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Validation of a CFD model with a triple-lidar system upstream of a wind turbine incomplex terrain
Meyer Forsting, Alexander Raul; Troldborg, Niels; Bechmann, Andreas; Angelou, Nikolas; Vasiljevic,Nikola
Publication date:2016
Document VersionPeer reviewed version
Link back to DTU Orbit
Citation (APA):Meyer Forsting, A. R. (Author), Troldborg, N. (Author), Bechmann, A. (Author), Angelou, N. (Author), &Vasiljevic, N. (Author). (2016). Validation of a CFD model with a triple-lidar system upstream of a wind turbine incomplex terrain. Sound/Visual production (digital)
Validation of a CFD model with a triple-lidarsystem upstream of a wind turbine in complex
terrain
Alexander Meyer Forsting, Niels Troldborg, Andreas Bechmann, Nikolas Angelou,
Nikola Vasiljevic
DTU Wind Energy, Technical University of Denmark
Overview
• The induction zone
• Power curve measurements
• Computational method
• CFD simulations
• Triple-lidar measurements in the induction zone
• CFD – measurement comparison
• Conclusion
• Future work
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DTU Wind Energy, Technical University of Denmark
The induction zone
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Distance from WT
D
Velo
cit
y
DTU Wind Energy, Technical University of Denmark
The induction zone
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Distance from WT
D
Velo
cit
y
Thrust
DTU Wind Energy, Technical University of Denmark
Power curve measurements
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DTU Wind Energy, Technical University of Denmark
Power curve measurements
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Distance from WT
D
Velo
cit
y
2.5 D
DTU Wind Energy, Technical University of Denmark
Power curve measurements
7 15/06/2016
Distance from WT
D
Velo
cit
y
2.5 D 0.5 D
DTU Wind Energy, Technical University of Denmark
Power curve measurements
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D
Velo
cit
y
2.5 D 0.5 D Distance from WT
DTU Wind Energy, Technical University of Denmark
Power curve measurements
9 15/06/2016
D
Velo
cit
y
2.5 D 0.5 D Distance from WT
Induction zone model • Predict uncertainty
• Capture thrust dependency
DTU Wind Energy, Technical University of Denmark
Power curve measurementsin complex terrain
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h
h
DTU Wind Energy, Technical University of Denmark
Power curve measurementsin complex terrain
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h
h
DTU Wind Energy, Technical University of Denmark
Modeling the induction zone in complex terrain
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Wake
Separation
Multi-scale
turbulence
DTU Wind Energy, Technical University of Denmark13 15/06/2016
General
• Multi-purpose finite volume solver
• Block-structured grid with collocated variables
• Highly parallelised
• Body forces are implemented via modified
Rhie-Chow algorithm
Complex terrain
• Steady-state incompressible RANS
• QUICK scheme solved convective terms
• SIMPLE the pressure-linked terms
EllipSys3D
DTU Wind Energy, Technical University of Denmark
Modeling the induction zone in complex terrain
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Multi-scale
turbulence
𝒌 − 𝜺 − 𝒇𝒑 turbulence model
DTU Wind Energy, Technical University of Denmark
Modeling the induction zone in complex terrain
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𝑧0
𝑧
𝑈
DTU Wind Energy, Technical University of Denmark
Modeling the induction zone in complex terrain
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• Neutral stratification
• No Coriolis
Terrain flow becomes Reynolds number independent
DTU Wind Energy, Technical University of Denmark
Modeling the induction zone in complex terrain
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Actuator disc representation of WT
• Permeable disc with body forces
• Intersectional grid determines forces
in fluid domain
• Either constant thrust coefficient over disc
• Or 2-D airfoil data
DTU Wind Energy, Technical University of Denmark
Complex terrain test case: Perdigão
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DTU Wind Energy, Technical University of Denmark
Complex terrain test case: Perdigão
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DTU Wind Energy, Technical University of Denmark
Complex terrain test case: Perdigão
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DTU Wind Energy, Technical University of Denmark
Terrain treatment for mesh generation
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Far-field terrain and reference roughness
• Smoothed over grid spacing and
towards the edges of the domain
DTU Wind Energy, Technical University of Denmark
The domain
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17 km
DTU Wind Energy, Technical University of Denmark
The domain
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DTU Wind Energy, Technical University of Denmark
Grid sensitivity
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Δ𝑥 =𝑅
16= 2.56 𝑚 2.13𝑀 𝑐𝑒𝑙𝑙𝑠
DTU Wind Energy, Technical University of Denmark
Measurements at Perdigão
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• Synchronised lidar measurements around WT and valley
DTU Wind Energy, Technical University of Denmark
Measurements at Perdigão
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Synchronised triple-lidar
DTU Wind Energy, Technical University of Denmark
CFD Results
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21
8°
26
3°
DTU Wind Energy, Technical University of Denmark
CFD Results
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218°
263°
Wind directions
DTU Wind Energy, Technical University of Denmark
Triple-lidar results
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By R. Menke
DTU Wind Energy, Technical University of Denmark
Comparaison triple-lidar and CFD
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1.6 R
2.6 R
DTU Wind Energy, Technical University of Denmark
Comparaison triple-lidar and CFD
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Comparaison triple-lidar and CFD
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Comparaison triple-lidar and CFD
16 m
DTU Wind Energy, Technical University of Denmark
Conclusion
• Automated complex terrain simulations incorporating several pre-
processing steps
• Triple-lidar shows high potential for complex flow measurements
• Large uncertainty in inflow conditions needs to be accounted for
• Steady-state RANS seems to capture induction zone correctly
• Computational uncertainty from:
– Stratification
– Roughness
– Turbine
– Terrain
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DTU Wind Energy, Technical University of Denmark
Future work
• Investigate more measurement periods
• Include variability of wind direction into validation methodology
• Include stratification
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DTU Wind Energy, Technical University of Denmark
Thanks for your attention!
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Questions?