Wind Energy

[W/m 2 ]
q t [W/m
5000
4000
3000
2000
1000
0
AoA 12˚ 12
AoA 22˚
57 Influence of the Type and Size of Wind Turbines 307
M1 M2 M3 M4
(a)
Q t [kW]
[kW]
250
200
150
100
50
AoA 12 12˚
AoA 2˚ 2
0
600 2100 3600 5100 6600
Pr [kW]
(b)
Qt /P / r [%]
[%]
20
16
12 12
8
4
AoA 12˚ 12
AoA 2˚ 2
0
600 2100 3600 5100 6600
P r [kW]
Fig. 57.1. Specific anti-icing power requirement (a), total anti-icing power requirement
(b), and anti-icing-power to rated-power (c) between the two extreme angles
of attack
Table 57.3. Turbine data used for a comparison of the anti-icing thermal power
with respect to machine type
Pr (kW) D (m) Z (–) Nr (rpm) Vr (m s −1 ) NACA airfoil L (m) H (m)
M3 1,630 61.12 3 22.15 12.5 44xx 24.1 0.32
M5 1,571 61.12 2 22.15 12.5 44xx 24.1 0.32
M6 1,421 61.12 1 22.15 12.5 44xx 24.1 0.32
However, the ratio of anti-icing power to rated power output (Fig. 57.1c) is
unfavourable for the smaller turbines, growing from 4 to 10% for the largest
to 11–16% for the smallest one.
57.4 Anti-Icing Power as a Function of the Machine
Type
Three wind turbines were considered having almost the same rated power and
different number of blades (see Table 57.3).
Figure 57.2a shows that larger heat fluxes have to be supplied to the wider
cord rotor (the single-bladed one) since the heated area lies close to the leading
edge. However, the anti-icing power requirement Qt (Fig. 57.2b), which
depends on the number of blades, decreases considerably from the three-to
the single-bladed turbine, in a manner that is nearly proportional to the number
of blades. Figure 57.2c shows that the reduction of the number of blades
reduces the ratio of rotor anti-icing thermal power to rated turbine power.
57.5 Conclusions
The presented analysis showed that three-bladed turbines with a rated power
output between 1 and 6 MW, depending on environmental conditions and for
(c)