Rotor for a wind turbine

Abstract

A rotor for a wind turbine, having a diameter of 50 metres or more, has a blade with at least two blade sections in the lengthwise direction of the blade, where at least one blade section has a curvature along the blade and relative to a second blade section, where said curvature results in the tip end of said blade being offset (x) relative to the axis of the blade root. A ratio (x/L) of the offset (x) relative to a distance (L) from the tip end of the blade to the blade root is between 0 and 0.1.

1 . The rotor for a wind turbine, where the wind turbine comprises at least a tower, a nacelle on top of said tower and a rotor,
 said rotor having a diameter of 50 metres or more,   and being connectable to a substantially horizontal main shaft,   said main shaft being rotatably mounted in said nacelle,   said wind turbine being of the type where the rotor is facing upwind, where said rotor comprises at least one blade, three blades and a hub,   said blades having an elongated shape with a root end and a tip end, where said blades at the root end are connected to said hub and where the interface between   said hub and said blades comprises a pitch mechanism,   further said rotor has a rotor plane, described by the area swept by the blades, said rotor plane being with a cone shape and having an angle towards the upwind direction, where the cone shape, at least partly, originates from the shape of the hub, and where one blade of said rotor has a combined radius specific solidity Sol r  at:   blade radius r=30% of the rotor radius R, where Sol r ≦0.036;   blade radius r=40% of the rotor radius R, where Sol r ≦0.03;   blade radius r=50% of the rotor radius R, where Sol r ≦0.0245;   blade radius r=60% of the rotor radius R, where Sol r ≦0.021;   blade radius r=70% of the rotor radius R, where Sol r ≦0.0175;   blade radius r=80% of the rotor radius R, where Sol r ≦0.014;   blade radius r=90% of the rotor radius R, where Sol r ≦0.0115; and   blade radius r=96% of the rotor radius R, where Sol r ≦0.0095,   and where Sol r  has a level below a linear interpolation between any of the given blade radii,   
       wherein
 a blade of said rotor comprises at least two blade sections in the lengthwise direction of said blade, 
 where at least one blade section has a curvature along the blade and relative to a second blade section, 
 where said curvature results in the tip end of said blade being offset (x) relative to the axis of the blade root, 
 where the ratio (x/L) of the offset (x) relative to a distance (L) from the tip end of the blade to the blade root, said distance (L) being measured perpendicular to the plane of the root end of the blade and said offset (x) being measured as the perpendicular offset from the axis of the blade root is between 0 and 0.1, 
 and that said rotor is with a cone angle (β) between 0 and  10 degrees, said cone angle (β) being measured between the axis of the blade root and perpendicular to the axis of the main shaft.    
 
     
     
         2 . The rotor for a wind turbine according to  claim 1 , wherein a blade of said rotor has a combined radius specific solidity Sol r  at:
 blade radius r=30% of the rotor radius R, where Sol r ≦0.0345;   blade radius r=40% of the rotor radius R, where Sol r ≦0.028;   blade radius r=50% of the rotor radius R, where Sol r ≦0.023;   blade radius r=60% of the rotor radius R, where Sol r ≦0.019;   blade radius r=70% of the rotor radius R, where Sol r ≦0.016;   blade radius r=80% of the rotor radius R, where Sol r ≦0.0125;   blade radius r=90% of the rotor radius R, where Sol r ≦0.01; and   blade radius r=96% of the rotor radius R, where Sol r ≦0.008,   and where Sol r has a level below a linear interpolation between any of the given blade radii.   
     
     
         3 . The rotor for a wind turbine according to  claim 1 , wherein a blade of said rotor has a combined radius specific solidity Sol r  at:
 blade radius r=30% of the rotor radius R, where Sol r ≦0.033;   blade radius r=40% of the rotor radius R, where Sol r ≦0.0255;   blade radius r=50% of the rotor radius R, where Sol r ≦0.021;   blade radius r=60% of the rotor radius R, where Sol r ≦0.017;   blade radius r=70% of the rotor radius R, where Sol r ≦0.0135;   blade radius r=80% of the rotor radius R, where Sol r ≦0.011;   blade radius r=90% of the rotor radius R, where Sol r ≦0.008; and   blade radius r=96% of the rotor radius R, where Sol r ≦0.0065,   and where Sol r  has a level below a linear interpolation between any of the given blade radii.   
     
     
         4 . The rotor for a wind turbine according to  claim 1 , wherein the ratio (x/L) of the offset (x) relative to a distance (L) is between 0.022 and 0.087. 
     
     
         5 . The rotor for a wind turbine according to  claim 1 , wherein the ratio (x/L) of the offset (x) relative to a distance (L) is between 0.033 and 0.054. 
     
     
         6 . The rotor for a wind turbine according to  claim 1 , wherein said rotor is with a cone angle (β) between 1 and 6 degrees, said cone angle (β) being measured between the axis of the blade root and perpendicular to the axis of the main shaft. 
     
     
         7 . The rotor for a wind turbine according  claim 1 , wherein said rotor is with a cone angle (β) between 2 and 5 degrees, said cone angle (β) being measured between the axis of the blade root and perpendicular to the axis of the main shaft.