Wind energy I. Lesson 6. Wind turbines in general P2

Jarek Puczylowski - AG TWiSt / ForWind

Wind Energy lecture 02.12.2010 1

Jarek

Wind Energy lecture 02.12.2010 2

Wind Energy lecture 02.12.2010 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 4

variety of wind turbines

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

different kinds of WECs

5

wind turbine

horizontal axiswind turbine

vertical axiswind turbine

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

different kinds of WECs

6

wind turbine

“drag” based wind turbines

“lift” based wind turbines

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

7

drag force based wind turbines

What is drag?

wind velocity v

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

8

drag force based wind turbines

What is drag?

wind velocity v

power of the wind

force acting on the body?

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

9

drag force based wind turbines

What is drag?

wind velocity v

power of the wind

force acting on the body?

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

10

drag force based wind turbines

What is drag?

wind velocity v

power of the wind

force acting on the body?

different shapes have different air resistances, i.e. different

drag coefficients cdcd = 0,34

cd = 1,33

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

11

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

12

sphere

cd is dependent on shape and Re

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

13

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

Jarek Puczylowski - AG TWiSt / ForWind

14

drag force based wind turbines

v = const

cd = 1.1

power estimation of a persian windmill

tip speed ratio

cp

tip speed ratio

cp,max =0,16

tip speed ratio for drag force based wind turbines < 1

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

15

drag force based wind turbines

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

16

lift force based wind turbines

airfoil design

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

17

lift force based wind turbines

How does lift occur?

vup

vdown

FL

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

18

lift force based wind turbines

How does lift occur?

vup

vdown

Bernoulli Equation(strong simplification of Navier-Stokes-Eq.,

i.e. no viscosity, stationary, novorticity)

1

2!u2

+ p = const

negative

FL

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

19

lift force based wind turbines

How does lift occur?Bernoulli Equation

(strong simplification of Navier-Stokes-Eq., i.e. no viscosity, stationary, novorticity)

1

2!u2

+ p = const

negative

Pup

Pdown

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

20

Why is vup larger than vdown?

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

21

Why is vup larger than vdown?

vup

vdown

starting vortex

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

22

Why is vup larger than vdown?

vup

vdown

starting vortex

angular momentumconservation

starting vortex

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

23

Why is vup larger than vdown?

vup

vdown

starting vortex

angular momentumconservation

starting vortex

wind velocity circulating vortex vup > vdown

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

24

Forces acting on an airfoil

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

25

Forces acting on an airfoil

FL = cL(Re,!) · 12"Au2

FD = cD(Re,!) · 12"Au2

Flift

Fdrag

F

cL = Lift coefficient

wind velocity v

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

26

measuring lift (and drag) coefficients of airfoils

2 force sensors measure FL and FD

80 pressure sensors measure pressure distribution along the wall

wind velocity v

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

27

measuring lift coefficients of airfoils

FL = cL(Re,!) · 12"Au2

2 force sensors measure FL and FD

80 pressure sensors measure pressure distribution along the wall

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

28

measuring lift coefficients of airfoils

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

29

Lift force based wind turbines

example:

Darrieus wind turbine

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

30

wind velocity v

velocity due to rotation u

total velocity

FL

FD

tip speed ratio for Darrieus rotors > 3

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

31

wind velocity v

velocity due to rotation u

total velocity

FL

FD

FD

FL

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

32

wind velocity v

velocity due to rotation u

total velocity

FL

FD

FD

FL

FD

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

33

wind velocity v

velocity due to rotation u

total velocity

FL

FD

FD

FL

FD

FD

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

34

wind velocity v

FL

FD

FD

FL

FD

FD

0° assist rotation

180° assist rotation

90°oppose rotation

270°oppose rotation

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

35

History of wind turbines

Denmark 1891

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

36

History of wind turbines

Russia 1931

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

37

History of wind turbines

USA 1942 - 50kW

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

38

History of wind turbines

Germany 1942

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

39

History of wind turbines

USA 1943 - 70kW

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

40

History of wind turbines

UK 1956 - 100kW

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

41

History of wind turbines

Denmark 1957 -200kW

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

42

History of wind turbines

France 1958 - 800kW

Wind Energy lecture 02.12.2010

Jarek Puczylowski - AG TWiSt / ForWind

43

History of wind turbines

Germany 1982 - 3000kW