tidal/current energy harvesting using the phenomenon of

1 October 28, 2015

Tidal/current energy harvesting using the phenomenon of Vortex Induced Vibration (VIV) By Andrei Metrikine (homepage.tudelft.nl/v5u5c/)

Tidal/current energy harvesting using the phenomenon of Vortex Induced Vibration (VIV)

2

Content

1.  Main types of current energy converters: uniform motions versus self-excited vibration.

2.  VIVACE system (developed and patented by the University of Michigan)

3.  Von Karman vortex street

4.  The Vortex-Induced Vibration phenomenon

5.  Pros and cons and a way forward.


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Horizontal- and vertical axis turbines

Uniform motion


4

Hydrofoil and tidal kite

Self-excited vibration


5

VIVACE

http://www.vortexhydroenergy.com


6

Von Karman vortex street


7

The origin of VIV studies in offshore engineering


8

Power of VIV: full-scale impression


9

Experiments and countermeasures (when needed)


10

The Strouhal frequency

s

s is the vortex shedding frequency of a stationary cylinder is the diameter of the cylinderis the flow velocity

Stf VD

fDV

=


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The lift and drag coefficients for stationary cylinders

2

2

The lift coefficient: 0.5

The drag coefficient: 0.5

LL

DD

FCDLVFCDLV

ρ

ρ

=

=


12

VIV of an elastically supported cylinder


13

2k

2k

2c

2c

VIV of an elastically supported cylinder


14

Results of the free vibration experiment

( )n nV V Df= ( )n nV V Df=

x max

max

cyl n

y

A X DA Y Df f f

==

=

VIV is a synchronization phenomenon


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The synchronization phenomenon

in-phase synchronization

An original drawing by Christiaan Huygens

illustrating his experiments with pendulum clocks

(17th sentury)

anti-phase synchronization

synchronization with an arbitrary

phase shift

no synchrony

http://www.scholarpedia.org/article/Synchronization


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The forced vibration experiment

Added Mass Added Damping

negative


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The wake oscillator model: idea

!!q + ε (q2 −1) !q + q = A!!y

Equation of Motion of the Structure:

Oscillator:

,A ε Tuning parameters:

Model by Facchinetti et al. (2004)

!!y + 2 ζ Ωn +M St__⎛

⎝⎜⎞⎠⎟

−1

Cx00

⎛

⎝⎜⎜

⎞

⎠⎟⎟!y +Ωn

2 y = M St__⎛

⎝⎜⎞⎠⎟

−2

Cy10 q,


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Generalization to large angles

!!y + 2 ζ Ωn !y + Ωn2 y = M St

__⎛⎝⎜

⎞⎠⎟

−2

− !ySt__

Cx00 + qCy1

0⎛⎝⎜

⎞⎠⎟

1+ St__⎛

⎝⎜⎞⎠⎟

2

!y2 4,

!!q + ε(q2 −1) !q + q = A!!y

!!y + 2 ζ Ωn !y + Ωn2 y = M St

__⎛⎝⎜

⎞⎠⎟

−2

− !ySt__

Cx00 + qCy1

0⎛⎝⎜

⎞⎠⎟

!!q + ε(q2 −1) !q + q = A!!y

Model by Facchinetti et al. (2004)

Model by Ogink & Metrikine (2010)


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Back to VIVACE


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Back to VIVACE

•  The VIVACE converter is a transformational technology.

•  It taps into a vast new source of clean and renewable energy, that of water currents as slow as 1 to 2 m/s, previously off limits to conventional turbine technology.

•  The vast majority of river/ocean currents are slower than 1.5 m/s.


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VIV energy generation: strong point

Occurs in a large range of current velocities and is easily tuneable.


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VIV energy generation: weak point

Currently captures moderate amount of kinetic energy of currents Obvious solution: arrays and use of the wake-induced vibration


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Recent theoretical findings


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Recent theoretical findings

The synchronization range can be expanded and as much as needed kinetic energy can be captured


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Thank you for your attention

tidal/current energy harvesting using the phenomenon of

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