Performance Evaluation of Flutter-Based Energy Harvester Under Different Vortex Flow Regimes: An Experimental Study

Flutter-based energy harnessing is a promising mean to power microelectronic devices located at remote locations, however, due to out of reach flow demand, marginal advancement is evident in this field. The present work evaluates energy harnessing potential of flutter under different flow fields generated with respect to different shapes of a bluff body. A proof of concept is demonstrated to employ flutter for energy harnessing activity at approachable ambient flow conditions. A test assembly of laminated sheet along with three different bluff bodies (triangular, square, D-shape) is considered. Initially, flow simulations are performed to visualize flow dynamics that qualitatively indicated that the pressure gradient due to downstream circulation and its distribution over the trailing plate are the key parameters to influence the flutter phenomenon. Subsequently, wind tunnel testing confirmed that presence of an upstream body reduces critical velocity significantly. Among all the cases, the D-shape body causes flutter at lowest flow velocity of 5.1 m/s which is 50% lower than 10.2 m/s observed in benchmark case of without upstream body. In order to harvest energy, piezoelectric material (MFC) is used and an output ranging from 0.89 to 1.16 mW across an optimum load resistance of 200 KΩ is observed corresponding to different cases. The D-shape body showed highest output at lowest flow velocity. In terms of ratio of output to input power, the D-shape, square and triangular shaped bodies showed 11.4, 6.7, and 4.6 times higher yield, respectively, when compared with the benchmark case study.