347
Chapter 10
Wind Turbines
© Springer Science+Business Media Dordrecht 2015
E. Dick, Fundamentals of Turbomachines, Fluid Mechanics and Its Applications 109,
DOI 10.1007/978-94-017-9627-9_10
Abstract In this chapter, we discuss the different types of wind turbines and the
basic technical aspects of large wind turbines for electricity generation. We analyse
the performance of wind turbines and discuss their adaptation to a wind regime.
10.1 Wind Energy
Wind is air circulation in the terrestrial atmosphere as a consequence of irregular
warming by the sun. Wind energy systems use the kinetic energy of the wind. We
generally speak of a Wind Energy Conversion System (WECS). Mostly, a system
for electricity generation encompasses a wind turbine rotor, a gearbox, a generator
and a tower. The term Wind Turbine (WT) is commonly used to name the whole.
A particular feature of wind energy is its very diffuse character. The yearly average wind speed at 50 m height along the West European coast between Brittany and
Denmark is about 7 m/s (about 8.5 m/s at 100 m height). Optimum energy yield
is typically obtained by designing the system such that maximum power on the
generator (called rated power) is reached at a wind speed (called rated wind speed)
about 50 % higher than the yearly average speed (see Sect. 10.4: wind regime). The
energy flux of the undisturbed wind through a plane surface (area A) perpendicular
to the wind direction is (mass flow rate × kinetic energy):
(10.1)
To ρ= 1.2 kg/m
3
and v = 12.5 m/s corresponds about 1200 W/m
2
. A wind energy
system converts nearly 45 % of that (see Sect. 10.3: performance). This results in a
net power density of about 500 W/m
2
. A rated power of 1 MW requires a throughflow surface of about 2000 m
2
, corresponding to a circle with a diameter of about
50 m. This demonstrates that large power wind energy conversion systems require
great dimensions.
2
3
1
1
2
2
0
.
P
Av v
v A
r
r
=
=
Chapter 10
Wind Turbines
© Springer Science+Business Media Dordrecht 2015
E. Dick, Fundamentals of Turbomachines, Fluid Mechanics and Its Applications 109,
DOI 10.1007/978-94-017-9627-9_10
Abstract In this chapter, we discuss the different types of wind turbines and the
basic technical aspects of large wind turbines for electricity generation. We analyse
the performance of wind turbines and discuss their adaptation to a wind regime.
10.1 Wind Energy
Wind is air circulation in the terrestrial atmosphere as a consequence of irregular
warming by the sun. Wind energy systems use the kinetic energy of the wind. We
generally speak of a Wind Energy Conversion System (WECS). Mostly, a system
for electricity generation encompasses a wind turbine rotor, a gearbox, a generator
and a tower. The term Wind Turbine (WT) is commonly used to name the whole.
A particular feature of wind energy is its very diffuse character. The yearly average wind speed at 50 m height along the West European coast between Brittany and
Denmark is about 7 m/s (about 8.5 m/s at 100 m height). Optimum energy yield
is typically obtained by designing the system such that maximum power on the
generator (called rated power) is reached at a wind speed (called rated wind speed)
about 50 % higher than the yearly average speed (see Sect. 10.4: wind regime). The
energy flux of the undisturbed wind through a plane surface (area A) perpendicular
to the wind direction is (mass flow rate × kinetic energy):
(10.1)
To ρ= 1.2 kg/m
3
and v = 12.5 m/s corresponds about 1200 W/m
2
. A wind energy
system converts nearly 45 % of that (see Sect. 10.3: performance). This results in a
net power density of about 500 W/m
2
. A rated power of 1 MW requires a throughflow surface of about 2000 m
2
, corresponding to a circle with a diameter of about
50 m. This demonstrates that large power wind energy conversion systems require
great dimensions.
2
3
1
1
2
2
0
.
P
Av v
v A
r
r
=
=