Negative tip vortices blade
A design for wind turbine rotor blades, aircraft wings, and/or other aerodynamic applications which may reduce the vorticity downstream and thus improve lift is described. The blade designs may include an increase in the blade chord towards the tip of the blade, a change in the twist angle at least once along the length of the blade, and/or a change in the thickness of the blade at least once along the length of the blade. These changes individually or in combination may allow for the creation of a counter-rotating vortex behind the blade, increasing power generation and/or lift.
1. A blade comprising:
a length having a first end and a second end; and
a leading edge;
a tailing edge;
a twist; and
a chord between the leading edge and the tailing edge; wherein:
the chord is substantially perpendicular to the length,
the chord has a local chord minimum at a first inflection point,
the chord has a local chord maximum at a second inflection point,
the local chord maximum is closer to the second end than the local chord minimum,
the twist has a local angle minimum at the first inflection point,
the twist has a local angle maximum at the second inflection point, and
the local angle maximum is closer to the second end than the local angle minimum.
2. The blade of claim 1 , wherein:
the local angle maximum is in the range of approximately 1° to approximately 15° larger than the local angle minimum.
3. The blade of claim 1 , wherein:
the first inflection point is located at approximately 90% of the length.
4. The blade of claim 1 , wherein:
the first inflection point is located at approximately 95% of the length.
5. The blade of claim 1 , wherein:
the first inflection point is located at approximately 97% of the length.
6. The blade of claim 1 , wherein:
the second inflection point is located at approximately 90% of the length.
7. The blade of claim 1 , wherein:
the second inflection point is located at approximately 95% of the length.
8. The blade of claim 1 , wherein:
the second inflection point is located at approximately 97% of the length.
9. The blade of claim 1 , wherein:
the local chord maximum is in the range of 0.5 m to 5 m larger than the local chord minimum.
10. The blade of claim 1 , wherein:
the wind turbine blade has a power coefficient in the range of approximately 0.45 to approximately 0.55.
11. The blade of claim 1 , wherein:
the wind turbine blade has a thrust coefficient in the range of approximately 0.75 to approximately 0.95.
12. A blade comprising:
a length having a first end and a second end; and
a leading edge;
a tailing edge;
a twist; and
a chord between the leading edge and the tailing edge; wherein:
the chord is substantially perpendicular to the length,
the chord has a first length at a first inflection point,
the chord has a second measurement at a second inflection point,
the chord has a third measurement at a third inflection point,
the chord has a fourth measurement at a fourth inflection point, and
the third measurement is less than the second measurement and the fourth measurement the twist comprises:
a first pitch angle at the first inflection point;
a second pitch angle at the second inflection point;
a third pitch angle at the third inflection point; and
a fourth pitch angle at the fourth inflection point; wherein:
the third pitch angle is less than the second pitch angle and the fourth pitch angle.
13. The blade of claim 12 , wherein:
the second pitch angle and the fourth pitch angle are in the range of approximately 1° to approximately 15° larger than the third pitch angle.
14. The blade of claim 12 , wherein:
the second measurement is approximately 4 m larger than the third measurement, and
the fourth measurement is approximately 1 m larger than the third measurement.
15. The blade of claim 12 , wherein:
the chord has a fifth measurement at the second end, and
the fifth measurement is smaller than the first measurement, the second measurement, the third measurement, or the fourth measurement.
16. The blade of claim 12 , wherein:
the third inflection point and the fourth inflection point are located within approximately 90% of the length.
17. The blade of claim 12 , wherein:
the wind turbine blade has a power coefficient in the range of approximately 0.45 to approximately 0.55.
18. The blade of claim 12 , wherein:
the wind turbine blade has a thrust coefficient in the range of approximately 0.75 to approximately 0.95.