Fluidic energy harvesting beams in grid turbulence

Danesh-Yazdi, Amir H.; Goushcha, Oleg; Elvin, Niell; Andreopoulos, Yiannis

doi:10.1007/s00348-015-2027-2

Cited by 20 publications

(15 citation statements)

References 22 publications

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“…In contrast to the previously discussed turbulence intensity, the mean inflow velocity has a significant influence on k , even in the passive mode. A higher mean velocity in the test section ( U ref ) always corresponds to higher values of k , as already observed, e.g., in the experiments by Kurian and Fransson (2009) and Danesh-Yazdi et al. (2015).…”

Section: Resultssupporting

confidence: 83%

A novel type of semi-active jet turbulence grid

Szaszák

Roloff

Bordás

et al. 2018

Heliyon

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This article describes a novel approach to generate increased turbulence levels in an incoming flow. It relies on a cost-effective and robust semi-active jet grid, equipped with flexible tubes as moving elements attached onto tube connections placed at the intersections of a fixed, regular grid. For the present study, these flexible tubes are oriented in counter-flow direction in a wind tunnel. Tube motion is governed by multiple interactions between the main flow and the jets exiting the tubes, resulting in chaotic velocity fluctuations and high turbulence intensities in the test section. After describing the structure of the turbulence generator, the turbulent properties of the airflow downstream of the grid in both passive and active modes are measured by hot-wire anemometry and compared with one another. When activating the turbulence generator, turbulence intensity, turbulent kinetic energy, and the Taylor Reynolds number are noticeably increased in comparison with the passive mode (corresponding to simple grid turbulence). Furthermore, the inertial subrange of the turbulent energy spectrum becomes wider and closely follows Kolmogorov's -5/3 law. These results show that the semi-active grid, in contrast to passive systems, is capable of producing high turbulence levels, even at low incoming flow velocity. Compared to alternatives based on actuators driven by servo-motors, the production and operation costs of the semi-active grid are very moderate and its robustness is much higher.

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Section: Resultssupporting

confidence: 83%

A novel type of semi-active jet turbulence grid

Szaszák

Roloff

Bordás

et al. 2018

Heliyon

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“…The power decay of with x/L r is similar in form to the energy decay in isotropic homogeneous turbulence, , where and M are the turbulent kinetic energy and the characteristic length in the isotropic homogeneous turbulence, respectively, where the exponent β representing the decay rate is in the range of β = −1.4 ~ −1.2 in general (Krogstad & Davidson 2011; Danesh-Yazdi et al. 2015). It should be kept in mind that even if the vortices have broken and gradually decay for x/L r > 2 in the present experiment, vortices interactions are still sustained in the wake, meaning that the wake is recovering and has not reached the fully developed turbulence.…”

Section: Experimental Results and Analysesmentioning

confidence: 93%

Fluid–structure–sound interaction in noise reduction of a circular cylinder with flexible splitter plate

Fan

Wang

2021

J. Fluid Mech.

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“…We theoretically derived and experimentally validated an estimate of the forcing function due to grid-generated turbulence acting on a short and relatively stiff piezoelectric energy harvester in Danesh-Yazdi et al (2015)…”

Section: Governing Electromechanical Equations With Turbulence Forcing Model: a Theoretical Frameworkmentioning

confidence: 99%

“…The semi-passive grid, shown in Figure 4(b), is a novel design in which ping-pong balls are attached to the nodes of a passive grid to enhance turbulence generation. Detailed properties and dimensions of the two grids are given in Danesh-Yazdi et al (2015).…”

Section: Experimental Setup and Techniquesmentioning

confidence: 99%

“…Also, Hobeck and Inman (2010) analytically and experimentally studied the behavior of harvesting arrays, referred to as “artificial piezoelectric grass”, in the wake of a block mounted on a wind tunnel wall. More recently, however, we (Danesh-Yazdi et al, 2015) studied the performance of piezoelectric cantilever beams in flows where the turbulence is generated by passive, semi-passive and active grids. We found that the average power harvested by the beams displayed a power-law behavior with respect to the distance from the grid.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Parametric analysis of fluidic energy harvesters in grid turbulence

Danesh-Yazdi¹,

Elvin

Andreopoulos

2016

Journal of Intelligent Material Systems and Structures

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Even though it is omnipresent in nature, there has not been much research in the literature involving turbulence as an energy source for piezoelectric fluidic harvesters. In the present work, a grid-generated turbulence forcing function model which we derived previously is employed in the single degree-of-freedom electromechanical equations to find the power output and tip displacement of piezoelectric cantilever beams. Additionally, we utilize simplified, deterministic models of the turbulence forcing function to obtain closed-form expressions for the power output. These theoretical models are studied using experiments that involve separately placing a hot-wire anemometer probe and a short PVDF beam in flows where turbulence is generated by means of passive and semi-passive grids. From a parametric study of the deterministic models, we show that a white noise forcing function best mimics the experimental data. Furthermore, our parametric study of the response spectrum of a generic fluidic harvester in grid-generated turbulent flow shows that optimum power output is attained for beams placed closer to the grid with a low natural frequency and damping ratio and a large electromechanical coupling coefficient.

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Fluidic energy harvesting beams in grid turbulence

Cited by 20 publications

References 22 publications

A novel type of semi-active jet turbulence grid

A novel type of semi-active jet turbulence grid

Fluid–structure–sound interaction in noise reduction of a circular cylinder with flexible splitter plate

Parametric analysis of fluidic energy harvesters in grid turbulence

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