Abstract
Aeroelastic energy harvesters are a promising technology for powering wireless sensors and microelectromechanical systems. In this letter, we present a harvester inspired by the trembling of aspen leaves in barely noticeable winds. The galloping energy harvester, a curved blade oriented perpendicular to the flow, is capable of producing self-sustained oscillations at uncharacteristically low wind speeds. The dynamics of the harvesting system are studied experimentally and compared to a lumped parameter model. Numerical simulations quantitatively describe the experimentally observed dynamic behaviour. Flow visualisation is performed to investigate the patterns generated by the device. Dissimilar to many other galloping harvester designs, the flow is found to be attached at the rear surface of the blade when the blade is close to its zero displacement position, hence acting more closely to aerofoils rather than to conventionally used bluff bodies. Simulations of the device combined with a piezoelectric harvesting mechanism predict higher power output than that of a device with the square prism.
Highlights
The nature of the flow field around the tip geometry of a galloping energy harvester fundamentally determines the potential efficiency of the device
We present a harvester inspired by the trembling of aspen leaves in barely noticeable winds
Investigating the influence of different tip cross-section geometries on the performance of galloping energy harvesters has been the subject of several studies with focus being placed on the square, isosceles triangular, and the D shaped cross sections
Summary
The nature of the flow field around the tip geometry of a galloping energy harvester fundamentally determines the potential efficiency of the device. The galloping energy harvester, a curved blade oriented perpendicular to the flow, is capable of producing self-sustained oscillations at uncharacteristically low wind speeds. Investigating the influence of different tip cross-section geometries on the performance of galloping energy harvesters has been the subject of several studies with focus being placed on the square, isosceles triangular, and the D shaped cross sections.16–19 Mathematical approaches have been formulated with both lumped parameter and coupled non-linear distributed models,10,17 while experimental comparisons have been performed with flow conditions controlled inside a wind tunnel.16
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