Rotor assembly for a wind turbine and method of assembling the same

1. A wind turbine system comprising:

a stator configured to generate electricity; and

a rotor rotatably coupled to the stator, said rotor comprising;

a hub rotatable about an axis of rotation and comprising an external surface that is offset at a first angle with respect to the axis of rotation; and

a plurality of rotor blades spaced circumferentially about said hub, each of said rotor blades having a spanwise axis extending from a blade root located at a hub side of the blade to a blade tip located at an end opposite the blade root such that said plurality of rotor blades are rotatable through a plane of rotation extending about said axis of rotation, said plane of rotation is defined as substantially perpendicular to said axis of rotation, wherein each of said blade roots is coupled substantially perpendicular to said hub at a second angle upstream with respect to the plane of rotation such that an entirety of the spanwise axis of at least one of said rotor blades is even with, or offset a distance upstream from, said plane of rotation and at least one of said blade tips is offset a distance upstream from said plane of rotation, wherein

said hub comprises a first end having a first radius of curvature with respect to the axis of rotation and comprising a second end having a second radius of curvature with respect to the axis of rotation, and

the second radius of curvature is larger than the first radius of curvature.

2. A wind turbine system in accordance with claim 1 , wherein each of said rotor blades comprises a one-piece and uninterrupted, curved span comprising a uniform radius of curvature.

3. A wind turbine system in accordance with claim 2 , wherein each of the said rotor blades comprises a substantially straight blade section extending along the length of each rotor blade from a blade first end to a second location along the blade length that is radially outward from said blade first end.

4. A wind turbine system in accordance with claim 3 , wherein said straight blade section extends along the length of said rotor blade from said blade first end to a location from about ⅓ of the blade length to about ½ of the blade length.

5. A wind turbine system in accordance with claim 1 , wherein said plurality of rotor blades is offset a distance from a perpendicular axis measured from a wind turbine hub.

6. A wind turbine system in accordance with claim 1 , wherein said offset distance ranges from about 0.2 meters to about 5 meters.

7. A wind turbine system in accordance with claim 1 , wherein the second angle measured from at least one blade tip to said plane of rotation ranges from about 0.2 degrees to about 20 degrees.

8. A rotor assembly comprising:

a hub rotatable about an axis of rotation; and

a plurality of rotor blades spaced circumferentially about said hub, each of said rotor blades having a spanwise axis extending from a blade root located at a hub side of the blade to a blade tip located at an end of said blade opposite the blade root such that said plurality of rotor blades are rotatable through a plane of rotation extending about said axis of rotation, said plane of rotation is defined as substantially perpendicular to said axis of rotation, wherein each of said blade roots is coupled to said hub at an angle with respect to the plane of rotation such that an entirety of the spanwise axis of each of said rotor blades is continuous and uninterrupted and even with, or offset a distance upstream from, said plane of rotation and at least one of said blade tips is offset a distance upstream from said plane of rotation, wherein

said hub comprises a first end having a first radius of curvature with respect to the axis of rotation and comprising a second end having a second radius of curvature with respect to the axis of rotation, and

the second radius of curvature is larger than the first radius of curvature.

9. A rotor assembly in accordance with claim 8 , wherein each of said rotor blades comprises a curved span comprising at least one of a uniform radius of curvature and a non-uniform radius of curvature.

10. A rotor assembly in accordance with claim 9 , wherein each of said plurality of rotor blades comprises a substantially straight blade section extending along the length of said rotor blade from a blade first end to a second location along the blade length that is radially outward from said blade first end.

11. A rotor assembly in accordance with claim 10 , wherein said straight blade section extends along the length of said rotor blade from the blade first end to a location from about ⅓ of the blade length to about ½ of the blade length.

12. A rotor assembly in accordance with claim 8 , wherein each of said rotor blades is offset a distance from a perpendicular axis measured from a wind turbine hub.

13. A rotor assembly in accordance with claim 8 , wherein said offset distance ranges from about 0.2 meters to about 5 meters.

14. A rotor assembly in accordance with claim 8 , wherein offset angles measured from said blade tips to said plane of rotation range from about 0.2 degrees to about 20 degrees.

15. A method of assembling a wind turbine system comprising:

providing a hub rotatable about an axis of rotation, the hub comprising an external surface that is offset at a first angle with respect to the axis of rotation; and

coupling a plurality of rotor blades circumferentially about the hub, wherein each of said rotor blades has a spanwise axis that extends from a blade root located at a hub side of the blade to a blade tip located at an end of said blade opposite the blade root such that said plurality of blades are rotatable through a plane of rotation extending about said axis of rotation, said plane of rotation is defined as substantially perpendicular to said axis of rotation, wherein each of said blade roots is coupled substantially perpendicular to said external surface at a second angle upstream with respect to the plane of rotation such that an entirety of the spanwise axis of each of said rotor blades is even with, or offset a distance upstream from, said plane of rotation and at least one of said blade tips is offset a distance upstream from said plane of rotation, wherein

said hub comprises a first end having a first radius of curvature with respect to the axis of rotation and comprising a second end having a second radius of curvature with respect to the axis of rotation, and

the second radius of curvature is larger than the first radius of curvature.

16. A method in accordance with claim 15 , comprising fabricating the plurality of rotor blades with at least one of a uniform radius of curvature and a non-uniform radius of curvature.

17. A method in accordance with claim 16 , comprising fabricating the plurality of rotor blades with a substantially straight blade section extending along the length of the blade from a blade first end to a second location along the blade length that is radially outward from the blade first end.

18. A method in accordance with claim 17 , comprising fabricating the plurality of blades such that the straight blade section extends along the length of the blade from the blade first end to a location from about ⅓ of the blade length to about ½ of the blade length.

19. A method in accordance with claim 15 , wherein the coupling the plurality of rotor blades circumferentially about the hub further comprises offsetting the distance of the blade tips from the plane of rotation by about 0.2 meters to about 5 meters.

20. A method in accordance with claim 15 , wherein coupling the plurality of rotor blades circumferentially about the hub further comprises offsetting the blade tips by angles measured from the blade tips to the plane of rotation by about 0.2 degrees to about 20 degrees.

21. The wind turbine system of claim 1 , wherein the first angle is approximately equal to the second angle.