This paper investigates the energy production of a “meso-scale”, wind-based energy harvester that exploits the torsional aeroelastic instability of a rigid blade-airfoil, elastically supported at equidistant supports. Torsional flutter is a single mode aeroelastic instability phenomenon, in which a diverging dynamic angular rotation of a body occurs. The apparatus relies on a simple mechanism that uses flow-induced pitch motion to extract and convert airflow kinetic energy to electrical energy. The system is composed by a rigid blade-airfoil, connected to a support structure through a non-linear restoring force (torsional spring-like) mechanism that enables the rotation about a reference pivot axis. The proposed technology is designed to be efficient in the range of low and medium wind speeds (10-13 m/s), in which horizontal-axis wind turbines and other harvesters are not efficient. Deterministic pre-flutter, incipient flutter and post-critical vibrations of the apparatus have been already explored in a previous study. This work aims to further investigate the aeroelastic behavior of the “flapping foil” by examining the effect of turbulence, random experimental error and modeling simplifications of the aeroelastic forces. The analysis is conducted at incipient flutter in the frequency domain using classical unsteady force models. Monte Carlo methods are employed to solve for the probability of incipient flutter speed. Several configurations are considered to improve the efficiency of the energy harvester.
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Harvesting Energy From an Ionic Polymer–Metal Composite in a Steady Air Flow
Abstract The paper presents the results of an investigation of a possibility for energy harvesting from a flexible material such as an ionic polymer–metal composite (IPMC) placed in a steady flow of air characteristic of conditions typical to a densely urbanized area. As electro-active devices require dynamic loading to produce current, their response is usually evaluated in unsteady and turbulent flows, where an electro-active polymer follows the movement of the medium surrounding the device. In our study, we examine the flow conditions at which flutter sets the IPMC strip in motion. Although flutter is often perceived as an unfavorable phenomenon for aerodynamic applications and civil structures, it may be beneficial for harvesting wind energy. Of particular interest is that this phenomenon may occur in a steady flow, which potentially expands the range of favorable flow conditions for energy harvesting. In the paper, the air speed at which flutter occurs and the speed range at which flutter is sustained are provided along with the estimated amount of power produced in an IPMC sample of specified dimensions.
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- Award ID(s):
- 1757207
- PAR ID:
- 10156088
- Date Published:
- Journal Name:
- Journal of Fluids Engineering
- Volume:
- 142
- Issue:
- 8
- ISSN:
- 0098-2202
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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