Wind Turbine Airfoils and Rotor Wakes - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 386

airfoils such as the NACA 4415 and the LS(1)-0413 Mod. The SERI S805A also has the
lowest C L, max , to prevent overpowering the generator of a fixed pitch turbine in high winds.
Unlike the NACA 4415, the C L,max of the new airfoil has minimal sensitivity to surface rough-
ness. This can be a pronounced performance advantage, as illustrated in Figure 6-5.

Table 6-1.
Properties of the SERIS805A Airfoil Compared to Standard Wing Airfoils
[Tangler and Somers 1986]

Airfoil
N R = l x 10 6

Thickness
ratio

Max. lift
coefficien t

Min. drag
coefficient

Lift-to-drag ratio
at C L = 0.7

Moment coef.
at a = 0

SERI S805A 0.135 1.2 0.007 90 -0.05

NACA 4415 0.150 1.4 0.009 85 -0.08

NACA 23012 0.120 1.3 0.009 70 -0.01

LS(1)-0413 Mod 0.130 1.5 0.008 86 -0.10

Figure 6-8. Contours of the SERI S812/S813/S814 series of airfoils designed speci-
fically for fixed-pitch HAWTs with diameters from 21 m to 35 m. (a) Tip region
( r/R » 0.95) (b) Primary outboard airfoil ( r/R » 0.75) (c) Root region ( r/R » 0.40)
[Tangler 1987, Tangler and Somers 1995]