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1. Jarek Puczylowski - AG TWiSt /
ForWind
Jarek
Wind Energy lecture 02.12.2010 1

2. Wind Energy lecture 02.12.2010 2

3. Outline
- variety of wind turbines / classification
- drag coefficient and drag force (example: Persian Windmill)
- aerodynamics of an airfoil
- lift coefficient and lift force (example: Darrieus Rotor)
- history of wind turbines
Wind Energy lecture 02.12.2010 3

4. variety of wind turbines
Wind Energy lecture 02.12.2010 4

5. Jarek Puczylowski - AG TWiSt /
ForWind
different kinds of WECs
horizontal axis
wind turbine
wind turbine
vertical axis
wind turbine
Wind Energy lecture 02.12.2010 5

6. Jarek Puczylowski - AG TWiSt /
ForWind
different kinds of WECs
“drag” based
wind turbines
wind turbine
“lift” based
wind turbines
Wind Energy lecture 02.12.2010 6

7. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
What is drag?
wind velocity v
Wind Energy lecture 02.12.2010 7

8. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
power of the wind
What is drag?
force acting on the body?
wind velocity v
Wind Energy lecture 02.12.2010 8

9. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
power of the wind
What is drag?
force acting on the body?
wind velocity v
Wind Energy lecture 02.12.2010 9

10. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
power of the wind
What is drag?
force acting on the body?
different shapes have different
air resistances, i.e. different
wind velocity v cd = 0,34 drag coefficients cd
cd = 1,33
Wind Energy lecture 02.12.2010 10

11. Jarek Puczylowski - AG TWiSt /
ForWind
Wind Energy lecture 02.12.2010 11

12. Jarek Puczylowski - AG TWiSt /
ForWind
cd is dependent on shape and Re
sphere
Wind Energy lecture 02.12.2010 12

13. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
Persian windmill
year 500-900 a.d.
How can we estimate the
maximum power?
Wind Energy lecture 02.12.2010 13

14. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
power estimation of a
persian windmill
v = const
cp
cd = 1.1
cp,max =0,16
tip speed ratio
tip speed ratio
tip speed ratio for drag force
based wind turbines < 1
Wind Energy lecture 02.12.2010 14

15. Jarek Puczylowski - AG TWiSt /
ForWind
drag force based wind turbines
Wind Energy lecture 02.12.2010 15

16. Jarek Puczylowski - AG TWiSt /
ForWind
lift force based wind turbines
airfoil design
Wind Energy lecture 02.12.2010 16

17. Jarek Puczylowski - AG TWiSt /
ForWind
lift force based wind turbines
How does lift occur?
FL
vup
vdown
Wind Energy lecture 02.12.2010 17

18. Jarek Puczylowski - AG TWiSt /
ForWind
lift force based wind turbines
Bernoulli Equation
(strong simplification of Navier-Stokes-Eq.,
How does lift occur? i.e. no viscosity, stationary, novorticity)
1 2
FL 2
ρu + p = const
vup
vdown
negative
Wind Energy lecture 02.12.2010 18

19. Jarek Puczylowski - AG TWiSt /
ForWind
lift force based wind turbines
Bernoulli Equation
(strong simplification of Navier-Stokes-Eq.,
How does lift occur? i.e. no viscosity, stationary, novorticity)
1 2
ρu + p = const
2
Pup
Pdown negative
Wind Energy lecture 02.12.2010 19

20. Jarek Puczylowski - AG TWiSt /
ForWind
Why is vup larger than vdown?
Wind Energy lecture 02.12.2010 20

21. Jarek Puczylowski - AG TWiSt /
ForWind
Why is vup larger than vdown?
vup starting vortex
vdown
Wind Energy lecture 02.12.2010 21

22. Jarek Puczylowski - AG TWiSt /
ForWind
Why is vup larger than vdown?
angular momentum
conservation
starting vortex
vup starting vortex
vdown
Wind Energy lecture 02.12.2010 22

23. Jarek Puczylowski - AG TWiSt /
ForWind
Why is vup larger than vdown?
angular momentum
conservation
starting vortex
vup starting vortex
wind velocity circulating vortex vup > vdown
vdown
Wind Energy lecture 02.12.2010 23

24. Jarek Puczylowski - AG TWiSt /
ForWind
Forces acting on an airfoil
Wind Energy lecture 02.12.2010 24

25. Jarek Puczylowski - AG TWiSt /
ForWind
Forces acting on an airfoil
Flift F
wind velocity v Fdrag
1
FD = cD (Re, α) · ρAu 2
2
1
FL = cL (Re, α) · ρAu 2 cL = Lift coefficient
2
Wind Energy lecture 02.12.2010 25

26. Jarek Puczylowski - AG TWiSt /
ForWind
measuring lift (and drag) coefficients of airfoils
2 force sensors measure FL and FD
wind velocity v
80 pressure sensors measure
pressure distribution along the wall
Wind Energy lecture 02.12.2010 26

27. Jarek Puczylowski - AG TWiSt /
ForWind
measuring lift coefficients of airfoils
2 force sensors measure FL and FD
80 pressure sensors measure
pressure distribution along the wall
1
FL = cL (Re, α) · ρAu2
2
Wind Energy lecture 02.12.2010 27

28. Jarek Puczylowski - AG TWiSt /
ForWind
measuring lift coefficients of airfoils
Wind Energy lecture 02.12.2010 28

29. Jarek Puczylowski - AG TWiSt /
ForWind
Lift force based wind turbines
example:
Darrieus
wind turbine
Wind Energy lecture 02.12.2010 29

30. Jarek Puczylowski - AG TWiSt /
ForWind
wind velocity v
tip speed ratio for
Darrieus rotors > 3
total velocity
velocity due to FD
rotation u
FL
Wind Energy lecture 02.12.2010 30

31. Jarek Puczylowski - AG TWiSt /
ForWind
wind velocity v
total velocity
velocity due to FD
rotation u
FL
FD
FL
Wind Energy lecture 02.12.2010 31

32. Jarek Puczylowski - AG TWiSt /
ForWind
wind velocity v
total velocity
velocity due to FD
rotation u
FL FD
FD
FL
Wind Energy lecture 02.12.2010 32

33. Jarek Puczylowski - AG TWiSt /
ForWind
wind velocity v
total velocity
velocity due to FD
rotation u
FL FD
FD
FD
FL
Wind Energy lecture 02.12.2010 33

34. Jarek Puczylowski - AG TWiSt /
ForWind
wind velocity v
0° assist rotation
FD
FL FD
90°oppose 270°oppose
FD rotation
rotation
FD
180° assist rotation FL
Wind Energy lecture 02.12.2010 34

35. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
Denmark 1891
Wind Energy lecture 02.12.2010 35

36. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
Russia 1931
Wind Energy lecture 02.12.2010 36

37. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
USA 1942 - 50kW
Wind Energy lecture 02.12.2010 37

38. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
Germany 1942
Wind Energy lecture 02.12.2010 38

39. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
USA 1943 - 70kW
Wind Energy lecture 02.12.2010 39

40. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
UK 1956 - 100kW
Wind Energy lecture 02.12.2010 40

41. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
Denmark 1957 -200kW
Wind Energy lecture 02.12.2010 41

42. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
France 1958 - 800kW
Wind Energy lecture 02.12.2010 42

43. Jarek Puczylowski - AG TWiSt /
ForWind
History of wind turbines
Germany 1982 - 3000kW
Wind Energy lecture 02.12.2010 43