Wind turbine rotor blade assembly having a structural trailing edge

A rotor blade assembly includes a rotor blade defining a pressure side and a suction side extending between a leading edge and a trailing edge. Further, the rotor blade assembly includes at least one structural feature secured within the rotor blade and spaced apart from the trailing edge to define a void between the pressure side, the suction side, and the trailing edge. Moreover, the rotor blade assembly includes an adhesive filling the void between the pressure side, the suction side, and the trailing edge to provide an adhesive connection between the pressure side, the suction side, the trailing edge, and the structural feature(s). In addition, the adhesive contacts the structural feature(s) at an interface and defines a fillet profile.

FIELD

The present disclosure relates in general to wind turbine rotor blades, and more particularly to a structural trailing edge for wind turbine rotor blades.

BACKGROUND

The rotor blades generally include a suction side shell and a pressure side shell typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves.

In addition, conventional rotor blades require a substantial amount of bond paste to provide structure at various blade joints (e.g. at the leading or trailing edges of the rotor blade) to prevent local buckling of the suction and pressure side shells. Due to the complex geometry near these joint areas, it is often difficult to provide this structure in other ways that would be lighter than bond paste. Thus, conventional rotor blades typically utilize excess paste for the structure needed at the joints. Such excess paste, however, is expensive, heavy, and can limit the types of adhesives that can be used. For example, heavy and thick adhesive sections containing fast curing adhesives with high exothermic reactions can generate excess heat and damage the surrounding materials, thereby creating safety hazards.

In view of the foregoing, the art is continually seeking improved structural trailing edges for wind turbine rotor blades that address the aforementioned issues.

BRIEF DESCRIPTION

In one aspect, the present disclosure is directed to a rotor blade assembly. The rotor blade assembly includes a rotor blade defining a pressure side and a suction side extending between a leading edge and a trailing edge. Further, the rotor blade assembly includes at least one structural feature secured within the rotor blade and spaced apart from the trailing edge to define a void between the pressure side, the suction side, and the trailing edge. Moreover, the rotor blade assembly includes an adhesive filling the void between the pressure side, the suction side, and the trailing edge to provide an adhesive connection between the pressure side, the suction side, the trailing edge, and the structural feature(s). In addition, the adhesive contacts the structural feature(s) at an interface and defines a fillet profile.

In one embodiment, the fillet profile may define a convex curve that faces the trailing edge of the rotor blade. In another embodiment, the adhesive completely fills the void and the convex curve.

In further embodiments, the structural feature(s) may have a tapered chord-wise cross-section that contacts the inner surfaces of the pressure and suction sides. In such embodiments, the adhesive secures the structural feature(s) within the rotor blade and to the inner surfaces of the pressure and suction sides, respectively. In additional embodiments, the structural feature(s) is constructed, at least in part, of a thermoset material or a thermoplastic material. In such embodiments, the thermoset material and/or the thermoplastic material may also be reinforced with one or more fiber materials. In particular embodiments, the structural feature(s) may be constructed, at least in part, of a core material at least partially surrounded by at least one of the thermoset material or the thermoplastic material. In such embodiments, the core material may be compressible.

In additional embodiments, the structural feature(s) may include a hollow cross-section. In another embodiment, the rotor blade assembly may also include a pressurized air source configured to pressurize the structural feature(s) between the pressure and suction sides of the rotor blade. In one embodiment, the pressurized air source may be configured to provide pressurized air, for example, within the hollow cross-section. In several embodiments, the rotor blade assembly may further include a plurality of structural features arranged in an end-to-end configuration in a chord-wise direction.

In another aspect, the present disclosure is directed to a method for joining shell members of a rotor blade together. The method includes providing a first shell member of the rotor blade. The method further includes providing at least one structural feature atop the first shell member of the rotor blade and spaced apart from a trailing edge of the rotor blade. In addition, the method includes placing a second shell member of the rotor blade atop the first shell member to form the rotor blade. As such, the rotor blade defines a void between the first shell member, the second shell member, the trailing edge, and the structural feature(s). Moreover, the method includes applying pressure to either or both of the first or second shell members to compress the structural feature(s), thereby forming a fillet profile within the void. Further, the method includes filling the void with an adhesive to provide an adhesive connection between the first shell member, the second shell member, the trailing edge, and the structural feature(s).

In one embodiment, the fillet profile may define a convex curve that faces the trailing edge of the rotor blade. In such embodiments, the step of filling the void with the adhesive may further include filling the convex curve with the adhesive. In another embodiment, the step of providing the structural feature(s) atop the first shell member of the rotor blade and spaced apart from the trailing edge may include pre-forming the structural feature(s) and securing the structural feature(s) to the first shell member. Alternatively, the step of providing the structural feature(s) atop the first shell member of the rotor blade and spaced apart from the trailing edge may include printing and depositing, via a computer numeric control (CNC) device, the structural feature(s) onto the first or second shell members of the rotor blade.

In further embodiments, the step of applying pressure to either or both of the first or second shell members to compress the structural feature(s) causes a tapered chord-wise cross-section of the structural feature(s) to contact the inner surfaces of the first and/or second shell members of the rotor blade.

In additional embodiments, the method may further include providing the adhesive between the inner surfaces of the first and second shell members of the rotor blade and the structural feature(s) to secure the structural feature(s) within the rotor blade.

In particular embodiments, the method may include forming the structural feature(s), at least in part, of a thermoset material and/or a thermoplastic material. In such embodiments, the method may also include reinforcing the thermoset material and/or the thermoplastic material with one or more fiber materials. In certain embodiments, the step of forming the structural feature(s), at least in part, of the thermoset material and/or the thermoplastic material may include at least partially surrounding a core material with at least one of the thermoset material or the thermoplastic material.

In yet another embodiment, the step of providing the structural feature(s) atop the first shell member of the rotor blade and spaced apart from the trailing edge of the rotor blade may include arranging a plurality of structural features in an end-to-end configuration in a chord-wise direction. It should be understood that the method may further include any of the additional features and/or steps as described herein.

DETAILED DESCRIPTION

Generally, the present disclosure is directed to a rotor blade assembly having an adhesive connection between the extreme trailing edge of the rotor blade and a fiber laminate connection immediately after. More particularly, the adhesive connection is made between both the pressure and suction sides of the rotor blade as well as to the fiber laminate connection at a fillet interface. Thus, the adhesive connection is configured to improve the effectiveness of the bond as it helps to form a fillet profile, which is the most robust profile in terms of crack propagation. The fiber laminate connection is made using a fiber laminate within a resin matrix, overlaid around a compressible core material, thus ensuring a strong bond and creating the preferential convex adhesive fillet profile as viewed from the trailing edge of the rotor blade.

Referring now to the drawings,FIG.1illustrates one embodiment of a wind turbine10according to the present disclosure. As shown, the wind turbine10includes a tower12with a nacelle14mounted thereon. A plurality of rotor blades16are mounted to a rotor hub18, which is in turn connected to a main flange that turns a main rotor shaft (not shown). The wind turbine power generation and control components are housed within the nacelle14. The view ofFIG.1is provided for illustrative 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 wind turbine configuration. In addition, the present invention is not limited to use with wind turbines, but may be utilized in any application having rotor blades. Further, the methods described herein may also apply to manufacturing any similar structure that benefits from printing a structure directly to skins within a mold before the skins have cooled so as to take advantage of the heat from the skins to provide adequate bonding between the printed structure and the skins. As such, the need for additional adhesive or additional curing is eliminated.

Referring now toFIGS.3-5, various views of several embodiments of one of the rotor blades16ofFIG.1(also referred to herein as rotor blade assembly) are illustrated in accordance with aspects of the present subject matter. In particular,FIG.2illustrates a perspective view of the rotor blade16.FIG.3illustrates a cross-sectional view of the rotor blade16along the sectional line3-3shown inFIG.2.FIG.4illustrates a detailed, cross-sectional view of the rotor blade16ofFIG.4.FIG.5illustrates a detailed, cross-sectional view of another embodiment of the rotor blade16according to the present disclosure.

In addition, as shown in the illustrated embodiments, the rotor blade16generally includes a blade root30configured to be mounted or otherwise secured to the hub18(FIG.1) of the wind turbine10and a blade tip32disposed opposite the blade root30. A body shell21of the rotor blade generally extends between the blade root30and the blade tip32along a longitudinal axis27. The body shell21may generally serve as the outer casing/covering of the rotor blade16and may define a substantially aerodynamic profile, such as by defining a symmetrical or cambered airfoil-shaped cross-section. The body shell21may also define a pressure side34and a suction side36extending between leading and trailing edges26,28of the rotor blade16. Further, the rotor blade16may also have a span23defining the total length between the blade root30and the blade tip32and a chord25defining the total length between the leading edge26and the trialing edge28. As is generally understood, the chord25may vary in length with respect to the span23as the rotor blade16extends from the blade root30to the blade tip32.

In several embodiments, the body shell21of the rotor blade16may be formed as a single, unitary component. Alternatively, the body shell21may be formed from a plurality of shell components. For example, the body shell21may be manufactured from a first shell half generally defining the pressure side34of the rotor blade16and a second shell half generally defining the suction side36of the rotor blade16, with such shell halves being secured to one another at the leading and trailing ends26,28of the blade16.

Additionally, the body shell21may generally be formed from any suitable material. For instance, in one embodiment, the body shell21may be formed entirely from a laminate composite material, such as a carbon fiber reinforced laminate composite or a glass fiber reinforced laminate composite. Alternatively, one or more portions of the body shell21may be configured as a layered construction and may include a core material, formed from a lightweight material such as wood (e.g., balsa), foam (e.g., extruded polystyrene foam) or a combination of such materials, disposed between layers of laminate composite material. In addition, the body shell21may be constructed, at least in part, from a thermoset and/or a thermoplastic material.

The thermoplastic materials described herein generally encompass a plastic material or polymer that is reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and returns to a more rigid state upon cooling. Further, thermoplastic materials may include amorphous thermoplastic materials and/or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials may generally include, but are not limited to, styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones, and/or imides. More specifically, exemplary amorphous thermoplastic materials may include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chlorides (PVC), polyvinylidene chloride, polyurethane, or any other suitable amorphous thermoplastic material. In addition, exemplary semi-crystalline thermoplastic materials may generally include, but are not limited to polyolefins, polyamides, fluropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and/or acetals. More specifically, exemplary semi-crystalline thermoplastic materials may include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene, polyamide (nylon), polyetherketone, or any other suitable semi-crystalline thermoplastic material.

Further, the thermoset materials described herein generally encompass a plastic material or polymer that is non-reversible in nature. For example, thermoset materials, once cured, cannot be easily remolded or returned to a liquid state. As such, after initial forming, thermoset materials are generally resistant to heat, corrosion, and/or creep. Example thermoset materials may generally include, but are not limited to, some polyesters, some polyurethanes, esters, epoxies, or any other suitable thermoset material.

In addition, as mentioned, the thermoplastic and/or the thermoset material described herein may optionally be reinforced with a fiber material, including but not limited to glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or similar or combinations thereof. In addition, the direction of the fibers may include multi-axial, unidirectional, biaxial, triaxial, or any other another suitable direction and/or combinations thereof. Further, the fiber content may vary depending on the desired stiffness, and/or the location within the rotor blade16.

Referring particularly toFIG.3, the rotor blade16may also include one or more longitudinally extending structural components configured to provide increased stiffness, buckling resistance, and/or strength to the rotor blade16. For example, the rotor blade16may include one or more longitudinally extending spar caps20,22configured to be engaged against the opposing inner surfaces35,37of the pressure and suction sides34,36of the rotor blade16, respectively. Additionally, one or more shear webs24may be disposed between the spar caps20,22so as to form a beam-like configuration. The spar caps20,22may generally be designed to control the bending stresses and/or other loads acting on the rotor blade16in a generally span-wise direction (a direction parallel to the span23of the rotor blade16) during operation of a wind turbine10. Similarly, the spar caps20,22may also be designed to withstand the span-wise compression occurring during operation of the wind turbine10.

The spar caps20,22and/or the shear web(s)24described herein may also be formed of one or more thermoset and/or thermoplastic materials as well as one or more pultrusions. As used herein, “pultrusions” or similar generally encompass reinforced materials (e.g. fibers or woven or braided strands) that are impregnated with a resin and pulled through a stationary die such that the resin cures or undergoes polymerization. As such, the process of manufacturing pultruded members is typically characterized by a continuous process of composite materials that produces composite parts having a constant cross-section. Thus, the pre-cured composite materials may include pultrusions constructed of reinforced thermoset or thermoplastic materials. Further, the spar caps20,22, may be formed of the same pre-cured composites or different pre-cured composites. In addition, the pultruded components may be produced from rovings, which generally encompass long and narrow bundles of fibers that are not combined until joined by a cured resin.

Referring particularly toFIGS.3-5, the rotor blade assembly16further includes at least one structural feature38,40secured within the rotor blade16at the trailing edge28. For example, as shown in the illustrated embodiments, the rotor blade assembly16may include a plurality of structural features38,40arranged in an end-to-end configuration (i.e. abutting against each other) in a chord-wise direction. More specifically, as shown, the rotor blade assembly16includes two structural features, namely, a first structural feature38closest to the trailing edge28and a second structural feature40closest to the leading edge26. It should be understood that the rotor blade assembly16may further include any suitable number of structural features including less than two and more than two. In further embodiments, as shown, the structural feature(s)38,40may be formed of a compressible material. As such, when the structural feature(s)38,40are compressed between the pressure and section sides34,36of the rotor blade, the structural feature(s)38,40have a tapered chord-wise cross-section that contacts the inner surfaces35,37of the pressure and suction sides34,36. In addition, as shown particularly inFIGS.3and4, the structural feature(s)38,40may have a hollow cross-section. In such embodiments, the rotor blade assembly may also include a pressurized air source50configured to pressurize the structural feature(s)38,40between the pressure and suction sides34,36. In one embodiment, for example, the pressurized air source50may be configured to provide pressurized air within the hollow cross-section. Alternatively, as shown inFIG.5, the structural feature(s)38,40may have a solid cross-section.

In additional embodiments, the structural feature(s)38,40may be constructed, at least in part, of a thermoset material or a thermoplastic material, such as the thermoset and/or thermoplastic materials described herein. In such embodiments, the thermoplastic and/or the thermoset material as described herein may optionally be reinforced with one or more fiber materials, including but not limited to glass fibers, carbon fibers, polymer fibers, wood fibers, bamboo fibers, ceramic fibers, nanofibers, metal fibers, or similar or combinations thereof. In addition, the direction of the fibers may include multi-axial, unidirectional, biaxial, triaxial, or any other another suitable direction and/or combinations thereof. Further, the fiber content may vary depending on the desired stiffness. More specifically, in particular embodiments, the structural feature(s)38,40may be constructed of a compressible core material that is partially surrounded by a thermoset material and/or a thermoplastic material.

Further, as shown inFIGS.3-5, the structural feature(s)38,40are also spaced apart from the trailing edge28by a predetermined chord-wise distance to define a minimal void42between the pressure side34, the suction side36, and the trailing edge28. Thus, as shown, the rotor blade assembly16also includes an adhesive44that fills (usually completely) the void42so as to provide an adhesive connection between the pressure side34, the suction side36, the trailing edge28, and the structural feature(s)38,40. In addition, as shown, the adhesive44contacts at least one of the structural feature(s)38,40at an interface46that defines a fillet or curved profile. More specifically, as shown, the fillet profile46defines a convex curve48that faces the trailing edge28of the rotor blade16. Thus, the adhesive quantity can be controlled in terms of parasitic mass squeeze out via the compressible material which acts as a barrier for excess adhesive that leaks into the blade cavity. In additional embodiments, the adhesive44can also be configured to secure the structural feature(s) within the rotor blade16and to the inner surfaces35,37of the pressure and suction sides34,36, respectively.

Referring now toFIG.6, a flow diagram of one embodiment of a method100joining shell members of a rotor blade together is illustrated. In general, the method100will be described herein with reference to the rotor blade16described above with reference toFIGS.1-5. However, it should be appreciated by those of ordinary skill in the art that the disclosed method100may generally be utilized to manufacture any other rotor blade having any suitable configuration. In addition, althoughFIG.6depicts steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, and/or adapted in various ways without deviating from the scope of the present disclosure.

As shown at102, the method100includes providing a first shell member of the rotor blade16. In certain embodiments, the shell members described herein (which form the pressure and/or suction side surfaces34,36) may include one or more continuous, multi-axial (e.g. biaxial) fiber-reinforced thermoplastic or thermoset outer skins. Further, in particular embodiments, the shell members may be formed using injection molding, 3-D printing, 2-D pultrusion, 3-D pultrusion, thermoforming, vacuum forming, pressure forming, bladder forming, automated fiber deposition, automated fiber tape deposition, and/or vacuum infusion.

As shown at104, the method100includes providing at least one structural feature38,40atop the first shell member of the rotor blade16and spaced apart from the trailing edge28of the rotor blade16. For example, as shown at105, the method100may include pre-forming the structural feature(s)38,40and securing the structural feature(s)38,40to the first shell member. Alternatively, as shown at107, the method100may include printing and depositing, e.g. via a computer numeric control (CNC) device, the structural feature(s)38,40onto the first or second shell members of the rotor blade16. As used herein, 3-D printing is generally understood to encompass processes used to synthesize three-dimensional objects in which successive layers of material are formed under computer control to create the objects. As such, objects of almost any size and/or shape can be produced from digital model data. It should further be understood that the methods of the present disclosure are not limited to 3-D printing, but rather, may also encompass more than three degrees of freedom such that the printing techniques are not limited to printing stacked two-dimensional layers, but are also capable of printing curved shapes.

Still referring toFIG.6, as shown at106, the method100includes placing a second shell member of the rotor blade16atop the first shell member to form the rotor blade16. Thus, as mentioned, the rotor blade16defines a void42between the first shell member, the second shell member, the trailing edge28, and at least one of the structural feature(s)38,40. As shown at108, the method100includes applying pressure to either or both of the first or second shell members to compress the structural feature(s)38,40, thereby forming a fillet profile48within the void42. In one embodiment, the step of applying pressure to either or both of the first or second shell members to compress the structural feature(s)38,40causes a tapered chord-wise cross-section of the structural feature(s)38,40to contact the inner surfaces35,37of the first and/or second shell members of the rotor blade16.

As shown at110, the method100includes filling the void42with an adhesive44to provide an adhesive connection between the first shell member, the second shell member, the trailing edge28, and the structural feature(s)38,40. More specifically, in one embodiment, the convex curve48within the void42may be filled with the adhesive44. In additional embodiments, the method100may further include providing the adhesive44between the inner surfaces35,37of the first and second shell members of the rotor blade16and the structural feature(s)38,40to secure the structural feature(s)38,40within the rotor blade16.