On the optimal performance and universal design curves of galloping energy harvesters

In this letter, we establish a universal relationship between a dimensionless version of the output power and the flow speed for galloping energy harvesters. This relationship yields a unique curve, which is only sensitive to the aerodynamic properties of the bluff body, but is, otherwise, invariant under any changes in the mechanical and electrical design parameters of the harvester. The curve permits a simple and direct comparative analysis of the energy harvesting performance of different bluff bodies so long that the other design parameters are kept constant. The universal curve is also shown to facilitate the optimization analysis, thereby providing significant insight into the optimal performance conditions.