Implementation of the ‘smart’ rotor concept - Wind Power Generation and Wind Turbine Design - page 497

5.3 Results and Discussion
The results of the fi rst set are promising. Here the focus will be on the results on
the step experiments. See van Wingerden et al . [113] for details. In these experi-
ments a step, simulating a gust, was put on the pitch of the blade which triggered
a sudden change in lift. This was fi rstly done without controlling the fl aps and
secondly with feedback control. The results in two cases, a = 6˚ (around maximum
C L / C D ) and a =10˚ (higher than the static stall angle), can be seen in Figs. 21 and 22.
A signifi cant reduction in the vibration behavior, as well as a reduction of the fi rst
peak can be observed.
Observing Figs. 21 and 22 and an important conclusion can be drawn: the con-
trol system based on structural response is only partially able to mitigate the
Figure 21: Strain signal at the root as a result of a step on the pitch at 6˚ angle of
attack (close to maximum C L /C D , desired operating point for the DU-
96 aerofoil).
Figure 22: Strain signal at the root as a result of a step on the pitch at 10˚ angle of
attack (higher than the static stall angle).