Harvesting Energy by Flow Included Motions

Bernitsas, Michael M.

doi:10.1007/978-3-319-16649-0_47

Cited by 34 publications

(13 citation statements)

References 72 publications

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“…The greater the Reynolds number, the greater the pressure difference between the upper and lower surfaces, and the greater the lift force on the cylinder. This regularity is consistent with the previous research results [19,21]. Meanwhile, for the rear of the cylinder, due to the influence of shedding vortices, the distribution of the pressure coefficients became somewhat disorderly.…”

Section: (B) Flow-induced Vibrationsupporting

confidence: 92%

“…As for the Re range, in the present study, the Re range was from 3 × 10 4 to 7 × 10 4 , which belonged to the initial and VIV stage. The PTC could trigger galloping, which corresponded to the Re range of 10 × 10 4 to 13 × 10 4 , and the phenomenon has been widely researched [7][8][9][10][11][12][14][15][16][19][20][21]. In the present simulation with the free surface flow, if the incoming flow velocity was high in the galloping range, the amplitude response of the oscillator was big enough to reach the free surface, which interrupted the calculation.…”

Section: Amplitude and Frequencymentioning

confidence: 79%

“…The transient, viscous fluid solutions were obtained using a numerical approximation of the incompressible 2D-URANS equations with the one-equation Spalart-Allmaras turbulence model. The mathematical formulations can be described as follows [21]:…”

Section: Mathematical Modelmentioning

confidence: 99%

“…where υ is the intermediate working variable of the turbulence model that obeys the following transport equation [21]:…”

Section: Of 19mentioning

confidence: 99%

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Vortex-Induced Vibration Characteristics of a PTC Cylinder with a Free Surface Effect

et al. 2020

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The experimental study of vortex induced vibration needs to be carried out in water tunnel, but in previous associated simulation work, the water tunnel was treated as an infinite flow field in the depth direction with the effect of the free surface neglected. In the paper, the dynamic characteristics and physical mechanisms of a passive turbulence control (PTC) cylinder in a flow field with a free surface is studied, and the combined technique of a volume of fluid (VOF) method and vortex-induced vibration (VIV) was realized. In the range of Reynolds number studied in this paper (3.5 × 104 ≤ Re ≤ 7.0 × 104), the dynamic parameters (lift and drag coefficients), vortex structures, VIV response (amplitude and frequency ratios), and energy harvesting characteristics of a PTC cylinder under different flow conditions were obtained. The study found that: (1) the shear layer was made more unstable behind the cylinder by the free surface, which made it quicker to reach periodic stability, and the asymmetry shortened the initial stage of vibration of the oscillator, which made it easier to produce dynamic control of the motion of the oscillator; (2) the presence of the free surface only affected the positive amplitude ratio, but had almost no effect on the negative amplitude ratio; (3) the frequency ratio in the free surface flow was closer to the experimental data; (4) the presence of the free surface did not affect the detached vortex pattern in the flow around the stationary cylinder, but in the VIV, the lower the free surface height Z, the more vortices that were shed from the moving cylinder.

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Section: (B) Flow-induced Vibrationsupporting

confidence: 92%

Section: Amplitude and Frequencymentioning

confidence: 79%

Section: Mathematical Modelmentioning

confidence: 99%

“…where υ is the intermediate working variable of the turbulence model that obeys the following transport equation [21]:…”

Section: Of 19mentioning

confidence: 99%

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Vortex-Induced Vibration Characteristics of a PTC Cylinder with a Free Surface Effect

et al. 2020

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“…The latter can be controlled converting Marine Hydrokinetic (MHK) energy to mechanical and electrical energy. VIV and galloping are the most commonly occurring FIM and are implemented in the VIVACE Converter mechanics along with interaction phenomena between shear layers and wakes of upstream cylinders (Bernitsas et al 2011(Bernitsas et al , 2016). An important question in the Fluid-Structure Interaction (FSI) mechanics of this ALT converter is how close cylinders can be placed to achieve highest hydrokinetic energy conversion.…”

Section: Introductionmentioning

confidence: 99%

Hydrokinetic energy conversion by two rough tandem-cylinders in flow induced motions: Effect of spacing and stiffness

Sun

Kim

et al. 2017

Renewable Energy

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Flow Induced Motions (FIMs) of rigid circular cylinders, and particularly VIV (Vortex Induced Vibrations) and galloping, are induced by alternating lift. The VIVACE (VIV for Aquatic Clean Energy) Converter uses single or multiple cylinders, in tandem, on elastic end-supports, in synergistic FIM, to convert MHK energy to electricity. Selectively distributed surface roughness is applied to enhance FIM and increase efficiency. In this paper, two cylinders are used in tandem with center-to-center spacing of 1.57, 2.0 and 2.57 diameters, harnessing damping ratio 0.00< <0.24, for Reynolds number 30,000 Re 120,000. The virtual spring-damping system V ck in the Marine Renewable Energy Laboratory (MRELab) enables embedded computer-controlled change of viscous-damping and spring-stiffness for fast and mathematically correct oscillator realization, without including the hydrodynamic force in the closed control loop. Experimental results for oscillatory response, energy harvesting, and efficiency are presented and the envelope of optimal power is derived. All the experiments were conducted in the Low Turbulence Free Surface Water (LTFSW) Channel of the MRELab of the University of Michigan. The main conclusions are: (1) For the tested cylinder spacing, two cylinders harness power is between 2.56 and 13.49 times the power of a single cylinder, the efficiency of two cylinders is between 2.0 and 6.68 of a single cylinder. (2) The MHK power harnessed by the upstream cylinder is increased by up to 100%, affected by the downstream cylinder. (3) The MHK power harnessed by the downstream cylinder and its FIM are affected to a lesser extent by the interaction. (4) VIVACE can harness energy from flows as slow as 0.4m/s with no upper limit in flow velocity. (5) Close spacing and high spring stiffness yield highest harnessed power. (6) The optimal harnessed power shifts to softer springs as spacing increases.

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Hydrokinetic Energy Conversion Using a Single-Cylinder Nonlinear Oscillator in Flow Induced Oscillations

Bernitsas

Sun

2021

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Harvesting Energy by Flow Included Motions

Cited by 34 publications

References 72 publications

Vortex-Induced Vibration Characteristics of a PTC Cylinder with a Free Surface Effect

Vortex-Induced Vibration Characteristics of a PTC Cylinder with a Free Surface Effect

Hydrokinetic energy conversion by two rough tandem-cylinders in flow induced motions: Effect of spacing and stiffness

Hydrokinetic Energy Conversion Using a Single-Cylinder Nonlinear Oscillator in Flow Induced Oscillations

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