Wind turbine blade having twisted spar web

Abstract

A radially twisted wind turbine blade ( 10 ), including a radially twisted spar web ( 122 ), wherein a center ( 78 ) of a radial cross section of a base ( 12 ) of the blade rotates within a plane of rotation ( 80 ), and wherein at a base ( 12 ), a radial cross section of the spar web forms a first angle ( 82 ) with the plane of rotation, and at a tip ( 32 ) a radial cross section of the spar web forms a second angle ( 130 ) with the plane of rotation different than the first angle.

The invention claimed is: 
     
         1 . A radially twisted wind turbine blade, comprising a radially twisted spar web, wherein a center of a radial cross section of a base of the blade rotates within a plane of rotation, and wherein at a base, a radial cross section of the spar web forms a first angle with the plane of rotation, and at a tip a radial cross section of the spar web forms a second angle with the plane of rotation different than the first angle. 
     
     
         2 . The wind turbine blade of  claim 1 , wherein the first angle is less than the second angle. 
     
     
         3 . The wind turbine blade of  claim 2 , wherein the first angle is less than 45 degrees, and the second angle is greater than 45 degrees. 
     
     
         4 . The wind turbine blade of  claim 1 , wherein a twist of the spar web is curvilinear from a base of the spar web to a tip of the spar web. 
     
     
         5 . The wind turbine blade of  claim 1 , wherein from a base of the spar web to a tip of the spar web the spar web is located between a pressure side spar cap and a suction side spar cap to maximize an average length of the spar web between the pressure side spar cap and the suction side spar cap. 
     
     
         6 . The wind turbine blade of  claim 1 , wherein a tangent of a leading edge of the blade forms right angles with a tangent line of a pressure side of the blade and a tangent line of a suction side of the blade, and the spar web spans between a tangent point of the pressure side tangent line and a tangent point of the suction side tangent line. 
     
     
         7 . The wind turbine blade of  claim 1 , further comprising spar caps secured to ends of the spar web, wherein the spar web and the spar caps are configured to enable aeroelastic deflection during high wind loading. 
     
     
         8 . A radially twisted wind turbine blade, comprising a radially twisted spar web configured to hold a pressure side spar cap and a suction side spar cap in a spaced-apart relationship,
 wherein a center of a radial cross section of a base of the blade rotates within a plane of rotation,   wherein a base, the spar web is oriented such that it resists deflection of the spar web in a direction parallel to the plane of rotation more than it resists deflection of the spar web in a direction perpendicular to the plane of rotation; and   wherein at a tip the spar web is oriented such that it resists deflection of the spar web in the direction normal to the the plane of rotation more than it resists deflection of the spar web in the direction parallel to the plane of rotation.   
     
     
         9 . The wind turbine blade of  claim 8 , wherein the spar web further enables aeroelastic deflection during high wind loading. 
     
     
         10 . The wind turbine blade of  claim 8 , wherein from a base of the spar web to a tip of the spar web the spar web is located between the pressure side spar cap and the suction side spar cap to maximize an average length of the spar web between the pressure side spar cap and the suction side spar cap. 
     
     
         11 . The wind turbine blade of  claim 8 , further comprising spar caps secured to ends of the spar web, wherein the spar web and the spar caps are configured to enable aeroelastic deflection during high wind loading. 
     
     
         12 . The wind turbine blade of  claim 8 , wherein a twist of the spar web comprises no abrupt changes. 
     
     
         13 . The wind turbine blade of  claim 8 , wherein a tangent of a leading edge of the blade forms right angles with a tangent line of a pressure side and a tangent line of a suction side, and the spar web spans between a tangent point of the pressure side tangent line and a tangent point of the suction side tangent line. 
     
     
         14 . A radially twisted wind turbine blade, comprising a radially twisted spar web,
 wherein the turbine blade twists from a base of the blade to a tip of the blade,   wherein a center of a radial cross section of the base of the blade rotates within a plane of rotation, and   wherein within each radial cross section of the blade the spar web forms an alignment angle of less than 45 degrees with a direction of a net bending moment.   
     
     
         15 . The wind turbine blade of  claim 14 , wherein the alignment angle is zero within at least one radial cross section. 
     
     
         16 . The wind turbine blade of  claim 14 , wherein for an orientation of the respective spar web in each cross section, the respective spar web is located to maximize an average length of the spar web. 
     
     
         17 . The wind turbine blade of  claim 14 , further comprising spar caps secured to ends of the spar web, wherein the spar web and the spar caps are configured to enable aeroelastic deflection during high wind loading. 
     
     
         18 . The wind turbine blade of  claim 14 , wherein a twist of the spar web is curvilinear from the spar web base to the spar web tip. 
     
     
         19 . The wind turbine blade of  claim 14 , wherein a tangent of a leading edge of the blade forms right angles with a tangent line of a pressure side and a tangent line of a suction side, and the spar web spans between a tangent point of the pressure side tangent line and a tangent point of the suction side tangent line.