Small-Scale Wind Energy Harvesting From Flow-Induced Vibrations

2011 ◽  
Author(s):  
Vishak Sivadas ◽  
Adam M. Wickenheiser
Keyword(s):  
Energy Harvesting ◽  
Wind Energy ◽  
Boundary Layers ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Environmental Parameters ◽  
Small Scale ◽  
Low Speed ◽  
Structural Deformations ◽  
Flow Induced Vibrations

Significant wind energy exists in the boundary layers around naturally occurring and manmade structures. This energy source has remained largely untapped, even though it presents a significant source of energy for powering wireless devices in built-up areas. This paper discusses a study on harnessing energy from piezoelectric transducers by using bluff body and vortex-induced vibration phenomena induced by low-speed flows. The proposed devices are miniature, scalable, aeroelastic wind harvesters designed for extracting turbulent, low-speed wind energy from the boundary layers around structures. The design configuration consists of a bluff body with a flexible piezoelectric cantilever attached to the trailing edge. In this design, transverse vibrations are induced in the piezoelectric members by alternating vortex shedding. The multi-physics software package COMSOL is used for coupled simulation of the fluid and structural domains, and Matlab is used to couple the structural deformations to the attached power harvesting circuitry. The design and environmental parameters are varied to optimize the configuration and to identify the significant parameters in the design. The lock-in phenomenon, in which the vortex shedding frequency is entrained to the fundamental structural frequency, is exploited to achieve resonance over a range of flow velocities, thus increasing the velocity “bandwidth” of the devices. Simulations are run for different characteristic dimensions or shapes for the bluff body to study the strength and nature of vortex shedding in the presence of vibrating beam sections. The results of parameter variation for the design configuration is presented and discussed with regard to broadband wind energy harvesting.

Enhancement of low-speed piezoelectric wind energy harvesting by bluff body shapes: Spindle-like and butterfly-like cross-sections

2020 ◽  
Vol 103 ◽  
pp. 105898
Author(s):  
Junlei Wang ◽  
Chengyun Zhang ◽  
Shanghao Gu ◽  
Kai Yang ◽  
Hang Li ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Wind Energy ◽  
Cross Sections ◽  
Bluff Body ◽  
Low Speed ◽  
Body Shapes

Coherent structures in oscillatory boundary layers

2003 ◽  
Vol 474 ◽  
pp. 1-33 ◽  
Author(s):  
PAOLA COSTAMAGNA ◽  
GIOVANNA VITTORI ◽  
PAOLO BLONDEAUX
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Vortex Structures ◽  
Small Scale ◽  
Computational Domain ◽  
Steady Flows ◽  
Low Speed ◽  
Sequence Of Events ◽  
Low Speed Streaks ◽  
Oscillatory Boundary Layers

The dynamics of the vortex structures appearing in an oscillatory boundary layer (Stokes boundary layer), when the flow departs from the laminar regime, is investigated by means of flow visualizations and a quantitative analysis of the velocity and vorticity fields. The data are obtained by means of direct numerical simulations of the Navier–Stokes and continuity equations. The wall is flat but characterized by small imperfections. The analysis is aimed at identifying points in common and differences between wall turbulence in unsteady flows and the well-investigated turbulence structure in the steady case. As in Jimenez & Moin (1991), the goal is to isolate the basic flow unit and to study its morphology and dynamics. Therefore, the computational domain is kept as small as possible.The elementary process which maintains turbulence in oscillatory boundary layers is found to be similar to that of steady flows. Indeed, when turbulence is generated, a sequence of events similar to those observed in steady boundary layers is observed. However, these events do not occur randomly in time but with a repetition time scale which is about half the period of fluid oscillations. At the end of the accelerating phases of the cycle, low-speed streaks appear close to the wall. During the early part of the decelerating phases the strength of the low-speed streaks grows. Then the streaks twist, oscillate and eventually break, originating small-scale vortices. Far from the wall, the analysis of the vorticity field has revealed the existence of a sequence of streamwise vortices of alternating circulation pumping low-speed fluid far from the wall as suggested by Sendstad & Moin (1992) for steady flows. The vortex structures observed far from the wall disappear when too small a computational domain is used, even though turbulence is self-sustaining. The present results suggest that the streak instability mechanism is the dominant mechanism generating and maintaining turbulence; no evidence of the well-known parent vortex structures spawning offspring vortices is found. Although wall imperfections are necessary to trigger transition to turbulence, the characteristics of the coherent vortex structures, for example the spacing of the low-speed streaks, are found to be independent of wall imperfections.

Y-type three-blade bluff body for wind energy harvesting

2018 ◽  
Vol 112 (23) ◽  
pp. 233903 ◽  
Author(s):  
Feng-Rui Liu ◽  
Hong-Xiang Zou ◽  
Wen-Ming Zhang ◽  
Zhi-Ke Peng ◽  
Guang Meng
Keyword(s):  
Energy Harvesting ◽  
Wind Energy ◽  
Bluff Body

scholarly journals The State-of-the-Art Brief Review on Piezoelectric Energy Harvesting from Flow-Induced Vibration

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Hongjun Zhu ◽  
Tao Tang ◽  
Huohai Yang ◽  
Junlei Wang ◽  
Jinze Song ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Bluff Body ◽  
Mechanical Energy ◽  
Wake Flow ◽  
Structural Vibration ◽  
Small Scale ◽  
Flow Induced Vibration ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Self Powered

Flow-induced vibration (FIV) is concerned in a broad range of engineering applications due to its resultant fatigue damage to structures. Nevertheless, such fluid-structure coupling process continuously extracts the kinetic energy from ambient fluid flow, presenting the conversion potential from the mechanical energy to electricity. As the air and water flows are widely encountered in nature, piezoelectric energy harvesters show the advantages in small-scale utilization and self-powered instruments. This paper briefly reviewed the way of energy collection by piezoelectric energy harvesters and the various measures proposed in the literature, which enhance the structural vibration response and hence improve the energy harvesting efficiency. Methods such as irregularity and alteration of cross-section of bluff body, utilization of wake flow and interference, modification and rearrangement of cantilever beams, and introduction of magnetic force are discussed. Finally, some open questions and suggestions are proposed for the future investigation of such renewable energy harvesting mode.

scholarly journals Urban Wind Harvesting Using Flow-Induced Vibrations

2020 ◽  
Vol 16 (4) ◽  
pp. 71-79
Author(s):  
Levon Ghabuzyan ◽  
Christopher Luengas ◽  
Jim Kuo
Keyword(s):  
Wind Tunnel ◽  
Energy Harvesting ◽  
Wind Energy ◽  
Wind Turbine ◽  
Cantilever Beam ◽  
Wind Turbines ◽  
Wind Farms ◽  
Urban Environments ◽  
The Body ◽  
Flow Induced Vibrations

The growing global interest in sustainable energy has paved the way to the rapid development of large-scale wind farms, consisting of dozens to hundreds of wind turbines. Although these large wind farms can generate enormous amount of power, they are also costly and require large areas of land or water, and thus are not suitable for urban environments. Smaller urban wind turbines have been developed for urban environments, but there are significant challenges to their widespread deployment. One of these challenges are their urban wind flows as they are strongly affected by complex building structures, producing highly turbulent flows. Any urban wind turbine would need to be designed to function efficiently and safely under these flow conditions; however, these unpredictable and turbulent winds can induce undesirable vibrations and cause early failures. Recently, bladeless wind turbines are gaining interest due to their reduced costs compared with conventional wind turbines such as the vertical-axis wind turbine and horizontal-axis wind turbine. These bladeless turbines convert flow wind energy into vibration energy, then converts the vibration energy into electricity. This paper examines the effects of force-induced vibrations on a cantilever beam system through wind tunnel experimentation. When fluid flows around a bluff body, periodic shedding of vortices may occur under the right conditions. The vortex shedding process creates an asymmetric pressure distribution on the body which causes the body to oscillate, known as vortex-induced vibrations. The purpose of the paper is to understand the factors affecting flow-induced vibrations and to improve wind energy harvesting from these vibrations. The first part of the paper focuses on wind tunnel experiments, by utilizing a cantilever beam configuration, conceptualized by previous research. Then, the experimental model was tested in different configurations, to determine the best setup for maximizing vibrations induced on the model. The long-term goal of the project was utilizing the model to optimize the system to improve efficiency of wind energy harvesting. The experimental results showed that the presence of an upstream cylinder will significantly improve the amplitude of vibration for energy harvesting, furthermore, the experiments showed that spacing in different directions also affect the amplitude of the vibrations. A two tandem cylinder system was used in this work, including a fixed rigid upstream cylinder and a downstream cylinder supported by a cantilever beam. Various configurations of these two cylinders in terms of spanwise and streamwise separation distances were studied and their maximum and root mean square displacements are reported for different wind speeds. Results showed that the presence of an upstream cylinder will significantly improve the amplitude of vibrations. This work verified that a wind energy harvester needs to consider the effects of wind speed and separation configuration of the cylinders in order to maximize the harvester’s performance in urban environments. KEYWORDS: Sustainable Energy; Energy Harvesting; Urban Environments; Bladeless Wind Turbines; Flow-Induced Vibrations; Cantilever Beam System; Wind Tunnel; Wake

scholarly journals An Ultra-Durable Windmill-Like Hybrid Nanogenerator for Steady and Efficient Harvesting of Low-Speed Wind Energy

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Ying Zhang ◽  
Qixuan Zeng ◽  
Yan Wu ◽  
Jun Wu ◽  
Songlei Yuan ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Wind Energy ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Low Speed ◽  
Hybrid Nanogenerator ◽  
Device Structures ◽  
Improved Performance ◽  
Triboelectric Nanogenerators ◽  
Output Characteristics

AbstractWind energy is one of the most promising and renewable energy sources; however, owing to the limitations of device structures, collecting low-speed wind energy by triboelectric nanogenerators (TENGs) is still a huge challenge. To solve this problem, an ultra-durable and highly efficient windmill-like hybrid nanogenerator (W-HNG) is developed. Herein, the W-HNG composes coupled TENG and electromagnetic generator (EMG) and adopts a rotational contact-separation mode. This unique design efficiently avoids the wear of friction materials and ensures a prolonged service life. Moreover, the generator group is separated from the wind-driven part, which successfully prevents rotation resistance induced by the friction between rotor and stator in the conventional structures, and realizes low-speed wind energy harvesting. Additionally, the output characteristics of TENG can be complementary to the different performance advantages of EMG to achieve a satisfactory power production. The device is successfully driven when the wind speed is 1.8 m s−1, and the output power of TENG and EMG can achieve 0.95 and 3.7 mW, respectively. After power management, the W-HNG has been successfully applied as a power source for electronic devices. This work provides a simple, reliable, and durable device for improved performance toward large-scale low-speed breeze energy harvesting.

Sign in / Sign up

Export Citation Format

Share Document