Page 150 - Wind Energy Handbook
P. 150
124 AERODYNAMICS OF HORIZONTAL-AXIS WIND TURBINES
angles the correspondence is much closer. It should be noted that the mean yawing
moment is not zero and that the sign of the moment, being negative, means that it
endeavours to restore the rotor axis to alignment with the wind direction.
The yawing moment comparison is a test of the usefulness of the theory devel-
oped in this section and it would seem that for general engineering purposes it
passes the test.
The measured tilting moments (Figure 3.69) appear to be of about the amplitude
for all three yaw angles whereas the calculated moments (Figure 3.70) increase with
1.0
0.0
M tilt (Nm) yaw = 10˚
yaw = 20˚
yaw = 30˚
-1.0
-2.0
0 90 180 270 360
Azimuth angle
Figure 3.69 Measured Tilt Moments on the Delft Turbine, (Snel and Schepers, 1995)
1.0
0.5
Tilting moment in N m -0.5 10˚
0.0
20˚
30˚
-1.0
-1.5
-2.0
0 90 180 270 360
Azimuth angle
Figure 3.70 Calculated Tilt Moments on the Delft Turbine
