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1. Numerical Investigation of Distributed Trailing Edge
Suction for Wind Turbine Aerofoils using CFD
Vinit V. Dighe
The University of Auckland
Supervisor: Dr. John E. Cater
13th February 2015
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2. Overview
1 Challenges for large turbine blades
2 Boundary layer suction
3 New blade design
4 Porous modeling
5 CFD results
Wake study
Boundary layer flow
6 Aerodynamic performance
7 Goals and future work
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3. Wind Energy: A Clean Energy
The depletion of fossil fuel based electricity production has led to the
growth of renewable energy resources
Wind energy has been expanding with a global production of 35 GW
in 2013
85 countries participated in the commercial wind activity and almost
24 countries reported more than 1 GW capacity by the year end
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4. Challenges for Wind Turbine Manufacturers
Wind turbine blade sizes have grown considerably throughout the
years.
Large turbine blades
Hub and the tip regions are exposed to weakly correlated perturbations
Requires long thick profile regions to satisfy structural requirements
Boundary layer control could
Delay separation
Improve aerodynamic performance
Control structural loads
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5. Boundary Layer Suction: A Possible Solution
Prandtl in 1904 demonstrated the e↵ect of boundary layer suction
applied via slit on one side of the cylinder
Mature technology applied in aviation, automotive and other
industries
The focus is on improving the flow at the blade tip and root region,
and maximizing the lift/drag ratio
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7. Data Acquisition and Analysis
The aerodynamic forces on the porous
media would require the following
parameters for its approximation
L =
I
pn.kdA (1)
D =
I
pn.idA (2)
4 p = (
µ
↵
u +
1
2
C⇢ | u | u) 4 x (3)
4x =
4x90
sin(✓)
(4)
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8. Suction Implementation
Figure : Suction = 0.5 m/s
Figure : Suction = 1.5 m/s
Figure : Suction = 1 m/s
Figure : Suction = 2 m/s
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9. Wake Analysis
Figure : 6 , no suction Figure : 6 , suction =0.5 m/s
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10. Wake Analysis
Figure : 12 , no suction
Figure : 12 , suction =0.5 m/s
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11. Boundary Layer Thickness
Figure : 6 , no suction Figure : 6 , suction =0.5 m/s
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12. Boundary Layer Thickness
Figure : 12 , no suction Figure : 12 , suction =0.5 m/s
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15. Aerodynamic Performance
Drag coe cient is reduced for small amount of suction, which increases
considerably beyond the suction velocity of 1 m/s.
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16. Aerodynamic Performance
The maximum lift/drag ratio is achieved at the suction velocity of 0.5 m/s.
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17. Summary
The optimal suction velocity was found to be 0.5 m/s
A delay in transition of flow from laminar to turbulent was observed
for 6 angle of attack
A delay in separation was observed for 12 angle of attack
The total increment of power for the turbine model is 3400 watts for
the distributed suction consumption of 550 watts
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18. Goals and Future Work
Detatched Eddy Simulation (DES) on the 3D blade section to account for
the span-wise flow distribution.
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19. Goals and Future Work
Vorticity distribution around the blade element.
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