Power harvesting by electromagnetic coupling from wind-induced limit cycle oscillations

Abstract

Recent developments of low-power microprocessors open to new applications such as wireless sensor networks (WSN) with the consequent problem of autonomous powering. For this purpose, a possible strategy is represented by energy harvesting from wind or other flows exploiting fluid–structure interactions. In this work, we present an updated picture of a flutter-based device characterized by fully passive dynamics and a simple constructive layout, where limit cycle oscillations are undergone by an elastically bounded wing. In this case, the conversion from mechanical to electrical energy is performed by means of an electromagnetic coupling between a pair of coils and magnets. A centimetric-size prototype is shown to harvest energy from low wind velocities (between 2 and 4 m s−1), reaching a power peak of 14 mW, representing a valuable amount for applications related to WSN. A mathematical description of the nonlinear dynamics is then provided by a quasi-steady phenomenological model, revealing satisfactory agreement with the experimental framework within a certain parametric range and representing a useful tool for future optimizations.

On the nonlinear dynamics of self-sustained limit-cycle oscillations in a flapping-foil energy harvester

“…Several implementations of this technology with varying levels of success and efficiency are reviewed in Young et al [6] and Xiao & Zhu [7]. Notably, Boragno et al [41] and Boccalero et al [42] have developed an efficient realization of the energy harvester through electromagnetic coupling in the Reynolds number range between 5, 000-10, 000 for micro-power harvesting. They have also developed a simple low-order model of the system for analytical investigations, though this does not account for the nonlinear aerodynamics.…”

“…The unsteady aerodynamics and associated nonlinearities in this Reynolds number regime are fairly well understood since they have been the subject of extensive investigation [31,32,34,33,35,43,44,45] in the last decade (inspired by MAV design). This Reynolds number also falls in an ideal regime where the shed leading-edge vortices are coherent [42]. The effect of various aerodynamic and structural parameters on the 2DOF system's passive response characteristics (such as amplitude and frequency) and power generation potential are investigated in detail.…”

Constructive interference in a network of elastically-bounded flapping plates

“…16. Experiments were performed using the wind-tunnel facility at Physics Department of the University of Genoa, whose characteristic parameters, along with the procedure used to acquire the motion of flapping wings in time, have been described in previous works [26,28,30]. Each of the three components is similar to the devices already presented in Refs.…”

“…In this work, we focus on an aeroelastic system based on elastically-anchored plates experiencing a fluttering instability when invested by laminar flow, giving rise to finite-amplitude limit cycle oscillations (LCOs) and flapping motions [26][27][28][29][30]. Previous related work addressed the identification of the critical threshold for sustained flapping [27,28] and a first characterization of the postcritical behaviour for a representative configuration of the real device [29], as well as the development of an experimental prototype equipped for energy extraction by electromagnetic coupling [30]. Overall, we aim at developing EH devices of centimetric size able to extract electrical power O(mW) in low wind conditions (i.e., U < 5 m/s).…”

Universal flapping states of elastic fibers in modulated turbulence

“…The interaction between elastic objects and fluid flows plays an essential role in a variety of both fundamental and applied problems, ranging from biological (e.g., mucus-cilia or red blood cells hydrodynamics) 1-3 and environmental processes (e.g., flow in flexible canopies and plant reconfiguration) [4][5][6][7] to engineering applications (e.g., energy harvesting and flow control) [8][9][10][11][12][13][14] . Despite the great advancement of research in these fields, the available knowledge on such nontrivial phenomena mostly concerns the situation where the flow is laminar [15][16][17][18] , whereas the interaction between elastic objects and turbulence has started to be understood only more recently [19][20][21][22][23] .…”