wind & marine energies

Topic 3 Wind & Marine Energies

French proposals:

ECN/LHEEA

UGA/LEGI

CNRS – NTU French-Singapourean Network on Renewable Energy 4-9 July Porticcio

1

Wind and Marine Energies

• Onshore & Offshore Wind

• Wave Energy

• Tidal Energy

• Ocean Thermal Energy (OTEC)

• Salinity Gradients

• Biofuels

• . . .

The activity within the network will primarily focus on

Tidal and Wind Energy

- Strong interest both for France and Singapore

- Will allow an easy start of networking activities

Coordinators:

Pierre Ferrant (LHEEA Lab., Ecole Centrale de Nantes)

Narasimalu Srikanth (ERI@N/NTU)

• Subtopic 1: Tidal Energy

Coordinators: David Le Touzé (LHEEA, ECN)


• Wave and current conditions in the coastal zone

• Influence of unsteady conditions on energy production

• Wave effects, interactions between turbines

• Subtopic 2: Wind Energy Coordinators: Isabelle Calmet (LHEEA, ECN)


• Ressource assessment in remote coastal locations

• Low flow tropical wind turbine in shallow waters

Content

Extension of the HOS nonlinear deterministic wave model to

variable bathymetry (ECN-LHEEA)

Tidal Energy : Wave and current conditions in the coastal zone

(Quick) Review of deterministic numerical models for nonlinear water waves

CPU time is key for application to large time & space scale problems: 0(10-100 km2) for several hours of simulation

• Standard BEM : 0(N2) computing time • FEM : O(N2) • Optimized FEM: O (NlogN) • Accelerated BEM (preFFT or FMA): 0(NLogN)

• Full Finite Difference O(N2) (or better with multigrid) ex: OceanWave3D (Bingham et al) • Harmonic Polynomial Cell method (Zhao & Faltinsen) O(N2)

• Higher Order Spectral (HOS) method : O(NLogN) Proved to be 4-10 times faster than one of the best finite difference solver (OceanWave3D) for water wave propagation problems See: G. Ducrozet, H.B. Bingham, A.P. Engsig-Karup, F. Bonnefoy, P. Ferrant : A Comparative Study of Two Fast Nonlinear Free Surface Water Wave Models, Int. Journal for Numerical Methods in Fluids 69 (11), 1818-1834, 2012.

5

State of the art Higher Order Spectral (HOS) models

Directional sea state evolution over a large domain (>105km2) with detection of freak waves Ducrozet , Bonnefoy, Le Touzé, Ferrant Natural Hazards & Earth Systems Science, Vol.7, 109-122, 2007 (59 citations) Both versions available as Open-source codes: https://github.com/LHEEA/HOS-ocean/wiki https://github.com/LHEEA/HOS-NWT/wiki

North Atlantic spectrum Tp=12.5s, Hs=10.8m, lp=244m

6

https://github.com/LHEEA/HOS-ocean/wiki




https://github.com/LHEEA/HOS-NWT/wiki




Tidal Energy :Wave and current conditions in the coastal zone

ECN-LHEEA: Extension of the HOS scheme to variable bathymetry

Validations: immersed 2D barrier , Harmonic analysis

Validations: Scripps/La Jolla Canyon (California) Case treated in Gerostathis et al (2008) :

Regular wave T=15s, H=1m (λ=351m)

Next step: Wave-current interactions in coastal zones

Extension of the HOS scheme to variable bathymetry

HOS model :

𝑀 = 1 ; 𝑀𝑏 = 7 ; ℎ𝑚𝑖𝑛 = 30m Coupled-mode model Gerostathis et al.

Linear theory - 3 modes

1

ECN-LHEEA : Development of a Cartesian grid, weakly

compressible finite volumes Navier-Stokes solver with

applications to marine structures (WCCH solver)

o Automatic Mesh Refinement

o Explicit time integration

o Higher order (4th order)

o Highly scalable (HPC oriented)

Tidal Energy : Wake effects, interactions between turbines

Tidal Energy : Wake effects, interactions between turbines

Prediction of the time depending energy harvesting depending on the farm arrangement • Global efficiency of the farm • Individual turbines production

ECN-LHEEA/ALSTOM: Coupling the WCCH solver with simplified models for the turbines (actuator disc or actuator lines)

Accounting for environmental conditions - Realistic turbulent incoming flow - Bathymetry

Mini-farm simulation over a bathymetry

actuator-disc actuator-line

To be compared with NTU model ?

11

../../../Documents/DiaporamasCongrès/Videos and Pictures LHEEA/Videos EWTEC/EXPO ORCA 3.mp4

CFD developments on tidal turbine modelling

at UGA-LEGI

Tidal Energy : Influence of unsteady inflow conditions on energy production

HydroQuest (www.hydroquest.net) manufactures and markets

hydrokinetic river and tidal turbines.

• High fidelity unsteady simulations (LES)

of hydrokinetic turbine

to better understand turbine performance

- 3 tip speed ratios studied: 𝜆 = Ω𝑅

𝑉0

LEGI : 1) Performance of hydrokinetic turbine

N. Guillaud, G. Balarac and E. Goncalves (Pprime)

• Performance measurement:

Power coefficient as a function of the

angular position

• λ = 2 • λ = 1 • λ = 2.5

– LES - - Expe

Power coefficient: 𝐶 𝑝 = 𝐶𝑝 𝑂𝑀 𝑑𝑆

𝐶𝑝 𝑂𝑀 =𝜆𝑂𝑀∧ 𝑃𝑛−𝜏 .𝑛 .𝑒𝑧

0.5𝜌𝐷𝑅𝐻𝑉02 with

λ = 2 λ = 1


• λ = 2 • λ = 1 • λ = 2.5 – LES - - Expe

(a) Contours of

𝐶𝑝 𝑂𝑀

(b) Q criterion

(coherent vortices)

colored by axial

vorticity

Power coefficient as a function of the

angular position

Dynamic stall effect

decreases the performance

Blade/arm connection

decreases the performance


λ = 2

λ = 1 λ = 2.5

LEGI : 2) A BEM-RANS approach for prediction of ducted hydrokinetic turbines

• Equations to be solved :

• Source term S locally active in each cell of the virtual

rotor surface :

N = number of rotor blades R = rotor radius wr = blade width

• BEM-RANS methodology :

rotor blades suppressed and replaced with cells

discretizing the surface swept by the actual

rotor blades over a period of rotation

F. Dominguez, J.-L. Achard and C. Corre (LMFA)

16

Fast parametric study of blockage ratio and lateral distance effects using BEM-RANS

• Model exploitation : multiple-turbine row in a channel

Computed velocity field for a 15-turbine row

Averaged power coefficient

LEGI : 2) A BEM-RANS approach for prediction of ducted hydrokinetic turbines

1 set of turbines

17

Simulation of Atmospheric Flows in Urban and Coastal

Areas (LHEEA-ECN)

Wind Energy : Ressource assessment in remote coastal locations


ECN-LHEEA: Local high resolution simulation of wind condition in a coastal area (Quiberon Bay, Brittany) Multiple embedded computational domains Could be used in complement to large scale NTU simulations ?

Simulation of Wind/Wave interactions (LHEEA-ECN)



ECN-LHEEA:

Wave/Atmospheric flow interactions: Influence of waves on wind resource/profile LES Atmospheric code (P. Sullivan, NCAR) Coupled with HOS code for waves (LHEEA) PhD in progress Work open to benchmarking

Wave drag on wind

Wave thrust on wind

Wave drag on wind

1) HOS-LES simulations for different wave ages

The wind profile does not satisfy the log law (Monin-Obukhov theory), especially

at high wave ages (low-level jet (1))

22/22

Wave age 1.6 (case 1) Wave age 15 (case 2) Wave age 60 (case 3)

(1) Kudryavtsev et Makin, Impact of Swell on the Marine Atmospheric Boundary Layer. Journal of Physical Oceanography, 2003

• Wind Energy : Low flow tropical wind turbine in shallow waters

Development of an Innovative Floating Wind Turbine

Concept (UGA-LEGI)

3) OWLWIND project: floating wind turbine

Vertical Axis Wind Turbine (VAWT) can have various advantages: • Stability • Reduction of floating platform • Better robustness • Easier maintenance

But, classic VAWT are known to be less efficient than Horizontal Axis Wind Turbine (HAWT)

OWLWIND project : • Design a new runner to propose an efficient VAWT

• Step 1: performance measurement in wind tunnel

S. Barre, J.-L. Achard, G. Maurice and G. Balarac

24

3) OWLWIND project: floating wind turbine

+50%

Tip speed ratio

Pow

er c

oef

fciie

nt

classic VAWT

OWLWIND concept

0,2

0,25

0,3

0,35

0,4

0,45

0,5

0,55

0 200000 400000 600000 800000 1000000

OWLWIND

SANDIA

H 2 blades

HAWT +8% +17%

+50%

Reyp

Pow

er c

oef

fciie

nt

OWLWIND SANDIA

H HAWT

Results of the 1st step : • Power coefficient strongly improved

at the best operating point

• Extrapolation at real Reynolds number value shows very good performance

25

• Wind Energy : Low flow tropical wind turbine in shallow waters

Numerical and Experimental modelling of Offshore Wind

Turbines (LHEEA-ECN)

Wind generating system

> Wind generation

• Development and Validation of the system for the wave tank

• Offshore wind spectrum ( blower control)

• Methodology for offshore floating wind turbine testing

Low turbulence wind generation (<4%)

& homogeneous flow

27

Seakeeping of offshore wind turbine

• Aero-hydroelastic coupling in offshore floating wind turbine • System based approach : coupling FAST/Aquaplus

(PhD M. Philippe, 2012)

• Experimental test (NREL 5MW, dutch trifloater,scale 1/50) (PhD A. Courbois, 2013)

M. Philippe, A. Babarit, P. Ferrant (2012) Modes of response of an offshore wind turbine with directional

wind and waves. Renewable Energy, Vol. 49, pp. 151-155

Pitch a

ngle

Wave direction 0 deg





28

../../../Documents/DiaporamasCongrès/Videos and Pictures LHEEA/Videos EWTEC/EXPO Osaka V3.mp4

Seakeeping of Vertical Axis Wind Turbines

• PhD Vincent LEROY (in progress):

29

0

2

4

6

8

10

12

14

16

18

20

6,00 8,00 10,00 12,00

Ts (s)

Hs(m

)

CFD

essais

0,00E+00

2,00E+06

4,00E+06

6,00E+06

8,00E+06

1,00E+07

1,20E+07

1,40E+07

1,60E+07

1,80E+07

2,00E+07

6 7 8 9 10 11 12Ts (s)

Fx (

N)

CFD Essais

0,00E+00

2,00E+07

4,00E+07

6,00E+07

8,00E+07

1,00E+08

1,20E+08

1,40E+08

1,60E+08

1,80E+08

6 7 8 9 10 11 12Ts (s)

My (

Nm

)

CFD Essais

> Experimental study wind turbine fundation

• Tests in wave tank in intermediate water

• Monopile and jacket

• Extreme loading (Global loading)

> Future research activities :

• structural similarity (1st mode)

Collaboration U. Osaka –K. Iijima

• Coupling SWENSE with structural solver

• Extreme conditions estimate

• Fatigue analysis

SEMREV test site (LHEEA-ECN)

31

SEMREV test site (LHEEA-ECN)

32

• Subtopic 1: Tidal Energy

• Wave and current conditions in the coastal zone

• Influence of unsteady conditions on energy production

• Wave effects, interactions between turbines

• Subtopic 2: Wind Energy

• Ressource assessment in remote coastal locations

• Low flow tropical wind turbine in shallow waters

Summary