Patent Application
20120027588
The present disclosure relates in general to wind turbine rotor blades, and more particularly to flaps mounted on the rotor blades.
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Rotor blades in general are increasing in size, in order to become capable of capturing increased kinetic energy. However, the shape of a typical wind turbine rotor blade results in a relatively large separation region, due to the contour of the rotor blade. Specifically, the contour of the inner portion of the rotor blade adjacent to and including the root may cause such separation. In some cases, this inner portion may include 40%, 50% or more of the rotor blade. The separation region causes relatively significant energy losses by creating drag. Further, these losses are amplified as rotor blade sizes are increased.
Thus, an improved rotor blade assembly would be advantageous. For example, a rotor blade assembly that reduces or eliminates the separation region adjacent to the root of the rotor blade would be desired.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one embodiment, a rotor blade assembly for a wind turbine is disclosed. The rotor blade assembly includes a rotor blade having exterior surfaces defining a pressure side, a suction side, a leading edge, and a trailing edge extending in a generally span-wise direction between a tip and a root. The rotor blade assembly further includes a flap extending in the generally span-wise direction from the root towards the tip. The flap includes an inner surface and an outer surface, the inner surface conformingly mounted to at least one of the pressure side, the suction side, or the trailing edge, the outer surface and at least one of the pressure side or the suction side defining a generally continuous aerodynamic surface.
In another embodiment, a method for reducing the separation region of a rotor blade for a wind turbine is disclosed. The method includes mounting a flap to a rotor blade, and rotating the rotor blade on the wind turbine. The rotor blade has exterior surfaces defining a pressure side, a suction side, a leading edge, and a trailing edge extending in a generally span-wise direction between a tip and a root. The flap extends in the generally span-wise direction from the root towards the tip. The flap includes an inner surface and an outer surface, the inner surface conformingly mounted to at least one of the pressure side, the suction side, or the trailing edge, the outer surface and at least one of the pressure side or the suction side defining a generally continuous aerodynamic surface.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Referring to
In some embodiments, the rotor blade 16 may include a plurality of individual blade segments aligned in an end-to-end order from the blade tip 32 to the blade root 34. Each of the individual blade segments may be uniquely configured so that the plurality of blade segments define a complete rotor blade 16 having a designed aerodynamic profile, length, and other desired characteristics. For example, each of the blade segments may have an aerodynamic profile that corresponds to the aerodynamic profile of adjacent blade segments. Thus, the aerodynamic profiles of the blade segments may form a continuous aerodynamic profile of the rotor blade 16. Alternatively, the rotor blade 16 may be formed as a singular, unitary blade having the designed aerodynamic profile, length, and other desired characteristics.
The rotor blade 16 may, in exemplary embodiments, be curved. Curving of the rotor blade 16 may entail bending the rotor blade 16 in a generally flapwise direction and/or in a generally edgewise direction. The flapwise direction may generally be construed as the direction (or the opposite direction) in which the aerodynamic lift acts on the rotor blade 16. The edgewise direction is generally perpendicular to the flapwise direction. Flapwise curvature of the rotor blade 16 is also known as pre-bend, while edgewise curvature is also known as sweep. Thus, a curved rotor blade 16 may be pre-bent and/or swept. Curving may enable the rotor blade 16 to better withstand flapwise and edgewise loads during operation of the wind turbine 10, and may further provide clearance for the rotor blade 16 from the tower 12 during operation of the wind turbine 10.
The rotor blade 16 may further define a chord 42 and a span 44 extending in chord-wise and span-wise directions, respectively. As shown in
Additionally, the rotor blade 16 may define an inner board area 52 and an outer board area 54. The inner board area 52 may be a span-wise portion of the rotor blade 16 extending from the root 34. For example, the inner board area 52 may, in some embodiments, include approximately 33%, 40%, 50%, 60%, 67%, or any percentage or range of percentages therebetween, or any other suitable percentage or range of percentages, of the span 44 from the root 34. The outer board area 54 may be a span-wise portion of the rotor blade 16 extending from the tip 32, and may in some embodiments include the remaining portion of the rotor blade 16 between the inner board area 52 and the tip 32. Additionally or alternatively, the outer board area 54 may, in some embodiments, include approximately 33%, 40%, 50%, 60%, 67%, or any percentage or range of percentages therebetween, or any other suitable percentage or range of percentages, of the span 44 from the tip 32.
As illustrated in
The flap 110 includes an inner surface 112 and an outer surface 114, as shown in
For example,
Further,
As mentioned above, in some embodiments, the inner surface 112 may be mounted to a relatively substantial portion of the pressure side 22 and/or suction side 24. This portion may be defined relative to the local chord 46. For example, the inner surface may be mounted to between approximately 20% and approximately 60%, such as between approximately 20% and approximately 50%, such as between approximately 20% and approximately 40%, such as between approximately 20% and approximately 30%, of the local chord 46 on the pressure side 22 and/or suction side 24. In other embodiments, the inner surface 112 may be mounted to a relatively minimal portion of the pressure side 22 and/or the suction side 24. This portion may also be defined relative to the local chord 46. For example, the inner surface may be mounted to between approximately 0% and approximately 20%, such as between approximately 0% and approximately 15%, such as between approximately 0% and approximately 10%, such as between approximately 0% and approximately 5%, of the local chord 46 on the pressure side 22 and/or suction side 24.
It should be understood that the inner surface 112 may be conformingly mounted to any one or more of the pressure side 22, the suction side 24, or the trailing edge 28, and further that the inner surface 112 may be mounted to a relatively substantial portion or a relatively minimal portion of any one or more of the pressure side 22, the suction side 24, or the trailing edge 28. Further, it should be understood that the relatively substantial portion and relatively minimal portion discussed above are not limited to the above disclosed ranges, and rather that any suitable range or percentage is within the scope and spirit of the present disclosure.
As shown in
The outer surface 114 of the flap 110 may include a pressure side portion 122 and/or a suction side portion 124. The pressure side portion 122 may define a generally aerodynamic surface with the pressure side 22 of the rotor blade 16, as discussed above, while the suction side portion 124 may define a generally aerodynamic surface with the suction side 24, as discussed above. In some embodiments, the outer surface 114 of the flap 110 may include only the pressure side portion 122 and suction side portion 124, which may meet at both generally chord-wise ends of the flap 110, as shown in
In other embodiments, however, the outer surface 114 may further include additional surfaces. For example, in some embodiments, as shown in
The planer portion 126 in exemplary embodiments extends in the generally span-wise direction. Thus, in some embodiments the planer portion 126 may extend generally parallel to the span 44 of the rotor blade 16. Alternatively, however, the planer portion 126 may extend at any suitable angle to the span 44, as desired or required. In further alternative embodiments, the planer portion 126 may extend in any suitable angle relative to the rotor blade 16.
Further, as shown, the planer portion 126 in some embodiments is generally perpendicular to the local chord 46 of the rotor blade 16. Thus, as the planer portion 126 extends, such as in the generally span-wise direction, the planer portion 126 at any location may be generally perpendicular to the local chord 46 at that location. Alternatively, however, the planer portion 126 may be positioned at any suitable angle to perpendicular, or have any other suitable angle relative to the rotor blade 16.
In some embodiments, as shown in
In some embodiments, as shown in
The present disclosure may further be directed to a method for reducing the separation region of a rotor blade 16 for a wind turbine 10. The method includes the step of mounting a flap 110 to a rotor blade 16, as discussed above. The method further includes rotating the rotor blade 16 on the wind turbine 10.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
