Disclosed is a surface of the blade having a cylindrical root portion, an airfoil portion and a transition portion connecting the root portion with the airfoil portion, wherein the blade comprises a shoulder at the border between the transition portion to the airfoil portion, wherein the blade comprises an element which is arranged substantially at the root portion and/or at the transition portion which creates a slot between the element and the surface of the blade.
1. A rotor blade having a blade surface, comprising:
a cylindrical root portion;
an airfoil portion;
a transition portion that connects the root portion with the airfoil portion, wherein a shoulder is arranged at a border between the transition portion and the airfoil portion; and
an element arranged on the rotor blade and arranged substantially at the cylindrical root portion and/or at the transition portion and which creates a slot between the element and the surface of the blade.
2. A rotor blade having a blade surface, comprising:
a cylindrical root portion;
an airfoil portion;
a transition portion that connects the root portion with the airfoil portion, wherein a shoulder is arranged at a border between the transition portion and the airfoil portion; and
an element arranged substantially at the cylindrical root portion and/or at the transition portion and which creates a slot between the element and the surface of the blade,
wherein the element extends to the airfoil portion.
3. The rotor blade according to claim 2 , wherein the element has a rectangular or trapezoidal shape in plan view.
4. The rotor blade according to claim 2 , wherein the element has a non-rectangular or non-trapezoidal shape in plan view while a leading edge and a trailing edge of the element are non-parallel aligned to each other.
5. A rotor blade having a blade surface, comprising:
a cylindrical root portion;
an airfoil portion;
a transition portion that connects the root portion with the airfoil portion, wherein a shoulder is arranged at a border between the transition portion and the airfoil portion; and
an element arranged substantially at the cylindrical root portion and/or at the transition portion and which creates a slot between the element and the surface of the blade, and
wherein the element is arranged with respect to a leading edge of the blade such that the leading edge of the blade is parallel aligned to the leading edge of the element.
6. The rotor blade according to claim 1 , wherein the element is arranged with respect to a leading edge of the blade such that the leading edge of the blade is non-parallel aligned to the leading edge of the element.
7. The rotor blade according to claim 1 , wherein the element is arranged with respect to the leading edge of the blade such that the leading edge of the blade is parallel aligned to a trailing edge of the element.
8. The rotor blade according to claim 1 , wherein the element is arranged with respect to the leading edge of the blade such that the leading edge of the blade is non-parallel aligned to a trailing edge of the element.
9. The rotor blade according to claim 1 , wherein the shape of the element is flat in cross-section.
10. The rotor blade according to claim 1 , wherein the shape of the element is bent in cross-section.
11. The rotor blade according to claim 1 , wherein the shape of the element is arcuate curved in cross-section.
12. The rotor blade according to claim 1 , wherein the element is fastened to the surface of the blade via a fastening device to assure the creation of the slot between the element and the surface of the blade.
13. The rotor blade according to claim 1 , wherein the element at least partly projects over the leading edge and/or over the trailing edge of the blade.
14. The rotor blade according to claim 1 wherein the leading edge of the element is arranged in front of the leading edge of the blade and the element is curved clockwise, as seen from the blade root towards the blade tip, such that the angle between the leading edge and the trailing edge of the element is between 30° and 75°.
15. The rotor blade according to claim 1 , wherein the element has a rectangular or trapezoidal shape in plan view.
16. The rotor blade according to claim 1 , wherein the element has a non-rectangular or non-trapezoidal shape in plan view while a leading edge and a trailing edge of the element are non-parallel aligned to each other.