Device for reducing oscillations in a wind turbine blade during standstill and method of using same

A device for fitting to a wind turbine blade during turbine standstill to reduce risk of blade oscillation, comprising:

• an elongate flow-disrupting flexible sleeve for fitting over a blade tip and extending part-way along a length of the wind turbine blade, the sleeve defining a longitudinal direction and a lateral direction, the sleeve comprising:
• a tip end which in use overlies the blade tip,
• an open end spaced from the tip end in the longitudinal direction,
• a first region extending in the longitudinal direction and which in use overlies a blade leading edge,
• a slit opposite the first region and extending in the longitudinal direction, the slit defining a first slit edge and a second slit edge spaced from the first slit edge in the lateral direction to define an opening through the sleeve from an outer surface of the sleeve to an inner surface of the sleeve, wherein in use the first slit edge is on one lateral side of a blade trailing edge, the second slit edge on the other lateral side of the blade trailing edge, and the blade trailing edge projects through the opening defined by the slit in the sleeve, and
• tensioning bands on the sleeve adjacent the first and second slit edges of the slit for tensioning the sleeve in the longitudinal direction.