A Smart Device for Harnessing Energy From Aerodynamic Flow Fields

2009 ◽  
Author(s):  
Daniel St. Clair ◽  
Christopher Stabler ◽  
Mohammed F. Daqaq ◽  
Jian Luo ◽  
Gang Li
Keyword(s):  
Wind Energy ◽  
Cantilever Beam ◽  
Flow Rate ◽  
Excitation Frequency ◽  
Volumetric Flow Rate ◽  
Smart Device ◽  
Electric Load ◽  
Energy Harvesters ◽  
Air Chamber ◽  
Piezoelectric Cantilever

In this work, inspired by music playing harmonicas, we conduct a conceptual investigation of a coupled aero-electromechanical system for wind energy harvesting. The system consists of a piezoelectric cantilever unimorph structure embedded within an air chamber to mimic the vibration of the reeds in a harmonica when subjected to air flow. In principle, when wind blows into the air chamber, the air pressure in the chamber increases and bends the cantilever beam opening an air path between the chamber and the environment. When the volumetric flow rate of air past the cantilever is large enough, the energy pumped into the structure via the nonlinear pressure forces offset the intrinsic damping in the system setting the beam into self-sustained limit-cycle oscillations. These oscillations induce a periodic strain in the piezoelectric layer which produces a voltage difference that can be channeled into an electric load. Unlike traditional vibratory energy harvesters where the excitation frequency needs to match the resonant frequency of the device for efficient energy extraction, the nonlinearly coupled aero-elasto dynamics of this device guarantees autonomous vibration of the cantilever beam near its natural frequency as long as the volumetric flow rate is larger than a certain threshold. Experimental results are presented to demonstrate the ability of this device to harvest wind energy under normal wind conditions.

A Nonlinear Electromechanical Model of a Scalable Self-Excited Wind Energy Harvester

2010 ◽  
Author(s):  
Amin Bibo ◽  
Daniel St. Clair ◽  
Venkata R. Sennakesavababu ◽  
Gang Li ◽  
Mohammed F. Daqaq
Keyword(s):  
Wind Energy ◽  
Electric Power ◽  
Limit Cycle ◽  
Flow Rate ◽  
Mechanical Model ◽  
Energy Harvester ◽  
Volumetric Flow Rate ◽  
Limit Cycle Oscillations ◽  
Electromechanical Model ◽  
Piezoelectric Beam

We present and validate a nonlinear aero-electro-mechanical model that describes the response of a scalable self-excited wind energy harvester. Similar to music-playing harmonica that create tones via oscillations of reeds when subjected to air blow, the proposed device uses flow-induced self-excited oscillations of a piezoelectric beam embedded within a cavity to generate electric power. Specifically, when the volumetric flow rate of air past the beam exceeds a certain threshold, the energy pumped into the structure via nonlinear pressure forces offsets the intrinsic damping in the system setting the beam into self-sustained limit-cycle oscillations. The vibratory energy is then converted into electricity through principles of piezoelectricity.

Geometry Effects on the Flow Rectification of a Dynamic Micro Diffuser: A Numerical Investigation

Volume 4 ◽  
2004 ◽  
Author(s):  
Chen-Li Sun ◽  
Kun Hao Huang
Keyword(s):  
Pressure Gradient ◽  
Numerical Investigation ◽  
Flow Rate ◽  
Excitation Frequency ◽  
Fluid Flows ◽  
Volumetric Flow Rate ◽  
Reynolds Numbers ◽  
Pressure Amplitude ◽  
Half Angle ◽  
Geometry Effects

In this study, a numerical investigation is presented to characterize the geometry effects on the transient behaviors of a micro diffuser pump. Four parameters of the dynamic diffuser pump, half-angle, depth, length, and excitation frequency, are considered. A time-dependent sinusoidal pressure with fixed pressure amplitude (200 Pa) is applied at the inlet as the boundary condition. The results from the numerical analysis have been quantified in terms of average volumetric flow rate. Despite the corresponding low Reynolds numbers (Re < 10), circulation is observed for all tested half-angles. When the direction of pressure gradient switches, fluid flows against the pressure gradient and triggers flow separation near wall. The vortex then migrates from wall toward the center of diffuser with time. For 5° ≤ θ ≤ 35°, diffusers with larger half-angles show better rectification effects. For θ gt; 35°, net flow rate is nearly independent of half-angle. Shorter and deeper diffuser results in larger net flow rate regardless of its half-angle. The increase of the excitation frequency diminishes the flow rectification in micro diffuser.

A self-tunable wind energy harvester utilising a piezoelectric cantilever beam with bluff body under transverse galloping for field deployment

2021 ◽  
Vol 245 ◽  
pp. 114559
Author(s):  
Yee Yan Lim ◽  
Ricardo Vasquez Padilla ◽  
Andreas Unger ◽  
Rodrigo Barraza ◽  
Ahmed Mostafa Thabet ◽  
...  
Keyword(s):  
Wind Energy ◽  
Cantilever Beam ◽  
Bluff Body ◽  
Energy Harvester ◽  
Piezoelectric Cantilever ◽  
Field Deployment ◽  
Transverse Galloping

Reduced-Order Modeling of Energy Harvesters

2009 ◽  
Author(s):  
Thiago Seuaciuc-Oso´rio ◽  
Mohammed F. Daqaq
Keyword(s):  
Output Power ◽  
Cantilever Beam ◽  
Electromechanical Coupling ◽  
Single Mode ◽  
Exact Expression ◽  
Reduced Order ◽  
Energy Harvesters ◽  
Piezoelectric Cantilever ◽  
Design Values ◽  
Ritz Procedure

This work addresses the accuracy and convergence of reduced-order models (ROMs) of energy harvesters. Two types of energy harvesters are considered, a magnetostrictive rod in axial vibrations and a piezoelectric cantilever beam in traverse oscillations. The partial differential equations (PDEs) and associated boundary conditions governing the motion of these harvesters are obtained. The eigenvalue problem is then solved for the exact eigenvalues and modeshapes. Furthermore, an exact expression for the steady-sate output power is attained by direct solution of the PDEs. Subsequently, the results are compared to a ROM attained following the Rayleigh-Ritz procedure. It is observed that the eigenvalues and output power near the first resonance frequency are more accurate and has a much faster convergence to the exact solution for the piezoelectric cantilever beam. In addition, it is shown that the convergence is governed by two dimensionless constants, one that is related to the electromechanical coupling and the other to the ratio between the time constant of the mechanical oscillator and the harvesting circuit. Using these results, conclusions are drawn with regards to the design values for which the common single-mode ROM is accurate.

Analysis of Power Generating Performance for Unimorph Cantilever Piezoelectric Beams With Interdigitated Electrodes

2005 ◽  
Author(s):  
Changki Mo ◽  
Sunghwan Kim ◽  
William W. Clark
Keyword(s):  
Low Power ◽  
Cantilever Beam ◽  
Piezoelectric Materials ◽  
Design Parameters ◽  
Interdigitated Electrode ◽  
Power Generators ◽  
Energy Harvesters ◽  
Piezoelectric Cantilever ◽  
Power Harvester ◽  
Unimorph Cantilever

A great amount of research has been done to determine whether piezoelectric materials can be used as power generators for a variety of portable and low power consuming devices. Among the possibilities for energy harvesters, the 31-type cantilever piezoelectric benders have been generally used. In this work a unimorph piezoelectric cantilever beam with the interdigitated electrode pattern was examined. The focus of this paper was to develop a model and propose design parameters to improve the power generating performance of the interdigitated piezoelectric power harvester.

Nonlinear Dynamics of a Special Piezoelectric Energy Harvester With a Special Bistable Piezoelectric Cantilever Beam

2018 ◽  
Author(s):  
Ming Hui Yao ◽  
Wei Xia ◽  
Wei Zhang ◽  
Jian Yu Jiao
Keyword(s):  
Permanent Magnet ◽  
Cantilever Beam ◽  
Piezoelectric Layer ◽  
Magnetic Force ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
High Energy ◽  
Nonlinear Phenomenon ◽  
Piezoelectric Energy ◽  
Piezoelectric Cantilever

This paper presents a special piezoelectric energy harvester system which is obtained by separating the end of the upper piezoelectric layer of the traditional piezoelectric cantilever beam from its basic layer. A mass I is located at the end of the separated upper piezoelectric layer (SUPL), a mass II and a permanent magnet I are located at the end of the separated lower piezoelectric beam (SLPB) and a permanent magnet II is added in the opposite position of the permanent magnet I and they face each other with same polarities. A nonlinear magnetic force which can broaden the frequency bandwidth of the system is generated mutually on the two permanent magnets. Studies find that this special piezoelectric energy harvester has extremely high energy capture efficiency. In order to further explore the reason of high efficiency, experimental research on its dynamic behavior is carried out. The experimental results show that the vibrations of the SUPL and the SLPB are relatively simple. The dynamic behaviors of the SUPL, the SLPB and the unseparated part are different. The unseparated part of the piezoelectric shows relatively complex nonlinear phenomenon due to the interaction of nonlinear magnetic force and the collision. With the increase of the external excitation frequency, period doubling motion and almost periodic motion appear alternately.

scholarly journals Enhancement of the Piezoelectric Cantilever Beam Performance via Vortex-Induced Vibration to Harvest Ocean Wave Energy

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiaozhen Du ◽  
Yan Zhao ◽  
Guilin Liu ◽  
Mi Zhang ◽  
Yu Wang ◽  
...  
Keyword(s):  
Cantilever Beam ◽  
Wave Energy ◽  
High Frequency ◽  
Bluff Body ◽  
Ocean Waves ◽  
Geometrical Parameters ◽  
Outlet Channel ◽  
Electromechanical Transduction ◽  
Air Chamber ◽  
Piezoelectric Cantilever

Renewable and sustainable energies exhibit promising performance while serving as the power supply of a wireless sensor especially located in marine waters. Various microgenerators have been developed to harvest wave energy. However, the conversion ability from a dynamic oscillating source of wave is crucial to enhance their effectiveness in practical applications. In this paper, a new piezoelectric converter system is proposed to harvest the kinetic energy from ocean waves. The vortex-induced effect in an air channel enhances the vibration performance, improving the energy harvesting efficiency. The system comprises an oscillating water column (OWC) air chamber, a bluff body, and a piezoelectric piece for electromechanical transduction. The fluid–solid–electric coupling finite element method was used to investigate the relation between the output voltage and geometrical parameters, including the size and position of the piezoelectric cantilever beam, which is based on the user-defined function of the ANSYS. It is found that the bluff body in the outlet channel above the air chamber induced high-frequency vortex shedding vibration. The regular wave rushed into the air chamber with a frequency of 0.285 Hz and extruded the air across the bluff body in the outlet channel. This incurred the fluctuation of the air pressure and excited the piezoelectric cantilever beam vibration with a high frequency of 233 Hz in the wake region. Furthermore, a continuous electrical output with a peak voltage of 6.11 V is generated, which has potential applications for the wireless sensors on the marine buoy.

The pumping characteristics of screw rotors. I. The theory of calculation of the pumping capacity of screw rotors

1987 ◽  
Vol 52 (2) ◽  
pp. 357-371 ◽  
Author(s):  
František Rieger
Keyword(s):  
Present State ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Screw Rotor ◽  
Screw Rotors

This paper summarizes the present state of the theory of calculation of the pumping capacity of screw rotors. The calculation starts from the equation for the volumetric flow rate of the flow between two unconfined plates modified by correction coefficients obtained from the relationships for the flow rate in simpler geometrical configurations to which the screw rotor may be, under certain circumstances, reduced.

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