Page 428 - Wind Energy Handbook

402 COMPONENT DESIGN

90
Rotational speed = 33 r.p.m., Mean wind speed = 14 m/s, Rated speed = 12 m/s Wind speed (m/s)
Turbulence intensity = 18.4%, Integral length scale = 73.5 m, Bending moment (kNm)
80
Zero wind shear, Shaft tilt w.r.t. mean flow = 13 ,
70

60
50

40
30

20

10
0
0 50 100 150 200 250 300
-10
Time (s)
Figure 7.14 Time History of Flapwise Bending Moment at 12 m Radius and Short-term
Mean Wind Speed for 40 m Diameter Pitch-regulated Machine with Three TR Blades, Based
on Three-dimensional Wind Simulation with 14 m/s Mean

0.4
Pitch-regulated machine
0.35

0.3
Rotational speeds: 33 r.p.m. (pitch-regulated)
Damage number per 2 m/s bin 0.2
and 30 r.p.m. (stall-regulated)
IEC Class A turbulence intensity
Zero wind shear, Shaft tilt w.r.t. mean flow = 13
0.25

0.15

0.1

0.05
Stall-regulated machine
0
0 5 10 15 20 25 30
Mean wind speed (m/s)
Figure 7.15 Variation of Blade Fatigue Damage in Flapwise Bending at 12 m Radius with
Mean Wind Speed, for Similar 40 m Diameter Pitch- and Stall-regulated Machines, Ignoring
Dynamics