Effects of Downstream Structures on Aero Elastic Energy Harvesters From Wake-Induced Vibration

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Pakorn Uttayopas ◽  
Chawalit Kittichaikarn
Keyword(s):  
Cantilever Beam ◽  
Polyvinylidene Fluoride ◽  
Bluff Body ◽  
Electrical Energy ◽  
Load Resistance ◽  
High Amplitude ◽  
Triangular Prism ◽  
Energy Harvesters ◽  
Amplitude Vibration ◽  
And Behavior

An upstream cylindrical bluff body connected to a tip body via an aluminum cantilever beam was tested as energy harvester in a wind tunnel. The characteristics and behavior of the different tip body configurations and lengths of aluminum cantilever beam were studied to optimize design to extract wind energy. Particular attention was paid to measure vibration amplitude and frequency response as a function of reduced velocity. Dynamic response showed that the device's behavior was dependent on both tip body shape and cantilever beam length. Flow visualization tests showed that high amplitude vibration was obtainable when a vortex was fully formed on each side of the downstream tip body. This was exemplified in a symmetrical triangular prism tip body at L/D1 = 5, where its structure's vibration frequency was close to its natural frequency. At such configuration, electrical energy was captured using a polyvinylidene fluoride (PVDF) piezoelectric beam of different load resistances, where an optimized load resistance could be found for each Reynolds number. Although power output and efficiency obtained were considerably weak when compared to those of traditional wind turbine, the design merits further research to improve its performance under various circumstances.

scholarly journals Maximum Obtainable Energy Harvesting Power from Galloping-Based Piezoelectrics

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mohammad Yaghoub Abdollahzadeh Jamalabadi ◽  
Mostafa Safdari Shadloo ◽  
Arash Karimipour
Keyword(s):  
Energy Harvesting ◽  
Cantilever Beam ◽  
Bluff Body ◽  
Mechanical Energy ◽  
Average Power ◽  
Electrical Energy ◽  
Load Resistance ◽  
Nonlinear Motion ◽  
Rc Circuit ◽  
Deflection Limit

In this paper, the maximum obtainable energy from a galloping cantilever beam is found. The system consists of a bluff body in front of wind which was mounted on a cantilever beam and supported by piezoelectric sheets. Wind energy caused the transverse vibration of the beam and the mechanical energy of vibration is transferred to electrical charge by use of piezoelectric transducer. The nonlinear motion of the Euler–Bernoulli beam and conservation of electrical energy is modeled by lumped ordinary differential equations. The wind forces on the bluff body are modeled by quasisteady aeroelasticity approximation where the fluid and solid corresponding dynamics are disconnected in time scales. The linearized motion of beam is limited by its yield stress which causes to find a limit on energy harvesting of the system. The theory founded is used to check the validity of previous results of researchers for the effect of wind speed, tip cross-section geometry, and electrical load resistance on onset speed to galloping, tip displacement, and harvested power. Finally, maximum obtainable average power in a standard RC circuit as a function of deflection limit and synchronized charge extraction is obtained.

scholarly journals Non-linear piezoelectric fluidic energy harvesters: The mutual interaction of two oscillating cylinders

2020 ◽  
Vol 31 (20) ◽  
pp. 2378-2389
Author(s):  
Vahid Azadeh-Ranjbar ◽  
Yi Han ◽  
Niell Elvin ◽  
Yiannis Andreopoulos
Keyword(s):  
Cantilever Beam ◽  
Degrees Of Freedom ◽  
Bluff Body ◽  
Mutual Interaction ◽  
Bluff Bodies ◽  
Velocity Range ◽  
Freestream Velocity ◽  
Energy Harvesters ◽  
Piezoelectric Layers ◽  
Non Linear

The presence of a bluff body upstream of a cantilever beam promotes persistent, aero-elastic vibrations of the beam. Vortex-induced vibration in an array of two mutually interacting bluff bodies in such configurations undergoing two-degrees of freedom transverse oscillation has not been investigated before. In the present work, we have studied experimentally, the unsteady response of an array of two similar rigid cylinders, positioned side-by-side in reference to the freestream velocity, each one mounted on the upstream end of an elastic cantilever beam. By fitting the beams with piezoelectric layers, these configurations are converted to piezoelectric fluid energy harvesters (PFEH) that can extract small amounts of energy from the flow. Comparing the performance of linear (L-PFEH), non-linear (NL-PFEH), and a non-linear array (NLA-PFEH) of harvesters show that NLA-PFEH has the widest broadband operating velocity range and the greatest generated power followed by NL-PFEH and then L-PFEH. The maximum electric power output of NLA-PFEH was ~1000% greater than for NL-PFEH with a corresponding ~250% increase in the operating velocity range. Different cylinder configurations reveal the presence of hysteresis in the behavior of NLA-PFEH when the distance between the cylinders (so-called cylinder gap to diameter ratio), G/ D < 0.5. At large distances from each other ( G/ D ≥ 4), the two cylinders behave like independent, isolated harvester units with rather weak mutual interaction.

scholarly journals Enhancing Output Power of a Cantilever-Based Flapping Airflow Energy Harvester Using External Mechanical Interventions

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1499 ◽  
Author(s):  
Liuqing Wang ◽  
Dibin Zhu
Keyword(s):  
Flow Velocity ◽  
Output Power ◽  
Cantilever Beam ◽  
Power Output ◽  
Bluff Body ◽  
Energy Harvester ◽  
Magnetic Interaction ◽  
Electrical Energy ◽  
Increase Flow Velocity ◽  
Electrical Damping

This paper presents a flapping airflow energy harvester based on oscillations of a horizontal cantilever beam facing the direction of airflow. A wing is attached to the free end of a cantilever beam and a bluff body is placed in front of the wing from where vortex falls off, producing vortices under the wing and driving it to oscillate. An electromagnetic transducer is integrated to convert the flow induced vibration into electrical energy. This flapping energy harvester, however, may stop oscillating or vibrate in the second mode under high electrical damping, and thus may be unable to achieve its optimum performance. Simple yet effective mechanical interventions can be applied to the harvester to enhance its power output, i.e., to increase flow velocity and to apply external magnetic interaction. The effect of airflow velocities on output power was investigated experimentally and the results show that the energy harvester scavenges more power in airflow at higher Reynolds numbers (higher flow velocity at R e < 24,000). The external magnetic excitation is achieved though placing one magnet to the wing and another one above the wing to induce a repelling force, aiding the beam to oscillate in high electrical damping. Experimental results show that the power output can be enhanced by 30% when the magnet interaction is properly integrated.

Influence of Piezoelectric Energy Transfer on the Interwell Oscillations of Multistable Vibration Energy Harvesters

2019 ◽  
Vol 14 (3) ◽  
Author(s):  
Aravind Kumar ◽  
Shaikh Faruque Ali ◽  
A. Arockiarajan
Keyword(s):  
Energy Transfer ◽  
Electrical Energy ◽  
Potential Energy Function ◽  
Load Resistance ◽  
Theoretic Analysis ◽  
Mechanical Oscillator ◽  
Potential Wells ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Electromechanical Energy

This manuscript investigates the effect of nonconservative electromechanical energy transfer on the onset of interwell motions in multistable piezoelectric energy harvesters. Multistable piezoelectric energy harvesters have been proven to outperform their linear counterparts when they undergo interwell oscillations. The conditions for interwell oscillations in such harvesters are generally characterized in terms of their potential energy function. This is accurate for a stand-alone mechanical oscillator but when the piezoelectric patches and a load resistance are included, a part of the kinetic energy supplied to the system is converted into electrical energy. In this manuscript, the Melnikov necessary conditions for interwell oscillations are derived, considering the effect of this nonconservative piezoelectric energy transfer. Through Melnikov theoretic analysis, it is shown that in a tristable harvester with all the three potential wells having the same depth, a higher excitation level is required to enable exits from the middle well to the outer wells when compared to the exits from the outer wells to the middle well. This is in stark contrast to a stand-alone tristable mechanical oscillator wherein interwell motions are simultaneously enabled for all the wells having the same depth.

Constraint Effects on Torque-Actuated Bistable Energy Harvesters

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Daniel A. Porter ◽  
Thomas A. Berfield
Keyword(s):  
Boundary Conditions ◽  
Polyvinylidene Fluoride ◽  
Load Resistance ◽  
Resonant Frequencies ◽  
Energy Harvesters ◽  
Optimal Load ◽  
3D Printed ◽  
Frequency Sweeps ◽  
Constraint Effects ◽  
Bistable Device

AbstractThe effect of boundary conditions on a bistable device that buckles into an “S” shape and utilizes polyvinylidene fluoride is evaluated. Four permutations with different center constraints are the perfectly pinned circular steel, rigid glued circular steel, 3×1 and 5×1 3D printed rectangle polylactic acid prototypes. Using a load of 30 MΩ, which was close to the optimal load resistance, frequency sweeps in the forward and reverse directions indicated different nonlinearities depending on if the device is buckled or not. Peak resonant frequencies for the devices are around 18 to 30 Hz with bistable actuation occurring as low as 0.3

Modeling of Piezoelectric Acoustic Energy Harvester

2014 ◽  
Vol 695 ◽  
pp. 757-760 ◽  
Author(s):  
Susilo Sidik ◽  
Azma Putra ◽  
Swee Leong Kok
Keyword(s):  
Energy Harvesting ◽  
Acoustic Waves ◽  
Piezoelectric Materials ◽  
Maximum Output Power ◽  
Flexural Vibration ◽  
Electrical Energy ◽  
Load Resistance ◽  
Acoustic Energy ◽  
Maximum Output ◽  
Energy Harvesters

Harvesting ambient acoustics for conversion into usable electricity provides a potential power source for emerging technologies including wireless sensor networks. Acoustic energy harvesters convert energy from acoustic waves to electrical energy. Here acoustic energy harvesting from ambient noise utilizing flexural vibration of a flexible panel is investigated. A flexural vibration from the panel is use to extract more energy from the ambient acoustics where piezoelectric materials of PVDF films are attached around the plate edges. This study found that the energy harvesting can be obtained with a maximum output power of 480 pW at 400 kΩ load resistance.

High-output piezoelectric energy harvester using tapered beam with cavity

2017 ◽  
Vol 29 (5) ◽  
pp. 800-815 ◽  
Author(s):  
S Srinivasulu Raju ◽  
M Umapathy ◽  
G Uma
Keyword(s):  
Analytical Model ◽  
Cantilever Beam ◽  
Energy Harvester ◽  
Structural Parameters ◽  
Beam Theory ◽  
Electrical Energy ◽  
Tapered Beam ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Piezoelectric Structure

Energy harvesting using cantilever-based piezoelectric structure is most popular for harvesting electrical energy from ambient vibrations. Efforts are also made to maximize the harvester power by means of tailoring the structural parameters of the cantilever beam. This article proposes a method to maximize the harvester voltage from the cantilever-based piezoelectric energy harvester by means of tailoring the structure of the cantilever, to have a tapering in width, thickness and in both width and thickness (double taper). It is also proposed to introduce rectangular and trapezoidal cavities in the tapered energy harvesters to further maximize the harvester voltage. The analytical model of the proposed harvesters is developed using Euler–Bernoulli beam theory, and its free vibration solution is analysed using Bessel functions. The energy harvesters are fabricated and experimentally evaluated for its performance. It is concluded from the results of analytical model and experimentation that width, thickness and double-tapered beam increases the harvester voltage by 35.6%, 84.8% and 126.6%, respectively, as compared to the energy harvester designed with uniform cantilever beam. Among all the energy harvesters proposed in this article, the maximum voltage is generated from the double-tapered beam with trapezoidal cavity. The experimental results are in close agreement with the results obtained from the analytical model.

Study of Energy Harvesting Performance of Wet-Stretched PVDF Nanofibers

2016 ◽  
Author(s):  
Raghid Najjar ◽  
Yi Luo ◽  
Xiao Hu ◽  
Vince Beachley ◽  
Wei Xue
Keyword(s):  
Energy Harvesting ◽  
Polyvinylidene Fluoride ◽  
Low Cost ◽  
Mechanical Energy ◽  
Body Movement ◽  
Electrical Energy ◽  
Electrospinning Process ◽  
Energy Harvesters ◽  
Portable Electronics ◽  
Wearable Systems

An average human body produces a large amount of energy throughout the day. A significant portion of this energy is utilized as mechanical energy. Body movement such as footfalls and arm swings can produce enough energy to power portable electronics using mechanical-to-electrical energy harvesters. These devices should be small, light, portable, and flexible. Polyvinylidene fluoride (PVDF) has shown a high biocompatibility and is a suitable candidate for energy harvesting applications. Moreover, PVDF can be produced in large quantities while still maintaining a low cost. Electrospinning is a common process used to prepare PVDF nanofibers. Here we introduce a novel technique called wet-stretched electrospinning to further increase the amount of energy generated by the PVDF devices. Our initial results show that the wet-stretched nanofibers outperform the regular PVDF nanofibers by up to 12 times under similar conditions. These promising results suggest that the proposed method has great potential to be utilized as a major improvement from the traditional electrospinning process of PVDF. These findings are significant and are especially pertinent to the field of energy harvesters designed for powering medical devices or wearable systems.

scholarly journals Load Resistance Optimization of a Broadband Bistable Piezoelectric Energy Harvester for Primary Harmonic and Subharmonic Behaviors

2021 ◽  
Vol 13 (5) ◽  
pp. 2865 ◽  
Author(s):  
Sungryong Bae ◽  
Pilkee Kim
Keyword(s):  
Energy Harvester ◽  
Load Resistance ◽  
Oscillation Period ◽  
Ambient Vibration ◽  
Ambient Vibrations ◽  
Frequency Dependency ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Bistable Energy Harvester

In this study, optimization of the external load resistance of a piezoelectric bistable energy harvester was performed for primary harmonic (period-1T) and subharmonic (period-3T) interwell motions. The analytical expression of the optimal load resistance was derived, based on the spectral analyses of the interwell motions, and evaluated. The analytical results are in excellent agreement with the numerical ones. A parametric study shows that the optimal load resistance depended on the forcing frequency, but not the intensity of the ambient vibration. Additionally, it was found that the optimal resistance for the period-3T interwell motion tended to be approximately three times larger than that for the period-1T interwell motion, which means that the optimal resistance was directly affected by the oscillation frequency (or oscillation period) of the motion rather than the forcing frequency. For broadband energy harvesting applications, the subharmonic interwell motion is also useful, in addition to the primary harmonic interwell motion. In designing such piezoelectric bistable energy harvesters, the frequency dependency of the optimal load resistance should be considered properly depending on ambient vibrations.

Dynamic Response of Spiral Cantilever Undergoing Magnetic Coupling

2014 ◽  
Vol 14 (08) ◽  
pp. 1440021
Author(s):  
Xiaoling Bai ◽  
Yumei Wen ◽  
Ping Li ◽  
Jin Yang ◽  
Xiao Peng ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Cantilever Beam ◽  
Magnetic Force ◽  
Coupling Effect ◽  
Magnetic Coupling ◽  
Resonant Frequencies ◽  
Energy Harvesters ◽  
Magnetic Transducer ◽  
Underlying Mechanisms ◽  
Tip Mass

Cantilever beams have found intensive and extensive uses as underlying mechanisms for energy transduction in sensors as well as in energy harvesters. In magnetoelectric (ME) transduction, the underlying cantilever beam usually will undergo magnetic coupling effect. As the beam itself is either banded with magnetic transducer or magnets, the dynamic motion of the cantilever can be modified due to the magnetic force between the magnets and ME sensors. In this study, the dynamic response of a typical spiral cantilever beam with magnetic coupling is investigated. The spiral cantilever acts as the resonator of an energy harvester with a tip mass in the form of magnets, and a ME transducer is positioned in the air gap and interacts with the magnets. It is expected that this spiral configuration is capable of performing multiple vibration modes over a small frequency range and the response frequencies can be magnetically tunable. The experimental results show that the magnetic coupling between the magnets and the transducer plays a favorable role in achieving tunable resonant frequencies and reducing the frequency spacings. This will benefits the expansion of the response band of a device and is especially useful in energy harvesting.

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