DK178360B1

DK178360B1 - Root flap for rotor blade in wind turbine

Info

Publication number: DK178360B1
Application number: DK201270257A
Authority: DK
Inventors: Christian A Carroll
Original assignee: Gen Electric
Priority date: 2011-05-20
Filing date: 2012-05-16
Publication date: 2016-01-11
Also published as: DK201270257A; US20120027588A1; CN102797624A; DE102012104317A1

Abstract

A rotor blade assembly and a method for reducing the separation region of a rotor blade for a wind turbine are 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.

Description

ROOT FLAP FOR ROTOR BLADE IN WIND TURBINEFIELD OF THE INVENTION

[0001] The present disclosure relates in general to wind turbine rotor blades, andmore particularly to flaps mounted on the rotor blades.

BACKGROUND OF THE INVENTION

[0002] Wind power is considered one of the cleanest, most environmentallyfriendly energy sources presently available, and wind turbines have gained increasedattention in this regard. A modem wind turbine typically includes a tower, generator,gearbox, nacelle, and one or more rotor blades. The rotor blades capture kineticenergy of wind using known airfoil principles. The rotor blades transmit the kineticenergy in the form of rotational energy so as to turn a shaft coupling the rotor bladesto a gearbox, or if a gearbox is not used, directly to the generator. The generator thenconverts the mechanical energy to electrical energy that may be deployed to a utilitygrid.

[0003] Rotor blades in general are increasing in size, in order to become capableof capturing increased kinetic energy. However, the shape of a typical wind turbinerotor blade results in a relatively large separation region, due to the contour of therotor blade. Specifically, the contour of the inner portion of the rotor blade adjacentto and including the root may cause such separation. In some cases, this inner portionmay include 40%, 50% or more of the rotor blade. The separation region causesrelatively significant energy losses by creating drag. Further, these losses areamplified as rotor blade sizes are increased.

[0004] EP 2 292 926 discloses a wind turbine blade with high-lift devices in theleading edge and/or trailing edge in the root area. The high lift devices may howeverhave a poor life span as a result of forces exerted on said high lift device duringrotation of the wind turbine blade.

[0005] Thus, an improved rotor blade assembly would be advantageous. Forexample, a rotor blade assembly that reduces or eliminates the separation regionadjacent to the root of the rotor blade would be desired.

BRIEF DESCRIPTION OF THE INVENTION

[0006] Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may be learnedthrough practice of the invention.

[0007] 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 apressure side, a suction side, a leading edge, and a trailing edge extending in agenerally span-wise direction between a tip and a root, and an inner board area. Therotor blade assembly further includes a flap in the inner board area and extending inthe generally span-wise direction from the root towards the tip. The flap includes aninner surface and an outer surface, the inner surface being conformingly mounted toonly one of the pressure side and the suction side, the outer surface and the one of thepressure side and the suction side defining a generally continuous aerodynamicsurface.

[0008] In another embodiment, a method for reducing the separation region of arotor blade for a wind turbine is disclosed. The method includes mounting a flap to arotor blade, and rotating the rotor blade on the wind turbine. The rotor blade hasexterior surfaces defining a pressure side, a suction side, a leading edge, and a trailingedge extending in a generally span-wise direction between a tip and a root, and aninner board area. The flap in the inner board area and extends in the generally span-wise direction from the root towards the tip. The flap includes an inner surface and anouter surface, the inner surface being conformingly mounted to only one of thepressure side and the suction side, the outer surface and the one of the pressure sideand the suction side defining a generally continuous aerodynamic surface.

[0009] These and other features, aspects and advantages of the present inventionwill become better understood with reference to the following description andappended claims. The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and enabling disclosure of the present invention, including the bestmode thereof, directed to one of ordinary skill in the art, is set forth in thespecification, which makes reference to the appended figures, in which:

[0011] FIG. 1 is a side view of a wind turbine according to one embodiment of thepresent disclosure;

[0012] FIG. 2 is a top perspective view of a rotor blade assembly according to oneembodiment of the present disclosure;

[0013] FIG. 3 is a bottom perspective view of the rotor blade assembly of FIG. 2;

[0014] FIG. 4 is a top perspective view of a rotor blade assembly according to another embodiment of the present disclosure;

[0015] FIG. 5 is a bottom perspective view of the rotor blade assembly of FIG. 4;

[0016] FIG. 6 is a cross-sectional view of a rotor blade assembly according to one embodiment of the present disclosure;

[0017] FIG. 7 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure;

[0018] FIG. 8 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure;

[0019] FIG. 9 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure;

[0020] FIG. 10 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure; and,

[0021] FIG. 11 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure.

DETAIFED DESCRIPTION OF THE INVENTION

[0022] Reference now will be made in detail to embodiments of the invention, oneor more examples of which are illustrated in the drawings. Each example is providedby way of explanation of the invention, not limitation of the invention. In fact, it willbe apparent to those skilled in the art that various modifications and variations can bemade in the present invention without departing from the scope or spirit of theinvention. 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 isintended that the present invention covers such modifications and variations as comewithin the scope of the appended claims and their equivalents.

[0023] FIG. 1 illustrates a wind turbine 10 of conventional construction. Thewind turbine 10 includes a tower 12 with a nacelle 14 mounted thereon. A plurality ofrotor blades 16 are mounted to a rotor hub 18, which is in turn connected to a mainflange that turns a main rotor shaft. The wind turbine power generation and controlcomponents are housed within the nacelle 14. The view of FIG. 1 is provided forillustrative purposes only to place the present invention in an exemplary field of use.

It should be appreciated that the invention is not limited to any particular type of windturbine configuration.

[0024] Referring to FIGS. 2 through 11, a rotor blade 16 according to the presentdisclosure may include exterior surfaces defining a pressure side 22 and a suction side24 extending between a leading edge 26 and a trailing edge 28, and may extend froma blade tip 32 to a blade root 34. The exterior surfaces may be generally aerodynamicsurfaces having generally aerodynamic contours, as is generally known in the art.

[0025] In some embodiments, the rotor blade 16 may include a plurality ofindividual blade segments aligned in an end-to-end order from the blade tip 32 to theblade root 34. Each of the individual blade segments may be uniquely configured sothat the plurality of blade segments define a complete rotor blade 16 having adesigned aerodynamic profile, length, and other desired characteristics. For example,each of the blade segments may have an aerodynamic profile that corresponds to theaerodynamic profile of adjacent blade segments. Thus, the aerodynamic profiles ofthe 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 thedesigned aerodynamic profile, length, and other desired characteristics.

[0026] The rotor blade 16 may, in exemplary embodiments, be curved. Curvingof the rotor blade 16 may entail bending the rotor blade 16 in a generally flap wisedirection and/or in a generally edgewise direction. The flapwise direction maygenerally be construed as the direction (or the opposite direction) in which theaerodynamic lift acts on the rotor blade 16. The edgewise direction is generallyperpendicular 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, acurved rotor blade 16 may be pre-bent and/or swept. Curving may enable the rotorblade 16 to better withstand flapwise and edgewise loads during operation of the windturbine 10, and may further provide clearance for the rotor blade 16 from the tower 12during operation of the wind turbine 10.

[0027] The rotor blade 16 may further define a chord 42 and a span 44 extendingin chord-wise and span-wise directions, respectively. As shown in FIGS. 2 through 5,the chord 42 may vary throughout the span 44 of the rotor blade 16. Thus, asdiscussed below, a local chord 46 may be defined for the rotor blade 16 at any pointon the rotor blade 16 along the span 44. Further, the rotor blade 16 may define amaximum chord 48, as shown.

[0028] Additionally, the rotor blade 16 may define an inner board area 52 and anouter board area 54. The inner board area 52 may be a span-wise portion of the rotorblade 16 extending from the root 34. For example, the inner board area 52 may, insome embodiments, include approximately 33%, 40%, 50%, 60%, 67%, or anypercentage or range of percentages therebetween, or any other suitable percentage orrange of percentages, of the span 44 from the root 34. The outer board area 54 maybe a span-wise portion of the rotor blade 16 extending from the tip 32, and may insome embodiments include the remaining portion of the rotor blade 16 between theinner board area 52 and the tip 32. Additionally or alternatively, the outer board area54 may, in some embodiments, include approximately 33%, 40%, 50%, 60%, 67%, orany percentage or range of percentages therebetween, or any other suitable percentageor range of percentages, of the span 44 from the tip 32.

[0029] As illustrated in FIGS. 2 through 11, the present disclosure may further bedirected to a rotor blade assembly 100. The rotor blade assembly 100 may include aflap 110 and the rotor blade 16. The flap 110 is a generally static flap mounted to therotor blade 16 in the inner board area 52 of the rotor blade 100. The flap 110 extendsin the generally span-wise direction from the root 34 towards the tip 32. Thus, oneend of the flap 110 is positioned at the root 34, while the other end is positionedbetween the root 34 and the tip 32 in the inner board area 52. As discussed below, theflap alters the contour of a portion of the rotor blade 16 adjacent to the root 34. Thisalteration reduces or eliminates any separation region in this portion of the rotor blade 16, and further reduces the drag associated with the rotor blade 16 and increases theperformance rotor blade 16.

[0030] The flap 110 includes an inner surface 112 and an outer surface 114, asshown in FIGS. 2 through 11. The inner surface 112 is conformingly mounted to atleast one of the pressure side 22, the suction side 24, or the trailing edge 28. Thus, theaerodynamic contour of the inner surface 112 conforms to at least one of the pressureside 22, the suction side 24, or the trailing edge 28, such that when the flap 110 ismounted to the rotor blade 16, relatively little or no air may pass between the innersurface 112 and the pressure side 22, the suction side 24, and/or the trailing edge 28.

[0031] For example, FIGS. 2 through 7 and 9 illustrate various embodiments of aninner surface 112 conformingly mounted to a pressure side 22, suction side 24, andtrailing edge 28 of a rotor blade 16. FIG. 6 illustrates one embodiment of an innersurface 112 mounted to a relatively minimal portion of the pressure side 22 and thesuction side 24. FIG. 7 illustrates one embodiment of an inner surface 112 mountedto a relatively substantial portion of the suction side 24 and a relatively minimalportion of the pressure side 22. FIG. 9 illustrates another embodiment of an innersurface 112 mounted to a relatively minimal portion of the pressure side 22 and thesuction side 24.

[0032] Further, FIG. 8 illustrates one embodiment of an inner surface 112conformingly mounted to a pressure side 22 and trailing edge 28, wherein the innersurface 112 is mounted to a relatively substantial portion of the pressure side 22.

FIGS. 10 and 11 illustrate various embodiment of an inner surface 112 conforminglymounted to a pressure side 22, wherein the inner surface 112 is mounted to arelatively substantial portion of the pressure side 22.

[0033] As mentioned above, in some embodiments, the inner surface 112 may bemounted to a relatively substantial portion of the pressure side 22 and/or suction side24. This portion may be defined relative to the local chord 46. For example, the innersurface may be mounted to between approximately 20% and approximately 60%,such as between approximately 20% and approximately 50%, such as betweenapproximately 20% and approximately 40%, such as between approximately 20% andapproximately 30%, of the local chord 46 on the pressure side 22 and/or suction side24. 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 mayalso be defined relative to the local chord 46. For example, the inner surface may bemounted to between approximately 0% and approximately 20%, such as betweenapproximately 0% and approximately 15%, such as between approximately 0% andapproximately 10%, such as between approximately 0% and approximately 5%, of thelocal chord 46 on the pressure side 22 and/or suction side 24.

[0034] It should be understood that the inner surface 112 may be conforminglymounted to any one or more of the pressure side 22, the suction side 24, or the trailingedge 28, and further that the inner surface 112 may be mounted to a relativelysubstantial portion or a relatively minimal portion of any one or more of the pressureside 22, the suction side 24, or the trailing edge 28. Further, it should be understoodthat the relatively substantial portion and relatively minimal portion discussed aboveare not limited to the above disclosed ranges, and rather that any suitable range orpercentage is within the scope and spirit of the present disclosure.

[0035] As shown in FIGS. 2 through 11, the outer surface 114 of the flap 110defines a generally continuous aerodynamic surface with one or more of the exteriorsurfaces of the rotor blade 16. For example, the outer surface 114 and at least one ofthe pressure side 22 or the suction side 24 define a generally continuous aerodynamicsurface. A generally continuous aerodynamic surface is a surface that has a generallycontinuous aerodynamic contour. Thus, when two surfaces define a generallycontinuous aerodynamic surface, there is relatively little interruption in theaerodynamic contour at the intersection of the two surfaces. As shown in FIGS. 2through 7 and 9, for example, the outer surface 114 and the suction side 24 define agenerally continuous aerodynamic surface. Further, in FIGS. 2 through 11, the outersurface 114 and the pressure side 22 define a generally continuous aerodynamicsurface.

[0036] The outer surface 114 of the flap 110 may include a pressure side portion122 and/or a suction side portion 124. The pressure side portion 122 may define agenerally aerodynamic surface with the pressure side 22 of the rotor blade 16, asdiscussed above, while the suction side portion 124 may define a generallyaerodynamic surface with the suction side 24, as discussed above. In someembodiments, 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 FIG. 11.

[0037] In other embodiments, however, the outer surface 114 may further includeadditional surfaces. For example, in some embodiments, as shown in FIGS. 2 through10, the outer surface 114 may further include a planer portion 126. The planer portion126 may extend between the pressure side portion 122 and the suction side portion124, or between one of the pressure side portion 122 or suction side portion 124 andthe inner surface 112.

[0038] The planer portion 126 in exemplary embodiments extends in the generallyspan-wise direction. Thus, in some embodiments the planer portion 126 may extendgenerally parallel to the span 44 of the rotor blade 16. Alternatively, however, theplaner portion 126 may extend at any suitable angle to the span 44, as desired orrequired. In further alternative embodiments, the planer portion 126 may extend inany suitable angle relative to the rotor blade 16.

[0039] Further, as shown, the planer portion 126 in some embodiments isgenerally perpendicular to the local chord 46 of the rotor blade 16. Thus, as theplaner portion 126 extends, such as in the generally span-wise direction, the planerportion 126 at any location may be generally perpendicular to the local chord 46 atthat location. Alternatively, however, the planer portion 126 may be positioned at anysuitable angle to perpendicular, or have any other suitable angle relative to the rotorblade 16.

[0040] In some embodiments, as shown in FIGS. 2 through 10, the flap 110 mayextend in the generally chord-wise direction no further than the maximum chord 48 ofthe rotor blade 16. In these embodiments, at no location along the flap 110 in thegenerally span-wise direction does the flap 110 extend further than the maximumchord 48 of the rotor blade 16. In embodiments wherein the flap 110 includes aplaner portion 126, the planer portion 126 may extend no further than the maximumchOrd 48 of the rotor blade 16. In embodiments wherein the flap 11 only includes apressure side portion 122 and a suction side portion 124, neither the pressure sideportion 122 nor the suction side portion 124 extends any further than the maximumchord 48 of the rotor blade 16. In other embodiments, as shown in FIG. 11, however,the flap 110 may extend in the generally chord-wise direction further than the maximum chord 48 of the rotor blade 16, as desired or required. In theseembodiments, at any location along the flap 110 in the generally span-wise direction,the flap 110 may extend further than the maximum chord 48 of the rotor blade 16.

[0041] In some embodiments, as shown in FIGS. 2 through 5, the flap 110 mayhave a generally decreasing cross-sectional area in the span-wise direction towards thetip 32. Alternatively, however, the flap 110 may have a generally increasing cross-sectional area in the span-wise direction towards the tip 32, or may have a generallyconstant cross-sectional area.

[0042] The present disclosure may further be directed to a method for reducingthe separation region of a rotor blade 16 for a wind turbine 10. The method includesthe step of mounting a flap 110 to a rotor blade 16, as discussed above. The methodfurther includes rotating the rotor blade 16 on the wind turbine 10.

This written description uses examples to disclose the invention, including the bestmode, 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 incorporatedmethods. The patentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they include structural elements thatdo not differ from the literal language of the claims, or if they include equivalentstructural elements with insubstantial differences from the literal languages of theclaims.

Claims

A rotor blade assembly 100 for a wind turbine 10, wherein the rotor blade assembly 100 comprises: a rotor blade 16 having outer surfaces defining a printing side22, a suction side 24, a leading edge 26 and a trailing edge 28, each extending a general span direction between a tip 32 and a root 34, and a board area 52; and, a flap 110 in the inner plate region 52, which flaps in general span direction from the root 34 toward the tip 32, wherein the flap 110 comprises an inner surface 112 and an outer surface 114, characterized in that the inner surface 112 is consistent with tuning with mounted on only one of the printing side 22 and the suction side 24, the outer surface 114 of which one impression side 22 and the suction side 24 define general continuous aerodynamic surface.

The rotor blade assembly 100 according to claim 1, wherein the flap 110 has an generally decreasing cross-sectional area in the spanwise direction toward the tip 32.

The rotor blade assembly 100 according to any one of claims 1-2, wherein the flap 110 extends in a general chord direction but no longer a maximum chord 48 of the rotor blade 16.

Rotor blade assembly 100 according to any one of claims 1-3, wherein the outer surface 114 of the flap 110 comprises a pressure side portion 122 and one-side side portion 124.

The rotor blade assembly 100 of claim 4, wherein the outer surface 114 of the flap 110 further comprises a flat portion 126 extending the intermediate pressure side portion 122 and suction side portion 124.

The rotor blade assembly 100 of claim 5, wherein the flat portion 126 extends in the general span direction.

The rotor blade assembly 100 according to any of claims 5-6, wherein the planar portion 126 is generally perpendicular to a local chord 46 of the rotor blade 16.

The rotor blade assembly 100 according to any of claims 5-7, wherein the flat portion 126 does not extend beyond the maximum cord 48 of the rotor blade 16.

The rotor blade assembly 100 according to any one of claims 1-8, wherein the inner surface 112 is in accordance with mounted on the printing side 22.

The rotor blade assembly 100 according to any one of claims 1-8, wherein the inner surface 112 is in accordance with mounted on the suction side 24.

A rotor blade assembly 100 according to any one of claims 1-8, wherein the flap 110 extends beyond the associated trailing edge 28 in a chordal direction.

The rotor blade assembly 100 of claim 9, wherein the outer surface 114 and the pressure side 22 define a general continuous aerodynamic surface.

The rotor blade assembly 100 of claim 10, wherein the outer surface 114 and the suction side 24 define a general continuous aerodynamic surface.

A wind turbine 10 comprising: a plurality of rotor blade assemblies 100 according to any one of the preceding claims.

A method of reducing the separation area of a rotor blade 16 to a wind turbine 10, comprising: mounting a flap 110 to a rotor blade 16, wherein the rotor blade 16 has outer surfaces defining a pressure side 22, a suction side 24, a leading edge 26 and one back edge 28, each extending in a general span direction between tip 32 and a root 34, and an inner board area 52, wherein the flap 110 comprises an inner surface 112 and an outer surface 114, characterized by the inner surface 112 is in accordance with mounted on only one of the pressure side 22 and the suction side 24, the outer surface 114 and one of the impression side 22 and the suction side 24 defining general continuous aerodynamic surface; and, rotating the rotor blade 16 on the wind turbine 10.