Investigation of the effect of inflow turbulence on vertical axis wind turbine wakes 1 P Chatelain 1 , M Duponcheel 1 , S Zeoli 2 , S Buffin 1 , D-G Caprace 1 , G Winckelmans 1 and L Bricteux 2 1 : Institute of Mechanics, Materials and Civil Engineering (iMMC) Université catholique de Louvain (UCL) 1348 Louvain-la-Neuve, Belgium 2 : Mechanical Engineering Department Université de Mons (UMons) 7000 Mons, Belgium Wake Conference 2017, May 30th - June 1st, 2017
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Investigation of the effect of inflow turbulence on vertical axis wind turbine wakes
1
P Chatelain1, M Duponcheel1, S Zeoli2, S Buffin1, D-G Caprace1, G Winckelmans1 and L Bricteux2
1: Institute of Mechanics, Materials and Civil Engineering (iMMC) Université catholique de Louvain (UCL)
1348 Louvain-la-Neuve, Belgium
2: Mechanical Engineering Department Université de Mons (UMons)
7000 Mons, Belgium
Wake Conference 2017, May 30th - June 1st, 2017
Motivation and outline
• Methodology – The Vortex-Particle Mesh (VPM) method – Turbulent inlet for the VPM method
• Wake physics of a straight-bladed VAWT with turbulent inlet – Wake description – Sensitivity of wake statistics to turbulence properties
• 4 cases : no turbulence and 3 different inflow turbulences
7
x/D
y/D
x/D
x/D
y/D
y/D
ux
/U1
ux
/U1
ux
/U1
TI = 2%, L = D/3, isotropic
TI = 7.5%, L = D/3, isotropic
TI = 7.5%, L = D, anisotropic, Γ = 3.9
Power curve and investigated operating point
8
CP =P
12⇢AU3
� =!R
U
Low resolution runs for whole curve (512 CPUS, 2h)
High resolution runs for present study
TI = 2%, iso, Cp = 0.346
TI = 7.5%, iso, Cp = 0.342
TI = 7.5%, aniso, Cp = 0.357
TI = 0% Cp = 0.339
Coalescing tip vortices
sheetsd�
dt
Recirculation
Volume rendering of k!k
TI = 0%
Volume rendering of k!k
TI = 2% iso
Volume rendering of k!k
TI = 7.5% iso
Volume rendering of k!k
TI = 7.5% aniso
Vorticity magnitude (side view)
TI = 0
TI = 7.5% aniso
TI = 7.5% iso
TI = 2% iso
Vorticity magnitude (top view)
TI = 0
TI = 7.5% aniso
TI = 2% iso
TI = 7.5% iso
Forces and Angle of attack
15
Uwind✓
Angle of attackTypical asymmetry between upstream and downstream parts of a revolution. Oscillations in the downstream part due to the wakes shed upstream
Tangential forceNormal force
TI = 0%
Forces and Angle of attack
16
Uwind✓
With low turbulent, almost no effect on the mean quantities and only small variations around the mean
TI = 2% iso
Angle of attack
Tangential forceNormal force
TI = 0%
Forces and Angle of attack
17
Uwind✓
As the turbulence increases, the envelopes increases but the mean profiles are only slightly affected
TI = 2% iso
TI = 7.5% iso
Angle of attack
Tangential forceNormal force
TI = 0%
Forces and Angle of attack
18
Uwind✓
The envelopes are significantly larger and, in the downstream part of a revolution, the wake signature is no longer present
TI = 2% iso
TI = 7.5% iso
TI = 7.5% aniso
Angle of attack
Tangential forceNormal force
TI = 0%
-1
0
1
y/D
0
0.5
1
u/U
-1
0
1
y/D
-2 0 2 4 6 8 10 12 14 16x/D
0
0.02
0.04
TKE/U
2
Mean wake : horizontal planes
19x/D
Recirculation region where the wake transitions to turbulence
x
y
-2
0
2
y/D
0
0.5
1
u/U
-2
0
2
y/D
-2 0 2 4 6 8 10 12 14 16x/D0
0.01
0.02
0.03
0.04
TKE/U
2
TI = 2% iso
TI = 0%
Faster transition and higher TKE
Recirculation topology modified
-2
0
2
y/D
0
0.5
1
u/U
-2
0
2
y/D
-2 0 2 4 6 8 10 12 14 16x/D0
0.01
0.02
0.03
0.04
TKE/U
2
20x/D
x
y
-2
0
2
y/D
0
0.5
1
u/U
-2
0
2
y/D
-2 0 2 4 6 8 10 12 14 16x/D0
0.01
0.02
0.03
0.04
TKE/U
2
TI = 7.5% iso
TI = 7.5% aniso
No recirculation region, very high TKE and large wake spreading
Faster transition and higer TKE
Mean wake : horizontal planes
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
Mean wake : vertical planes
21
x/D = 1
x/D = 7x/D = 10
x/D = 15
z
y
Uwind
0
0.5
1
u/U
∞
-1 0 1y/D
-1.5
-1
-0.5
0
0.5
1
1.5
z/D
0
0.01
0.02
0.03
0.04
TKE/U
2 ∞
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
TI = 2% iso
TI = 7.5% iso
TI = 7.5% aniso
TI = 0%
Asymmetric wake, most TKE is due to tip vortices
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
Mean wake : vertical planes
22
x/D = 5
x/D = 15
z
y
Uwind
0
0.5
1
u/U
∞
-1 0 1y/D
-1.5
-1
-0.5
0
0.5
1
1.5
z/D
0
0.01
0.02
0.03
0.04
TKE/U
2 ∞
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
TI = 2% iso
TI = 7.5% iso
TI = 7.5% aniso
TI = 0%
Faster decay of the wake due to the turbulence. In the last case, the wake has already much decayed
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
Mean wake : vertical planes
23
x/D = 10
x/D = 15
z
y
Uwind
0
0.5
1
u/U
∞
-1 0 1y/D
-1.5
-1
-0.5
0
0.5
1
1.5
z/D
0
0.01
0.02
0.03
0.04
TKE/U
2 ∞
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
u/U
∞
0
0.5
1
y/D-2 -1 0 1 2
z/D
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
TKE/U
2 ∞
0
0.01
0.02
0.03
0.04
TI = 2% iso
TI = 7.5% iso
TI = 7.5% aniso
TI = 0%
The asymmetry persists for long distances but is reduced with increased turbulence levels
0 50 100 150 200 250 300 350x
-20
-15
-10
-5
0
5
10
15
20
y
Comparison of the two turbulent inflow methods
24
3-D Mann Precursor
Time-correlated 2-D planesThe methods give similar results even though the 3-D precursor gives higher TKE in the wake but a smaller variation of AoA
✓
↵
-2
0
2
x2
0 5 10 15y2
0.02
0.04
z2
-2
0
2
x2
0 5 10 15y2
0.02
0.04
z2
3-D Mann Precursor
Time-correlated 2-D planes✓
x/D
y/D
TKE/U21
y/D
Conclusions
• Application of Vortex Particle-Mesh method to the investigation of VAWT wakes with various inflow turbulence (different intensities and structures)
• Complex wake topology and dynamics due to unsteady loading of the blades - Asymmetric wake, presence of streamwise corner vortices
and a recirculation region
• Inflow turbulence accelerates the development of the instabilities of tip vortex interactions, leading to an accelerated wake decay
• The strong anisotropic case shows large scale wake meandering and the recirculation region is no longer present
• Comparison with HAWT wakes25
Wakes: upcoming projects
• Learning and collective intelligence for optimized operations in wake flows
• Reproduction of bird flying gaits and self-organization into formations
26
ERC Consolidator GrantWake Op Collhttps://sites.uclouvain.be/wakeopcoll2017-2022
Concerted Research Action RevealFlighthttps://sites.uclouvain.be/revealflight2017-2022
27
Acknowledgments
The PPM (Parallel Particle Mesh) library
Simulations performed on the Cenaero - CECI Tier-1 Infrastructure funded by the Walloon Region, Grant No. 1117545
UCL CISM - Institut de Calcul Intensif et de Stockage de Masse CECI - Consortium des Equipements de Calcul Intensif