Small scale flow energy harvesters are designed to operate at low elevations where surface effects cause significant flow velocity variations. To harness flow energy efficiently in such environments, the harvester must be very sensitive to flow fluctuations. In particular, the rise time of the harvester to the steady-state value must be short. This Letter proposes a method to reduce the rise time of galloping flow energy harvesters by passively manipulating the flow near the trailing edge. To this end, the rear face of the square prism typically used in galloping energy harvesting is augmented with Y-shaped fins of different lengths and fork angles. The addition of the fins is shown to significantly increase the rate at which the magnitude of the normal force coefficient grows with the angle of attack. This, in turn, can reduce the rise time of the harvester by as much as 75% when compared to the finless square prism. The addition of the fins has no detrimental influence on the steady-state performance of the harvester. On the contrary, the steady-state voltage of the harvester can also be improved for some fin geometries.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)