp

k I V avg C L

The corresponding Prandtl number of dissipation rate The source of user defined The piezoelectric coupling coefficient The flexible constant of piezoelectric material The dielectric constant The equivalent mass of the PVDF beam The equivalent damping of the PVDF beam The equivalent stiffness of the PVDF beam The displacement of the equivalent mass The output voltage The electromechanical coupling coefficient The applied fluid force The load resistance The equivalent capacitance of the PVDF beam Turbulence kinetic energy Turbulence level Mean velocity An empirical