Development of a Hybrid Harvester for Collecting Energy From Wind and Vibrations in Light Vehicles

Abstract A bicycle experiences road-excited vibrations and is impacted by a wind flow. Both these phenomena can be exploited for energy harvesting. Previous research showed that the tuning of the harvester to road-excited vibrations requires a low natural frequency that can be achieved by means of a large tip mass. This tip mass can be used to equip the harvester with a bluff body for energy harvesting from wind-excited vibrations. The interaction between the bluff body and the wind flow generates a vortex shedding phenomenon that at a certain wind velocity is able to excite the harvester in resonance condition. Moreover, the turbulence of the incoming wind is able to excite the bluff body in the high velocity range (buffeting excitation). The paper deals with mathematical and experimental analyses for the development of a hybrid piezoelectric harvester able to scavenge energy from road-excited vibrations and wind. A multi-physical mathematical model that takes into account the couplings between the mechanical, electrical and fluid domains is developed. The coupled equations are solved in Matlab and are used for the harvester design. Two prototypes are developed and tested. The results of experimental tests carried out in a wind tunnel and in open space show the potentialities of the proposed harvester layout.