Flow Energy Harvesters With a Nonlinear Restoring Force

2014 ◽  
Author(s):  
Ali H. Alhadidi ◽  
Amin Bibo ◽  
Mohammed F. Daqaq
Keyword(s):  
Bluff Body ◽  
Energy Harvester ◽  
Restoring Force ◽  
Energy Harvesters ◽  
Flow Energy ◽  
Nonlinear Restoring Force ◽  
Aerodynamic Loading ◽  
Lumped Parameter ◽  
Piezoelectric Cantilever ◽  
Different Shapes

This ppppaper examines the performance of a galloping energy harvester possessing a nonlinear restoring force. To achieve this goal, a flow energy harvester consisting of a piezoelectric cantilever beam augmented with a square-sectioned bluff body at the free end is considered. Two magnets located near the tip of the bluff body are used to introduce the nonlinearity which strength and nature can be altered by changing the distance between the magnets. A lumped-parameter aero-electromechanical model adopting the quasi-steady assumption for aerodynamic loading is presented and utilized to numerically simulate the harvester’s response. Wind tunnel tests are also performed to validate the numerical simulations by conducting upward and downward wind velocity sweeps. Results comparing the relative performance of several harvesters with potential functions of different shapes demonstrate that a mono-stable potential function with a hardening restoring force can outperform all other configurations.

A broadband flow energy harvester induced by the wake of a bluff body

2021 ◽  
Author(s):  
Wen-An Jiang ◽  
Xin-dong Ma ◽  
Yong Wang ◽  
Mao Liu ◽  
Li-qun Chen ◽  
...  
Keyword(s):  
Bluff Body ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Analytical Data ◽  
Degree Of Freedom ◽  
Nonlinear Flow ◽  
Physical Parameters ◽  
Restoring Force ◽  
Flow Energy ◽  
Two Degree Of Freedom

Abstract Wake galloping energy harvesting have been extensively developed to scavenge flow energy from vortex-induced oscillations. Hence, the wake-galloping harvester only has a natural frequency which leads to a very narrow bandwidth. Therefore, it does not operate well under the wide region of shedding frequencies in variable wind speed. To overcome the vital issue, this paper we explored a novel two-degree-of-freedom nonlinear flow energy harvester to collect flow energy induced by the wake of a bluff body. The nonlinear restoring force is realized by using a repulsive magnetic force between two cuboid-shaped permanent magnets, and the electromechanical coupling equations is presented. Based on the method of harmonic balance, the electromechanical governing equations is decoupled, and the first order harmonic solutions are implemented. The modulation equations are established, the amplitude-frequency figures of displacement and voltage are depicted with different detuning parameters. The superiority of the presented energy harvester is contrasted with the single-degree-of-freedom linear and nonlinear cases, the results revealed that the two-degree-of-freedom nonlinear scheme can enhance the bandwidth of flow energy capture. The effect of physical parameters on the scavenged power is discussed. The accuracy and efficiency of the approximate analytical data are examined by numerical simulations.

Exploiting Bi-Stability to Enhance Energy Capture From Turbulent Flows

2015 ◽  
Author(s):  
Ali H. Alhadidi ◽  
Mohammed F. Daqaq
Keyword(s):  
Wind Tunnel ◽  
Turbulent Flows ◽  
Output Power ◽  
Turbulence Intensity ◽  
Bluff Body ◽  
Reynolds Numbers ◽  
Restoring Force ◽  
Energy Capture ◽  
Energy Harvesters ◽  
Piezoelectric Cantilever

This paper investigates utilizing a nonlinear (bi-stable) restoring force to enhance the transduction of galloping energy harvesters in turbulent flows. To that end, a harvester consisting of a piezoelectric cantilever beam augmented with a square-sectioned bluff body at the free end is considered. Two repulsive magnets located at the tip of the beam are used to introduce the bi-stable restoring force. Turbulence is generated in a wind tunnel using static-grid structures located in the upstream of the bluff body. Three different mesh screens with square bars are designed with different bar and mesh widths to control the Reynolds numbers and associated turbulence intensity. A series of wind tunnel tests are then used to experimentally investigate the response of the harvester with and without the tip magnets. Results demonstrate that the bi-stable restoring force can be used to improve the output power of the harvester for sufficiently large turbulence intensities.

Utilizing Bi-Stability to Improve the Performance of Wake-Galloping Energy Harvesters in Unsteady Flow

2016 ◽  
Author(s):  
Ali H. Alhadidi ◽  
Mohammed F. Daqaq ◽  
Hamid Abderrahmane
Keyword(s):  
Wind Tunnel ◽  
Unsteady Flow ◽  
Output Power ◽  
Bluff Body ◽  
Unsteady Flows ◽  
Reynolds Numbers ◽  
Flow Conditions ◽  
Restoring Force ◽  
Energy Harvesters ◽  
Piezoelectric Cantilever

This paper investigates exploiting a bi-stable restoring force to enhance the transduction of wake-galloping energy harvesters in unsteady flows. To that end, a harvester consisting of a piezoelectric cantilever beam augmented with a square-sectioned bluff body at the free end is considered. Two repulsive magnets located at the tip of the beam are used to introduce the bi-stable restoring force. Unsteadiness is generated in a wind tunnel using static-grid structures located in the upstream of the bluff body. Three different mesh screens with square bars are designed with different bar and mesh widths to control the Reynolds numbers and associated unsteadiness. A series of wind tunnel tests are then used to experimentally investigate the response of the harvester with and without the tip magnets. Results demonstrate that the bi-stable restoring force can be used to improve the output power of the harvester under unsteady flow conditions.

Exploiting a nonlinear restoring force to improve the performance of flow energy harvesters

2015 ◽  
Vol 117 (4) ◽  
pp. 045103 ◽  
Author(s):  
Amin Bibo ◽  
Ali H. Alhadidi ◽  
Mohammed F. Daqaq
Keyword(s):  
Restoring Force ◽  
Energy Harvesters ◽  
Flow Energy ◽  
Nonlinear Restoring Force

Experimental Study of a Self-Excited Piezoelectric Energy Harvester

2010 ◽  
Author(s):  
Hu¨seyin Dog˘us¸ Akaydın ◽  
Niell Elvin ◽  
Yiannis Andreopoulos
Keyword(s):  
Electrical Power ◽  
Natural Mode ◽  
Structural Vibrations ◽  
Energy Harvesters ◽  
Flow Energy ◽  
Piezoelectric Energy ◽  
Voltage Output ◽  
Aerodynamic Properties ◽  
Piezoelectric Cantilever ◽  
Measured Strain

In the present experimental work, we explore the possibility of using piezoelectric based fluid flow energy harvesters. These harvesters are self-excited and self-sustained in the sense that they can be used in steady uniform flows. The configuration consists of a piezoelectric cantilever beam with a cylindrical tip body which promotes sustainable, aero-elastic structural vibrations induced by vortex shedding and galloping. The structural and aerodynamic properties of the harvester alter the vibration amplitude and frequency of the piezoelectric beam and thus its electrical output. This paper presents results of energy-harvesting tests with one configuration of such a self-excited piezoelectric harvester using a PZT bimorph. In addition to the electrical voltage output, the strain on the surface of beam close to its clamped tip was also measured The measured strain and voltage output were perfectly correlated in the frequency range containing the first natural mode of vibration of the system. It was observed that about 0.24 mW of electrical power can be attained with this harvester in a uniform flow of 28 m/s.

An Experimental Investigation Into the Performance of a T-Shaped Piezoelectric Flow Energy Harvester

2013 ◽  
Author(s):  
P. B. Jain ◽  
M. R. Cacan ◽  
S. Leadenham ◽  
C. De Marqui ◽  
A. Erturk
Keyword(s):  
Geometric Parameter ◽  
Energy Harvester ◽  
Mechanical Response ◽  
Electrical Power ◽  
Response Spectra ◽  
Load Resistance ◽  
Flow Speed ◽  
Research Field ◽  
Flow Energy ◽  
Piezoelectric Cantilever

The harvesting of flow energy by exploiting aeroelastic and hydroelastic vibrations has received growing attention over the last few years. The goal in this research field is to generate low-power electricity from flow-induced vibrations of scalable structures involving a proper transduction mechanism for wireless applications ranging from manned/unmanned aerial vehicles to civil infrastructure systems located in high wind areas. The fundamental challenge is to enable geometrically small flow energy harvesters while keeping the cut-in speed (lowest flow speed that induces persistent oscillations) low. An effective design with reduced cut-in speed is known to be the T-shaped cantilever arrangement that consists of a horizontal piezoelectric cantilever with a perpendicular vertical beam attachment at the tip. The direction of incoming flow is parallel to the horizontal cantilever and perpendicular to the vertical and symmetric tip attachment. Vortex-induced vibration resulting from flow past the tip attachment is the source of the aeroelastic response. For a given width of the T-shaped harvester with fixed thickness parameters, an important geometric parameter is the length ratio of the tip attachment to the cantilever. In this paper we investigate the effect of this geometric parameter on the piezoaeroelastic response of a T-shaped flow energy harvester. A controlled desktop wind tunnel system is used to characterize the electrical and mechanical response characteristics for broad ranges of flow speed and electrical load resistance using different vertical tip attachment lengths for the same horizontal piezoelectric cantilever. The variations of the electrical power output and cut-in speed with changing head length are reported along with an investigation into the electroaeroelastic frequency response spectra.

Synchronization of Cantilevers Arranged in Line of a Piezoelectric Energy Harvester

2015 ◽  
Author(s):  
Max Spornraft ◽  
Norbert Schwesinger ◽  
Shlomo Berger
Keyword(s):  
Energy Harvesting ◽  
Bluff Body ◽  
Energy Harvester ◽  
Phase Synchronization ◽  
Vibrational Excitation ◽  
Line Energy ◽  
Mechanical Coupling ◽  
Piezoelectric Energy ◽  
Piezoelectric Cantilever ◽  
The Right

Synchronization opens further ways to improve cantilever-based energy harvesting arrays in view of power output, easier rectification and scaling. Objective of this study is to investigate the synchronization behavior of a cantilever-array based energy harvesting systems. Thereby, synchronization is achieved by mechanical coupling through a so-called “overhang”. Nakajima et al. [1] and Wang et al. [2] already verified this principle for the synchronization of two and three cantilevers, but at constant vibrational excitation. Regarding energy harvesting, no application of this method is presently available. In this paper, we investigate the synchronization behavior of a piezoelectric cantilever-line energy harvester in airflow. The design of the energy harvester bases upon a piezoelectric cantilever-line and a common bluff body, arranged upstream. To investigate synchronization of the cantilevers, three commonly available piezoelectric bimorphs were employed to study synchronization. Mounted on a common bluff body, the effect of overhang material and position was studied. Therefore, different constellations were examined by impulse excitation as well as vortex-induced vibration in a wind channel. In several measurements, we found arrangements and parameters allowing for an in-phase synchronization of neighborly cantilevers of the line. The knowledge gained allows for a direct electrical connection of piezoelectric cantilevers with just one single rectifier unit. Cantilevers coupled with overhangs arranged in the right order oscillate with the same frequency and phase, i.e. without any charge cancellations. This knowledge opens ways to develop basic design rules for the synchronization of cantilevers.

New Insights Into the Performance and Optimization of Galloping Flow Energy Harvesters

2014 ◽  
Author(s):  
Amin Bibo ◽  
Mohammed F. Daqaq
Keyword(s):  
Bluff Body ◽  
Lumped Parameter Model ◽  
Combined Loading ◽  
Design Parameters ◽  
Optimal Harvesting ◽  
Universal Curve ◽  
Response Curves ◽  
Energy Harvesters ◽  
Flow Energy ◽  
Mechanical Transduction

This paper presents a generalized formulation, analysis, and optimization of energy harvesters subjected to galloping and base excitations. The harvester consists of a cantilever beam with a bluff body attached at the free end. A nondimensional lumped-parameter model which accounts for the combined loading and different electro-mechanical transduction mechanisms is presented. The aerodynamic loading is modeled using the quasi-steady assumption with polynomial approximation. A nonlinear analysis is carried out and an approximate analytical solution is obtained. A dimensional analysis is performed to identify the important parameters that affect the system’s response. It is shown that the response curves of the harvester can be generated in terms of only three dimensionless loading parameters. These curves can serve as a complete design guide for scaling and optimizing the performance of galloping-based harvesters. As a special case study, a harvester subjected to only galloping excitations is analyzed. It is shown that, for a given shape of the bluff body and under quasi-steady flow conditions, the harvester’s dimensionless response can be described by a single universal curve irrespective to the geometric, mechanical, and electrical design parameters of the harvester. The universal curve is utilized to obtain the optimal harvesting circuit design parameters, that minimize the cut-in wind speed and maximize the output power, and predict the harvester’s total conversion efficiency.

Fabrication and analytical modeling of transverse mode piezoelectric energy harvesters

2012 ◽  
Vol 1397 ◽  
Author(s):  
Seon-Bae Kim ◽  
Jung-Hyun Park ◽  
Seung-Hyun Kim ◽  
Hosang Ahn ◽  
H. Clyde Wikle ◽  
...  
Keyword(s):  
Output Power ◽  
Analytical Modeling ◽  
Energy Harvester ◽  
Power Conversion ◽  
Transverse Mode ◽  
Modified Model ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Interdigital Electrodes ◽  
Piezoelectric Cantilever

ABSTRACTA transverse (d33) mode piezoelectric cantilever was fabricated for energy harvesting. Various dimensions of interdigital electrodes (IDE) were deposited on a piezoelectric layer to examine the effects of electrode design on the performance of energy harvesters. Modeling was performed to calculate the output power of the devices. The estimation was based on Roundy’s analytical modeling derived for a d31 mode piezoelectric energy harvester (PEH). In order to apply the Roundy’s model to d33 mode PEH, the IDE configuration was converted to the area of top and bottom electrodes (TBE). The power conversion in d33 mode PEH was commonly estimated by the product of piezoelectric layer’s thickness and finger electrode’s length. In addition, the spacing between fingers was regarded as gap between top and bottom electrodes. However, the output power in a transverse mode PEH increases continuously with the increase of finger spacing, which does not correspond to experimental results. In this research, the dimension of IDE was converted to that of TBE using conformal mapping, and variation of power of PEH was remodeled. The modified model suggests that the maximum power in a transverse mode PEH is obtained when the finger spacing is identical with effective finger spacing. The output power then decreases when finger spacing is larger than effective finger spacing. The decrease of efficiency may result from insufficient degree of poling and increased charged defect with increasing finger spacing.

Modeling and Characterization of a Piezoelectric Energy Harvester Under Combined Aerodynamic and Base Excitations

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Amin Bibo ◽  
Abdessattar Abdelkefi ◽  
Mohammed F. Daqaq
Keyword(s):  
Bluff Body ◽  
Energy Harvester ◽  
Constitutive Relations ◽  
Equations Of Motion ◽  
Primary Resonance ◽  
Beam Theory ◽  
Combined Loading ◽  
Response Behavior ◽  
Piezoelectric Energy ◽  
Piezoelectric Cantilever

This paper develops and validates an aero-electromechanical model which captures the nonlinear response behavior of a piezoelectric cantilever-type energy harvester under combined galloping and base excitations. The harvester consists of a thin piezoelectric cantilever beam clamped at one end and rigidly attached to a bluff body at the other end. In addition to the vibratory base excitations, the beam is also subjected to aerodynamic forces resulting from the separation of the incoming airflow on both sides of the bluff body which gives rise to limit-cycle oscillations when the airflow velocity exceeds a critical value. A nonlinear electromechanical distributed-parameter model of the harvester under the combined excitations is derived using the energy approach and by adopting the nonlinear Euler–Bernoulli beam theory, linear constitutive relations for the piezoelectric transduction, and the quasi-steady assumption for the aerodynamic loading. The resulting partial differential equations of motion are discretized and a reduced-order model is obtained. The mathematical model is validated by conducting a series of experiments at different wind speeds and base excitation amplitudes for excitation frequencies around the primary resonance of the harvester. Results from the model and experiment are presented to characterize the response behavior under the combined loading.

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