Abstract
This paper presents an analysis of galloping-based wind energy harvesters with piezoelectric and electromagnetic transductions. The lumped parameter models of the galloping-based piezoelectric energy harvester (GPEH) and galloping-based electromagnetic energy harvester (GEMEH) are developed and the approximate analytical solutions of the equations are derived using the harmonic balance method (HBM). The accuracy of the approximate analytical solutions is validated by the numerical solutions. A parametric study is then conducted based on the validated models and solutions to understand the effects of the dimensionless load resistance, r, and electromechanical coupling strength (EMCS) on various quantities indicating the performance of the harvesters, including the dimensionless oscillating frequency, cut-in wind speed, displacement, and average power output. The results show that both r and EMCS can affect the dimensionless oscillating frequencies of the GPEH and GEMEH in a narrow frequency range around the natural frequency. A significant decrease in the displacement around r = 1 for GEPH and at a low r for GEMEH indicates the damping effect induced by the increase in EMCS. There are two optimal r to achieve the maximal power output for GPEH given strong EMCS while there is only one optimal r for GEMEH. Both GPEH and GEMEH show similar characteristics in that the optimal power outputs can reach saturation with an increase of the EMCS. The findings from the parametric study provide useful guidelines for the design of galloping-based energy harvesters with different energy conversion mechanisms.
Highlights
In recent years, the field of energy harvesting has received significant research interest due to the quest to exploit renewable energy sources
It is impractical to shrink the size of wind turbines to harvest small wind energy due to higher manufacturing costs and lower energy harvesting efficiency
Parametric studies are performed to investigate the effects of the load resistance and electromechanical coupling strength (EMCS) on the dimensionless oscillating frequency, cut-in wind speed, displacement, and average power output for the galloping-based piezoelectric energy harvester (GPEH) and galloping-based electromagnetic energy harvester (GEMEH) based on the validated models and the approximate analytical solutions
Summary
The field of energy harvesting has received significant research interest due to the quest to exploit renewable energy sources. Many researchers have studied the effect of various geometries of cross-sections of the bluff bodies on energy harvesting performance [13,14,15,16,17,18], where square [14], triangular [15], rectangular [16], and D-section [17] sections are available in the literature. Abdelkefi et al [21] theoretically studied the effect of the cross-section geometry (square, triangle, and D-section) on the onset speed of galloping and the level of the output power. Parametric studies are performed to investigate the effects of the load resistance and EMCS on the dimensionless oscillating frequency, cut-in wind speed, displacement, and average power output for the GPEH and GEMEH based on the validated models and the approximate analytical solutions. The effect of the EMCS on the optimal average power outputs of the GPEH and GEMEH is investigated
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