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

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.

Interrogation Techniques and Interface Circuits for Coil-Coupled Passive Sensors

“…Suitable energy converters have been developed to transform the harvested energy into electrical energy using different principles, like piezoelectric [ 1 , 2 ], electromagnetic [ 3 ], thermoelectric [ 4 ] or pyroelectric [ 5 , 6 ] effects. Depending on the input source, the converted power can be sufficient to supply, continuously or intermittently, one or more sensing devices, which can transmit the measurement information through a radio frequency (RF) link to a receiving and supervising unit, thus creating a completely autonomous system without the need for power supply and cabling [ 7 ].…”

Modeling and Efficiency Analysis of a Piezoelectric Energy Harvester Based on the Flow Induced Vibration of a Piezoelectric Composite Pipe

“…This kind of alternating vortices will impose alternating forces upon the flexible piezoelectric composite eel and thus induce vibration in the eel, which can be used to extract energy from the fluid flow. Some other mechanisms are also incorporated into the flow energy harvesting system, such as the coupled mode flutter of airfoils, [9] the vortex-induced vibrations of rigid bodies inside steady flow, [10,11] and the galloping instabilities of flexible structures [12], etc. In addition, based on the profound research of the flapping dynamics of a flag in a uniform stream, [13,14] the utilization of compliant beams or plates to directly harvest energy from steady state fluid flow has received much attention, [15,16] with multiple aspects of the system investigated [17,18,19,20,21].…”

La-CTP: Loop-Aware Routing for Energy-Harvesting Wireless Sensor Networks

“…Recently researchers have attempted to employ the environmental (ambient) energy to drive the wireless sensor nodes. A variety of environmental energy sources exist in nature, such as solar energy, wind energy, RF energy, vibration energy, and hydrokinetic energy [ 3 , 4 , 5 , 6 , 7 ]; some of them are renewable and can be easily captured and stored in rechargeable battery. By harvesting such renewable environmental energy to power wireless sensor nodes, the users do not need to frequently replace (or manually charge) the battery modules of their nodes, and then they could achieve longer or even perpetual system operation [ 8 , 9 , 10 , 11 ].…”