Patent ID: 8807940

Claim:
A blade ( 10 ) for a wind turbine rotor with a hub, the blade extending in a longitudinal direction along a longitudinal axis and having a root area ( 16 ) closest to the hub and a tip region furthest away from the hub, the blade ( 10 ) along at least a portion of the longitudinal direction of the blade having an envelope, which defines an airfoil profile having, in normal operation, a pressure side ( 20 ) and a suction side ( 19 ), and further having a leading edge ( 18 ) and a trailing edge ( 17 ), which edges define an airfoil chord line extending between them, the blade ( 10 ) including adjustable lift-regulating means extending in the longitudinal direction of the blade ( 10 ), and activating means by means of which the lift-regulating means can be adjusted and thus alter the aerodynamic properties of the blade ( 10 ), the lift-regulating means being adapted so that by activation of the activating means, the lift can be reduced in a zone extending in the longitudinal direction of the blade ( 10 ) from a first position in proximity to the blade tip ( 14 ) to a second position between the first position and the root area ( 16 ) and this second position being variable in the longitudinal direction of the blade, characterised in that the lift-regulating means are formed of a plurality of adjacent longitudinally extending zones arranged from the tip region of the blade towards the root area on the trailing edge of the blade, each zone comprising at least one slot ( 12 , 13 , 15 ) or a number of holes ( 42 , 43 , 45 , 52 , 53 , 55 ), each zone being controlled by a separate interior cavity, thereby allowing the interior cavity ( 22 , 23 , 25 ) of the blade ( 10 ) to communicate with the exterior, and the lift-regulating means being adjustable by means of one or more activating means to regulate the amount of air emitted from the interior cavity ( 22 , 23 , 25 ) to the exterior to alter the aerodynamic properties of the blade ( 10 ) such that when the activating means are activated, the lift is minimized.