Method of joining wind turbine rotor blade segments via structural members

A method for joining rotor blade segments of a rotor blade includes forming a female structural member having a receipt portion with a cavity and a structural portion. Further, the method includes securing the female structural member within a first blade segment. The method also includes forming a male structural member having a protrusion portion and a structural portion. Moreover, the method includes securing the structural portion of the male structural member within a second blade segment. In addition, the method includes inserting the protrusion portion into the cavity. As such, when inserted, an interface of the protrusion portion and the cavity forms one or more internal channels. Thus, the method further includes injecting adhesive into the one or more internal channels so as to secure the first and second blade segments together.

FIELD

The present subject matter relates generally to wind turbines, and more particularly to segmented rotor blades for wind turbines and methods of joining same.

BACKGROUND

The construction of a modern rotor blade generally includes skin or shell components, opposing spar caps, and one or more shear webs extending between the opposing spar caps. The skin is typically manufactured from layers of fiber composite and a lightweight core material and forms the exterior aerodynamic airfoil shape of the rotor blade. Further, the spar caps provide increased rotor blade strength by providing structural elements along the span of the rotor blade on both interior sides of the rotor blade. Moreover, spar caps are typically constructed from glass fiber reinforced composites, though spar caps for some larger blades may be constructed from carbon fiber reinforced composites. The shear web(s) generally include structural beam-like components that extend essentially perpendicular between the opposing spar caps and across the interior portion of the rotor blade between the outer skins.

The size, shape, and/or weight of rotor blades are factors that contribute to energy efficiencies of wind turbines. An increase in rotor blade size increases the energy production of a wind turbine, while a decrease in weight also furthers the efficiency of a wind turbine. Furthermore, as the size of wind turbines increases, particularly the size of the rotor blades, so do the respective costs of manufacturing, transporting, and assembly of the wind turbines. The economic benefits of increased wind turbine sizes must be weighed against these factors.

One known strategy for reducing the costs of pre-forming, transporting, and erecting wind turbines having rotor blades of increasing sizes is to manufacture the rotor blades in blade segments. As such, the blade segments may be assembled to form the rotor blade after, for example, the individual blade segments are transported to an erection location. For example, some rotor blades include either bonded or bolted joints.

However, certain adhesive bonds provide additional challenges. For example, the internal consolidation pressure required to obtain an effective bond can be difficult to achieve and maintain during the bond process. Of particular concern is the internal consolidation pressure in areas of the turbine blade that are inaccessible. For instance, the portion of the rotor blade at the tip is often smaller and cannot be easily reached using conventional methods. The internal consolidation pressure necessary at these inaccessible areas is generally referred to as blind pressure. In addition, wet adhesives can be difficult to apply without air bubbles and/or may provide uneven coverage with slide-in assemblies. Additionally, adhesive squeeze-out can cause parasitic weight, undesirable spills, a subpar bond, and/or undesirable clean-up. Further, the ability to reposition the surfaces can be limited due to the risk of introducing air and/or air pockets in the adhesive.

As such, the art is continuously seeking new and improved joint technologies for joining blade segments of rotor blades. Accordingly, the present disclosure is directed to a rotor blade assembly that guides/self-aligns, controls accuracy, and simplifies the structural bond between two blade segments by the ability to dry-assemble the interlocking pieces and inject the adhesive in-situ.

BRIEF DESCRIPTION

In one aspect, the present disclosure is directed to a method for joining rotor blade segments of a rotor blade. The method includes forming a female structural member having a receipt portion and a structural portion, the receipt portion defining a cavity. Further, the method includes securing the female structural member within a first blade segment. The method also includes forming a male structural member having a protrusion portion and a structural portion. Moreover, the method includes securing the structural portion of the male structural member within a second blade segment. In addition, the method includes inserting the protrusion portion of the male structural member into the cavity of the female structural member. As such, when inserted, an interface of the protrusion portion of the male structural member and the cavity of the female structural member forms one or more internal channels. Thus, the method further includes injecting adhesive into the one or more internal channels so as to secure the first and second blade segments together.

In one embodiment, the method may further include forming either or both of the female structural member or the male structural member with one or more bulkheads. For example, in certain embodiments, the method may include forming the female structural member with a first end bulkhead and a second end bulkhead.

In additional embodiments, the female and male structural members may each include a divider bulkhead positioned between the receipt portion and the structural portion of the female structural member and the protrusion portion and the structural portion of the male structural member, respectively. In such embodiments, the method may include inserting the protrusion portion of the male structural member into the cavity of the female structural member until the divider bulkhead of the male structural member abuts against the first end bulkhead of the female structural member at a bulkhead joint. In further embodiments, the bulkhead(s) may be sized to abut against an internal wall of one of the rotor blade segments of the rotor blade.

In several embodiments, the method may include injecting the adhesive into the one or more internal channels from an exterior location of the rotor blade through the one or more bulkheads. In such embodiments, the method may also include filling the one or more internal channels with the adhesive and allowing the adhesive to fill the bulkhead joint via one or more controlled blow holes.

In further embodiments, the structural portions of the female and male structural members may include one or more spar caps and/or at least one shear web. In such embodiments, the method may include forming one or more spar caps into the cavity and the protrusion portion of the female and male structural members, respectively. As such, when the protrusion portion is inserted into the cavity, the spar cap(s) of the cavity and the spar cap(s) of the protrusion portion are configured to align in a span-wise direction.

In another aspect, the present disclosure is directed to a segmented rotor blade assembly for a wind turbine. The rotor blade assembly includes a first blade segment comprising a female structural member having a receipt portion and a structural portion. The receipt portion defines a cavity. The rotor blade assembly also includes a second blade segment having a male structural member with a protrusion portion and a structural portion. The protrusion portion of the male structural member is received within the cavity of the female structural member. Further, when inserted, an interface of the protrusion portion of the male structural member and the cavity of the female structural member forms one or more internal channels. The rotor blade assembly further includes an adhesive within and limited to the one or more internal channels that secures the first and second blade segments together. It should be understood that the rotor blade assembly may further include any of the additional features described herein.

In addition, in one embodiment, a cross-sectional shape of the cavity of the female structural member substantially corresponds to a cross-sectional shape of the protrusion portion of the male structural member. In another embodiment, the cross-sectional shapes of the cavity and the protrusion portion tapers from a first end to a second end, respectively. More specifically, in particular embodiments, the cross-sectional shapes of the cavity and the protrusion portion may be a trapezoid.

DETAILED DESCRIPTION

Generally, the present disclosure is directed to a segmented rotor blade for a wind turbine and methods of joining same. For example, in one embodiment, the method includes forming a female structural member having a receipt portion with a cavity and a structural portion. Further, the method includes securing the female structural member within a first blade segment. The method also includes forming a male structural member having a protrusion portion and a structural portion. Moreover, the method includes securing the structural portion of the male structural member within a second blade segment. In addition, the method includes inserting the protrusion portion into the cavity. As such, when inserted, an interface of the protrusion portion and the cavity forms one or more internal channels. Thus, the method further includes injecting adhesive into the one or more internal channels so as to secure the first and second blade segments together. Accordingly, a critical blind bond in the joint connection is avoided by having a secondary structure (i.e. the female and male structural members) bonded onto a primary structure (i.e. the first and second blade segments) where the continuation of the stress member is paramount.

The present disclosure provides many advantages not present in the prior art. For example, the method of the present disclosure provides a closed and controlled adhesive layer gap to be fed externally via channel(s) at the interface of the female and male structural members (e.g. boxes). Further, the male and female boxes may also provide fibrous composite and adhesion to the ends of the spar beam connection that is prone to strain to first crack of peel degradation, i.e. an anti-peel layer. In addition, the entire bonding operation is completed blind or within an internal structure or cavity. As such, the containment of the bonded area eliminates spill and/or parasitic weight of the rotor blade. Accordingly, the final assembly provides a controlled and even stress path, limits the changes in the bending moment of the rotor blade, and lowers additional weight of other conventional methods.

Referring now to the drawings,FIG.1illustrates a perspective view of 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.

Referring now toFIG.2, a perspective view of one embodiment of one of the rotor blades16of the wind turbine10ofFIG.1according to the present disclosure is shown. As shown, the rotor blade16may include a plurality of individual blade segments20aligned in an end-to-end configuration from a blade tip22to a blade root24. Further, as shown, each of the individual blade segments20may be uniquely configured so that the plurality of blade segments20define a complete rotor blade16having a designed aerodynamic profile, length, and other desired characteristics. For example, each of the blade segments20may have an aerodynamic contour that corresponds to the aerodynamic contour of adjacent blade segments20. Thus, the aerodynamic contours of the blade segments20may form a continuous aerodynamic contour of the rotor blade16. As such, the rotor blade16may include any suitable number of segments20. For example, as shown, the rotor blade16includes three rotor blade segments20. It should be understood, however, that the rotor blade16may have any suitable number of blade segments20, such as less than three or more than three, such as four or more.

In general, the rotor blade16, and thus each blade segment20, may include a pressure side32and a suction side34extending between a leading edge36and a trailing edge38. Additionally, the rotor blade16may have a span44extending along a span-wise axis46and a chord48extending along a chord-wise axis50. Further, as shown, the chord48may change throughout the span44of the rotor blade16. Thus, a local chord may be defined at any span-wise location on the rotor blade16or any blade segment20thereof.

The rotor blade16may, in exemplary embodiments, be curved. Curving of the rotor blade16may entail bending the rotor blade16in a generally flapwise direction and/or in a generally edgewise direction. The flapwise direction is a direction substantially perpendicular to a transverse axis through a cross-section of the widest side of the rotor blade16. Alternatively, the flapwise direction may be construed as the direction (or the opposite direction) in which the aerodynamic lift acts on the rotor blade16. The edgewise direction is perpendicular to the flapwise direction. Flapwise curvature of the rotor blade16is also known as pre-bend, while edgewise curvature is also known as sweep. Thus, a curved rotor blade16may be pre-bent and/or swept. Curving may enable the rotor blade16to better withstand flapwise and edgewise loads during operation of the wind turbine10, and may further provide clearance for the rotor blade16from the tower12during operation of the wind turbine10.

Referring now toFIGS.3-8, various views of the blade segment(s)20and components thereof according to the present disclosure are illustrated. In particular,FIG.3illustrates a perspective, internal view of one embodiment of a first blade segment26having a female structural member40secured therein.FIGS.4and5illustrate various views of the female structural member40according to the present disclosure.FIG.6illustrates a perspective, internal view of one embodiment of a second blade segment28having a male structural member42secured therein.FIGS.7and8illustrate various views of the male structural member42according to the present disclosure.

Referring particularly toFIGS.3and5, the female structural member40may have a receipt portion52and a structural portion54. Further, as shown, the receipt portion52defines a cavity56or box that is closed from all ends except its inlet, which is configured to receive the male structural member42. For example, as shown particularly inFIGS.3and5, the cross-sectional shape of the cavity56may taper from a first end62to a second end64. More specifically, in particular embodiments, the cross-sectional shape of the cavity56may be a square, a rectangle, a trapezoid, or any other suitable cross-section shape. For example, as shown inFIG.4, the cross-sectional shape of the cavity56may be a square.

Moreover, as shown, the structural portion54of the female structural member40may include one or more spar caps55and/or at least one shear web57arranged between the spar caps55. In addition, as shown, the cavity56of the female structural member40may also include one or more spar caps59formed into a side wall thereof. Thus, as shown, the spar caps55of the structural portion54and the spar caps59of the cavity are substantially aligned in a span-wise direction to form a continuous spar cap.

In addition, as shown inFIGS.3and5, the female structural member40may be formed with one or more bulkheads66. For example, as shown inFIG.3, the female structural member40may a first end bulkhead68and a divider bulkhead70. More specifically, as shown, the divider bulkhead70may be positioned between the receipt portion52and the structural portion54of the female structural member40. In addition, as shown inFIG.5, the female structural member40may also include a second end bulkhead72. It should be further understood that the female and male structural members40,42may further includes any number of bulkheads at any suitable location along their lengths.

Referring now toFIGS.6and8, the male structural member42may include a protrusion portion58and a structural portion60. Thus, as shown inFIGS.9-11, the protrusion portion58of the male structural member42is sized to be received within the cavity56of the female structural member40. In further embodiments, the structural portion60of the male structural member42may include one or more spar caps65and/or at least one shear web67. In addition, the protrusion portion58of the male structural member42may also include one or more spar caps69formed therein. As such, when the protrusion portion58is inserted into the cavity56, the spar cap(s)59of the cavity56and the spar cap(s)69of the protrusion portion58are configured to align in a span-wise direction. In addition, as shown, a cross-sectional shape of the cavity56of the female structural member40substantially corresponds to a cross-sectional shape of the protrusion portion58of the male structural member42such that the protrusion portion58fits easily within the cavity56, e.g. via a dry fit. For example, as shown particularly inFIGS.6and8, the cross-sectional shape of the protrusion portion58may taper from a first end74to a second end76. More specifically, in particular embodiments, the cross-sectional shape of the protrusion portion58may be a square, a rectangle, a trapezoid, or any other suitable cross-section shape. For example, as shown inFIG.7, the cross-sectional shape of the protrusion portion58may be a square.

Like the female structural member40, the male structural member42may also include one or more bulkheads78. For example, as shown particularly inFIGS.6and8, the male structural member42may also include a divider bulkhead80positioned between the protrusion portion58and the structural portion60of the male structural member42. Thus, as shown inFIGS.9-11, the protrusion portion58of the male structural member42can be inserted into the cavity56of the female structural member40, e.g. until the divider bulkhead80of the male structural member42abuts against the first end bulkhead68of the female structural member40at a bulkhead joint82. In addition, in further embodiments, the bulkhead(s)66,78described herein may be sized to abut against an internal wall of one of the rotor blade segments26,28of the rotor blade16.

Referring now toFIGS.11and12, when the protrusion portion58of the male structural member42is inserted into the cavity56of the female structural member40, one or more internal channels84are formed at an interface between the structural members40. In addition, as shown particularly inFIG.11, one or more adhesive injection channels87are formed when the female and male structural members40,42are formed.

Thus, once the protrusion portion58of the male structural member42is inserted into the cavity56of the female structural member40, the first and second blade segments26,28can be secured together by injecting an adhesive86into the one or more internal channels84, as shown atFIG.13. For example, as shown particularly inFIG.13, the adhesive86may be injected from an exterior location of the rotor blade16through the divider bulkhead70of the female structural member40. Thus, as shown inFIG.14, the adhesive86flows through and fills the internal channel(s)84and is limited by the channel(s)84(i.e. the adhesive86does not overflow to other areas of the rotor blade16). Further, as shown inFIG.15, the adhesive86can also fill the bulkhead joint82via one or more controlled blow holes88so as to further secure the joint together.

Referring now toFIG.16, a flow diagram of one embodiment of a method100for joining rotor blade segments20of the rotor blade16is illustrated. In general, the method100will be described herein with reference to the wind turbine10and rotor blade16shown inFIGS.1-15. However, it should be appreciated that the disclosed method100may be implemented with any wind turbine having any other suitable configurations. In addition, althoughFIG.16depicts 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 forming the female structural member40that includes the receipt portion52defining internal cavity56and the structural portion54. For example, in one embodiment, the female structural member40may be formed using any suitable manufacturing methods and materials, including but not limited to injection molding, 3-D printing, 2-D pultrusion, 3-D pultrusion, thermoforming, vacuum forming, pressure forming, bladder forming, and/or vacuum infusion. Suitable materials may include, for example, thermoplastic and/or thermoset materials optionally reinforced with one or more fiber materials and/or pultrusions.

As shown at104, the method100further includes securing the female structural member40within the first blade segment26. For example, in one embodiment, the female structural member40may be secured to the first blade segment26via bonding, welding, and/or mechanical fasteners. As shown at106, the method100also includes forming the male structural member42that includes the protrusion portion58and the structural portion60. For example, like the female structural member40embodiment, the male structural member42may be formed using any suitable manufacturing methods and materials, including but not limited to injection molding, 3-D printing, 2-D pultrusion, 3-D pultrusion, thermoforming, vacuum forming, pressure forming, bladder forming, and/or vacuum infusion. In addition, as mentioned, suitable materials may include, for example, thermoplastic and/or thermoset materials optionally reinforced with one or more fiber materials and/or pultrusions.

Still referring toFIG.13, as shown at108, the method100includes securing the structural portion60of the male structural member42within the second blade segment28. For example, in one embodiment, the male structural member42may be secured to the second blade segment28via bonding, welding, and/or mechanical fasteners. As shown at110, the method100also includes inserting the protrusion portion58of the male structural member42into the cavity56of the female structural member40. As such, when inserted, an interface of the protrusion portion58of the male structural member42and the cavity56of the female structural member40forms one or more internal channels84. Thus, as shown at112, the method100further includes injecting the adhesive86into the internal channel(s)84so as to secure the first and second blade segments26,28together. In addition, the female and/or male structural members40,42may also include internal and/or external electronic and/or non-electronic elements embedded therein so as to assist with curing the adhesives described herein. As such, the female and male structural members40,42may be joined via heat (electronically or conductively-induced), contact, or chemical cross-linking or curing.

Accordingly, the method100of the present disclosure provides a closed and controlled adhesive layer gap to be fed externally or internally via the internal channel(s)84. In addition, the female and male structural members40,42also provide fibrous composite and adhesion to the ends of the spar beam connection prone to strain to first crack of peel degradation, i.e. an anti-peel layer. Further, as illustrated in the various figures, the entire bonding operation can be done blind or within the internal structure/cavity56, thereby eliminating spills and/or parasitic weight.