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Sensors 2017, 17(9), 2100; https://doi.org/10.3390/s17092100

Autonomous Sensors Powered by Energy Harvesting from von Karman Vortices in Airflow

1
Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
2
Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
*
Author to whom correspondence should be addressed.
Received: 3 August 2017 / Revised: 5 September 2017 / Accepted: 8 September 2017 / Published: 13 September 2017
(This article belongs to the Special Issue Energy Harvesting Sensors for Long Term Applications in the IoT Era)
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Abstract

In this paper an energy harvesting system based on a piezoelectric converter to extract energy from airflow and use it to power battery-less sensors is presented. The converter is embedded as a part of a flexure beam that is put into vibrations by von Karman vortices detached from a bluff body placed upstream. The vortex street has been investigated by Computational Fluid Dynamics (CFD) simulations, aiming at assessing the vortex shedding frequency as a function of the flow velocity. From the simulation results the preferred positioning of the beam behind the bluff body has been derived. In the experimental characterization the electrical output from the converter has been measured for different flow velocities and beam orientations. Highest conversion effectiveness is obtained by an optimal orientation of the beam, to exploit the maximum forcing, and for flow velocities where the repetition frequency of the vortices allows to excite the beam resonant frequency at its first flexural mode. The possibility to power battery-less sensors and make them autonomous has been shown by developing an energy management and signal conditioning electronic circuit plus two sensors for measuring temperature and flow velocity and transmitting their values over a RF signal. A harvested power of about 650 μW with retransmission intervals below 2 min have been obtained for the optimal flow velocity of 4 m/s. View Full-Text
Keywords: autonomous sensors; flow induced vibrations; piezoelectric energy harvesting; von Karman vortices autonomous sensors; flow induced vibrations; piezoelectric energy harvesting; von Karman vortices
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Demori, M.; Ferrari, M.; Bonzanini, A.; Poesio, P.; Ferrari, V. Autonomous Sensors Powered by Energy Harvesting from von Karman Vortices in Airflow. Sensors 2017, 17, 2100.

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