| dc.description.abstract | The wake effect of yawing an upstream turbines
is of interest in order to increase power production. In this
study, the case of yawing is considered as asymmetric do to
the tower and rotor rotation, and measurements have been
performed in a wind tunnel. The rotational effects when yawing
are obtained by investigating the difference between a disc and a
rotor with the same drag and diameter. This is performed during
a tower-symmetrical setup, and shows that the wake deflects
approximately 1 radius for the disc and significantly less for the
rotor at optimal tip speed ratio. The disc wake is similar to a jet
shape in a crossflow and counter-rotating vortices are present,
which is not the case for the rotor.
Moreover, the differences between yawing in the different
direction are investigated and show that for positive yaw-angles,
the wake spreads more out and deflects more to the side and
to the floor. Furthermore, for negative yaw-angles, the wake is
located closer to downstream the rotor centre. These differences
are slightly less present during shear flow conditions, in addition
to a more sideways deflected wake. | |
