Galloping-based piezo-aeroelastic energy harvester for wireless sensors to be installed on freight trains

Energy harvesting from galloping oscillations of a bluff body can be used to supply power to a wireless sensor. In this paper we investigate the possibility to use a galloping-based piezo-aeroelastic energy harvester to supply power to a wireless sensors network installed on a freight train to measure the accelerations in correspondence of axle boxes. The monitoring system will be used to detect possible deteriorations of the running conditions that, in the worst cases, can lead to the vehicle derailment. Unlike other applications in this case the air speed relative to the body is due to the train motion and, for typical freight trains and standard running conditions, is equal to about 20 m/s. In the paper we discuss the design of the harvester on the basis of the constrains due to the application. Preliminary aerodynamic tests shows the limitation of the classical quasi-steady theory of galloping as a consequence of the interaction with the vortex shedding phenomenon.