DK202200712A1 - Modular wind turbine blade - Google Patents
Modular wind turbine blade Download PDFInfo
- Publication number
- DK202200712A1 DK202200712A1 DKPA202200712A DKPA202200712A DK202200712A1 DK 202200712 A1 DK202200712 A1 DK 202200712A1 DK PA202200712 A DKPA202200712 A DK PA202200712A DK PA202200712 A DKPA202200712 A DK PA202200712A DK 202200712 A1 DK202200712 A1 DK 202200712A1
- Authority
- DK
- Denmark
- Prior art keywords
- electrically
- scarfed
- conductive
- conductive elements
- scarfed surface
- Prior art date
Links
- 239000012790 adhesive layer Substances 0.000 claims abstract description 87
- 210000001503 joint Anatomy 0.000 claims abstract description 70
- 239000004020 conductor Substances 0.000 claims abstract description 15
- 239000002657 fibrous material Substances 0.000 claims description 68
- 239000000853 adhesive Substances 0.000 claims description 50
- 230000001070 adhesive effect Effects 0.000 claims description 50
- 239000010410 layer Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 19
- 239000000835 fiber Substances 0.000 description 28
- 229910052799 carbon Inorganic materials 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 11
- 229920005989 resin Polymers 0.000 description 11
- 239000011347 resin Substances 0.000 description 11
- 229920002430 Fibre-reinforced plastic Polymers 0.000 description 3
- 239000011151 fibre-reinforced plastic Substances 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 229920006332 epoxy adhesive Polymers 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000037452 priming Effects 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor
- F03D1/06—Rotors
- F03D1/065—Rotors characterised by their construction elements
- F03D1/0675—Rotors characterised by their construction elements of the blades
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2240/00—Components
- F05B2240/20—Rotors
- F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
- F05B2240/302—Segmented or sectional blades
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Wind Motors (AREA)
Abstract
According to the present invention there is provided a modular wind turbine blade comprising a first blade module and a second blade module connectable together to form at least part of the modular wind turbine blade. The first blade module comprises a first spar cap having a tapered end portion defining a first scarfed surface. The second blade module comprises a second spar cap. The first and second spar caps comprise an electrically-conductive material. The modular wind turbine blade further comprises an elongate connecting element for connecting the first and second blade modules. The elongate connecting element is either a) an end portion of the second spar cap, or b) a separate spar component connected to the second spar cap. The connecting element comprises an electrically-conductive material and has a tapered end portion defining a second scarfed surface configured for connection to the first scarfed surface of the first spar cap. The first and second spar caps are connected via a scarf joint comprising an adhesive layer between the first scarfed surface and the second scarfed surface. The scarf joint further comprises electrically-conductive elements in the adhesive layer and in electrical contact with both the first scarfed surface and the second scarfed surface such that the electrically-conductive elements form an electrically-conductive bridge through the adhesive layer.
Description
DK 2022 00712 A1 1
Modular wind turbine blade
The present invention relates generally to modular wind turbine blades and more specifically to a modular wind turbine blade comprising a first blade module connected to a second blade module via an improved joint.
There is a continuing desire to generate increased levels of power from onshore and offshore wind farms. One way to achieve this is to provide modern wind turbines with larger — wind turbine blades to increase the swept area of the rotor such that the wind turbine captures more energy from the wind. A wind turbine blade may be designed as a modular assembly formed of two or more blade modules to facilitate transport of the components.
The blade modules may then be connected together at the wind farm site to form the blade.
Modern wind turbine blades typically include a reinforcing spar structure to provide — structural support to an outer shell of the blade. A spar structure typically comprises longitudinally-extending spar caps that absorb bending loads experienced by the blade in use. Spar caps of adjacent blade modules may be connected to transfer loads across the interface between the blade modules. The connection between load-bearing spar components, such as spar caps, must be configured to safely transfer the high bending loads experienced by the modular wind turbine blade in use. For example, corresponding spar caps of adjacent blade modules may be bonded together with adhesive. Connecting the spar caps using adhesive helps to minimise stress concentrations in the joint.
However, in some examples, the spar caps may comprise an electrically-conductive material, such as carbon fibre. In examples where the spar caps are bonded together, the adhesive may electrically-insulate the interfacing ends of the spar caps. As such, electrical current conducted by the spar caps in the event of a lightning strike is forced to circumvent the electrically-insulating adhesive. This can cause flashovers, or electrical arcs, across the joint from one spar cap to the other. Such electrical arcs could cause damage to the modular wind turbine blade. tis against this background that the present invention has been developed.
DK 2022 00712 A1 2
According to the present invention there is provided a modular wind turbine blade comprising a first blade module and a second blade module connectable together to form at least part of the modular wind turbine blade. The first blade module comprises a first spar cap having a tapered end portion defining a first scarfed surface. The second blade module comprises a second spar cap. The first and second spar caps comprise an electrically-conductive material. The modular wind turbine blade further comprises an elongate connecting element for connecting the first and second blade modules. The elongate connecting element is either a) an end portion of the second spar cap, or b) a separate spar component connected to the second spar cap. The connecting element comprises an electrically-conductive material and has a tapered end portion defining a second scarfed surface configured for connection to the first scarfed surface of the first spar cap. The first and second spar caps are connected via a scarf joint comprising an adhesive layer between the first scarfed surface and the second scarfed surface. The scarf joint further comprises electrically-conductive elements in the adhesive layer and in electrical contact with both the first scarfed surface and the second scarfed surface such that the electrically-conductive elements form an electrically-conductive bridge through the adhesive layer.
The electrically-conductive elements may be in direct electrical contact with the first and second scarfed surfaces. Alternatively, the electrically-conductive elements may be in direct electrical contact with one of the scarfed surfaces and in indirect electrical contact with the other scarfed surface via another electrically-conductive component. In other examples the electrically-conductive elements may be in indirect electrical contact with one of the scarfed surfaces via an electrically-conductive component, and may be in indirect electrical contact with the other scarfed surface via another electrically-conductive component. In each example, the electrically-conductive elements advantageously facilitate the safe conduction of electrical current through the adhesive layer.
The electrically-conductive bridge provided by the electrically-conductive elements helps to avoid or minimise the risk of flashovers, i.e. electrical arcs, between the first spar cap and the connecting element is use. Without the electrically-conductive elements, the adhesive layer in the scarf joint may provide an electrically-insulating barrier between the first spar cap and the connecting element, and a lightning strike could cause an electrical flashover whereby an electrical current jumps, or arcs, between the first spar cap and the connecting element. The electrically-conductive elements in the adhesive layer provide a
DK 2022 00712 A1 3 safe path to conduct the electrical current through the adhesive layer, thereby minimising the risk of potentially damaging electrical flashovers.
In some examples, the electrically-conductive elements may comprise electrically- conductive fibres. For example, the electrically-conductive fibres may comprise short chopped fibres that may be between 1 mm and 5 mm in length. Preferably at least some of the electrically-conductive fibres have a length that is greater than the thickness of the adhesive layer to provide an electrically-conductive bridge through the adhesive layer. The electrically-conductive elements preferably comprise carbon fibres, i.e. the electrically- conductive fibres may be carbon fibres.
In some examples, the electrically-conductive elements may comprise electrically- conductive fibre tows, such as carbon fibre tows. For example, the electrically-conductive elements may comprise a first layer of unidirectional electrically-conductive fibre tows. The electrically-conductive elements may further comprise a second layer of unidirectional — electrically-conductive fibre tows in electrical contact with the first layer of fibre tows and oriented transverse to the first layer. In such a configuration, the combined thickness of the electrically-conductive elements will be greater in regions where tows of the first and second layers of tows overlap. The combined thickness of the overlapping fibre tows is preferably substantially equal to the thickness of the adhesive layer. This helps to ensure that the fibre tows provide an electrically-conductive bridge through the adhesive layer.
In some examples, the electrically-conductive elements may comprise a layer of woven electrically-conductive fibres. For example, the electrically-conductive fibres may be woven to form a mesh. Alternatively, the electrically-conductive fibres may be woven to form a plain weave. As such, the electrically-conductive fibres may form a fibrous fabric that is arranged in the adhesive layer. Providing electrically-conductive fibres as a layer of woven fibres may facilitate simpler assembly of the modular wind turbine blade and may help to maintain the position of the electrically-conductive fibres relative to one another during assembly.
In some examples, the modular wind turbine blade may comprise a combination of different electrically-conductive elements in the adhesive layer. For example, the scarf joint may comprise short chopped fibres in the adhesive layer as well as one or more other electrically-conductive elements as described herein. In some examples, the modular wind turbine blade may therefore comprise short chopped fibres and fibre tows or woven fibres
DK 2022 00712 A1 4 in the adhesive layer. The combination of different types of conductive elements in the adhesive layer may advantageously provide an increased number of electrically- conductive bridges through the adhesive layer.
In some examples, excess adhesive, i.e. more adhesive than actually required, may be provided to form the adhesive layer. This may help to ensure that a thorough bond is achieved between the first and second scarfed surfaces. When assembling the modular wind turbine blade, the first and second scarfed surfaces may be brought together to form the scarf joint, and the excess adhesive may be squeezed out of the scarf joint. The combination of short chopped conductive fibres with fibre tows and/or woven fibres in the adhesive layer may be advantageous because such fibre tows and/or woven fibres may help to retain the short chopped fibres, whilst facilitating drainage of excess adhesive, when the scarfed surfaces are arranged to form the scarf joint.
In some examples, the electrically-conductive elements may have an undulating profile.
Examples of an undulating profile include a zig-zag profile, i.e. an abruptly undulating profile, and a sinusoidal profile, i.e. a rounded undulating profile, amongst others. In each example, an electrically conductive element having an undulating profile preferably comprises a plurality of sections proximal to a scarfed surface, and a plurality of other sections proximal to the other scarfed surface or another electrically conductive component in the scarf joint. As such, an undulating profile may be described as an alternating profile that alternates between proximity to one scarfed surface and proximity to the other scarfed surface. An electrically-conductive element having an undulating profile may therefore extend through the adhesive layer in a plurality of locations. As will be described later, in some preferred examples an electrically-conductive element having an undulating profile may be compressed between the first and second scarfed surfaces when assembling the modular wind turbine blade.
In some other examples, the electrically-conductive elements may comprise one or more individual blocks, i.e. bodies, of electrically-conductive material. Such electrically- conductive elements may be easier and/or faster to arrange in the adhesive layer and may have a lower electrical resistance for conducting electricity through the adhesive layer.
In some examples, the electrically-conductive elements in the adhesive layer may be in direct contact with both the first scarfed surface and the second scarfed surface. Such a configuration may simplify on-site assembly of the modular wind turbine blade, and may
DK 2022 00712 A1 provide an advantageously short, i.e. direct, electrical connection between the scarfed surfaces.
In some other examples, the scarf joint may further comprise electrically-conductive fibrous 5 material between the first and second scarfed surfaces. In such an example, the adhesive layer is preferably between the first scarfed surface and the electrically-conductive fibrous material, and the electrically-conductive elements in the adhesive layer are preferably in electrical contact with the first scarfed surface and the electrically-conductive fibrous material. In such examples, the modular wind turbine blade may further comprise a second adhesive layer between the electrically-conductive fibrous material and the second scarfed surface. Additionally, the blade may also comprise electrically-conductive elements in the second adhesive layer in electrical contact with the electrically-conductive fibrous material and the second scarfed surface.
It will be appreciated that the electrically-conductive elements in such an example are in electrical contact with the first and second scarfed surfaces through a combination of direct electrical contact and indirect electrical contact. For example, the electrically-conductive elements in each adhesive layer may be in direct electrical contact with one of the scarfed surfaces, and in indirect electrical contact with the other scarfed surface via the electrically- conductive fibrous material and the electrically-conductive elements in the other adhesive layer. As such, the electrically-conductive elements provide an electrically-conductive bridge through each adhesive layer, and the electrically-conductive fibrous material provides electrical conductivity between the electrically-conductive elements in the first and second adhesive layers.
The fibrous material between the first and second scarfed surfaces may be fixed in a cured resin matrix. For example, the fibrous material may be comprised in pre-preg fibrous material arranged between the first and second scarfed surfaces when assembling the modular wind turbine blade. Pre-preg fibrous material is fibrous material that is pre- impregnated with resin prior to arrangement between the first and second scarfed surfaces. The electrically-conductive fibrous material preferably comprises carbon fibres.
The inclusion of electrically-conductive fibrous material between the first and second scarfed surfaces may be advantageous for forming a strong joint between the scarfed surfaces. For example, manufacturing and assembly tolerances may result in small misalignments between the first and second scarfed surfaces when these are arranged to
DK 2022 00712 A1 6 form the scarf joint. As such, a bond gap defined between the first and second scarfed surfaces may vary in thickness. The arrangement of fibrous material, such as pre-preg fibrous material, in the scarf joint may help to alleviate potential risks related to a varying bond gap thickness. For example, the fibrous material may provide a cushioning effect when forming the scarf joint because the fibrous material may be configured to conform to the contours of the first and second scarfed surfaces. As such, the fibrous material may cushion variations in the first and second scarfed surfaces, i.e. smoothing out misalignments and minor surface defects.
In some examples, the modular wind turbine blade may comprise a plurality of layers of fibrous material in the scarf joint between the first and second scarfed surfaces. For example, each layer of fibrous material may comprise a layer of woven fibres, a layer of unidirectional fibres, a layer of biaxial fibres, a layer of multiaxial fibres, or a layer of fibres in the form of a chopped strand mat. A plurality of layers of fibrous material may conform — more closely to the contours of the scarfed surfaces. Further, arranging a plurality of layers of fibrous material between the first and second scarfed surfaces may increase the amount of fibrous material in the scarf joint, thereby increasing the strength of the joint.
As noted above, in preferred examples, the fibrous material provided between the first and second scarfed surfaces is pre-preg fibrous material. Using pre-preg fibrous material ensures that resin is provided throughout the bond gap such that there are no dry spots or voids in the scarf joint. The thorough provision of resin in the scarf joint ensures that stress concentrations between the spar cap and connecting element are minimised, and that a continuous load path is provided to transfer loads between the spar cap and connecting elementin use.
In some examples the elongate connecting element may be a separate spar component connected to the second spar cap. In such examples, the second spar cap preferably has a tapered end portion defining a third scarfed surface. The elongate connecting element preferably has a second tapered end portion defining a fourth scarfed surface configured for connection to the third scarfed surface of the second spar cap. Accordingly the elongate connecting element may be connected to the second spar cap via a second scarf joint comprising an adhesive layer between the third scarfed surface and the fourth scarfed surface. The second scarf joint may further comprise electrically-conductive elements in the adhesive layer and in electrical contact with both the third scarfed surface and the
DK 2022 00712 A1 7 fourth scarfed surface such that the electrically-conductive elements form an electrically- conductive bridge through the adhesive layer.
It will be appreciated that all features previously described with reference to the scarf joint between the first and second scarfed surfaces are equally applicable to the second scarf joint between the third and fourth scarfed surfaces and are not repeated here for conciseness.
In some examples, the spar caps and/or the connecting element may comprise a stack of pultrusions. The pultrusions may comprise electrically-conductive material, such as carbon fibre. Accordingly, the pultrusions may be carbon fibre reinforced polymer pultrusions. The use of pultrusions is advantageous because a pultrusion process enables close control of fibre orientation in the spar caps and connecting element. Pultrusions may therefore comprise longitudinally-extending reinforcing fibres in a highly uniform arrangement, which improves the strength of the spar caps and connecting element.
According to the present invention there is provided a method of assembling a modular wind turbine blade. The method comprises providing a first blade module and a second blade module, the first blade module comprising a first spar cap and the second blade module comprising a second spar cap. The first and second spar caps comprise an electrically-conductive material and the first spar cap has tapered end portion defining a first scarfed surface. The method further comprises providing an elongate connecting element for connecting the first and second blade modules. The elongate connecting element is either a) an end portion of the second spar cap, or b) separate from the first and second spar caps. The connecting element comprises an electrically-conductive material and has a tapered end portion defining a second scarfed surface configured for connection to the first scarfed surface of the first spar cap. The method further comprises arranging the first and second blade modules end to end, and connecting the first and second spar caps via a scarf joint formed between the first and second scarfed surfaces.
Connecting the first and second spar caps comprises providing adhesive between the first and second scarfed surfaces. Connecting the first and second spar caps further comprises providing electrically-conductive elements in the adhesive and in electrical contact with both the first scarfed surface and the second scarfed surface such that the electrically- conductive elements form an electrically-conductive bridge through the adhesive.
DK 2022 00712 A1 8
In some examples, the method of assembling the modular wind turbine blade may comprise arranging the electrically conductive elements in the adhesive and subsequently arranging the first and second scarfed surfaces together to form the scarf joint. in such an example the method may comprise curing the adhesive to bond the first scarfed surface to the second scarfed surface.
In some examples, the electrically-conductive elements may be elastically compressible.
In such an example, the method may further comprise compressing the electrically- conductive elements between the first and second scarfed surfaces, before the adhesive is cured. Elastically-compressible electrically-conductive elements preferably have a relaxed, i.e. uncompressed, thickness that is greater than the intended final thickness of the adhesive layer. As such, when compressed between the first and second scarfed surfaces, the electrically-conductive elements may exhibit a biasing force. In preferred examples the biasing force serves to press at least a portion of each electrically-conductive element towards each of the scarfed surfaces.
In some examples, the elastically-compressible electrically-conductive elements may comprise one or more helical springs. The helical springs may be compressed along their longitudinal axes between the first and second scarfed surfaces. Alternatively the electrically-conductive elements may comprise a helical spring arranged with its longitudinal axis substantially parallel to a scarfed surface. In other examples, the elastically-compressible electrically-conductive elements may comprise an undulating profile as previously described. Compressing an undulating electrically-conductive element between the first and second scarfed surfaces preferably results in a biasing force that serves to press a plurality of sections of the electrically-conductive element towards each scarfed surface. This helps to ensure than a plurality of electrically-conductive bridges are formed through the adhesive layer. Compressing the electrically-conductive elements between the first and second scarfed surfaces may flatten the undulating profile of the electrically-conductive elements.
In some examples, providing adhesive between the first and second scarfed surfaces comprises applying excess adhesive such that compressing the electrically-conductive elements between the first and second scarfed surfaces when forming the scarf joint causes the excess adhesive to be squeezed out of the scarf joint, thereby ensuring that the scarfed surfaces are thoroughly bonded together.
DK 2022 00712 A1 9
In some examples, the method may additionally comprise arranging electrically-conductive pre-preg fibrous material between the first and second scarfed surfaces. Pre-preg fibrous material comprises fibrous material that is pre-impregnated with uncured resin. Connecting the first and second spar caps may further comprise curing the resin in the pre-preg fibrous material to thereby connect the tapered end portion of the first spar cap to the tapered end portion of the connecting element.
In such examples, the adhesive is preferably provided between the first scarfed surface and the electrically-conductive fibrous material, and the electrically-conductive elements provided in the adhesive are preferably in electrical contact with the first scarfed surface and the electrically-conductive fibrous material. The method preferably further comprises providing adhesive between the electrically-conductive fibrous material and the second scarfed surface, and electrically-conductive elements are preferably provided in said adhesive in electrical contact with the electrically-conductive fibrous material and the — second scarfed surface.
In some examples in which pre-preg fibrous material is arranged between the scarfed surfaces, the adhesive provided between the first and second scarfed surfaces may be used to prime one or more of the scarfed surfaces. For example, the adhesive provided between the first scarfed surface and the electrically-conductive fibrous material may be applied to the first scarfed surface and cured prior to arrangement with the second scarfed surface to form the scarf joint. The electrically-conductive elements are preferably arranged in the adhesive applied to the first scarfed surface before the adhesive is cured.
Further, adhesive may be applied to the second scarfed surface and cured prior to arrangement with the first scarfed surface. Electrically-conductive elements are preferably arranged in the adhesive applied to the second scarfed surface before the adhesive is cured.
Priming the first and/or second scarfed surface with adhesive may improve the adhesion of the electrically-conductive pre-preg fibrous material to the first and/or second scarfed surface. For example, the adhesive may have a higher surface energy than the first and second scarfed surfaces and may therefore provide a more wettable surface for the resin in the pre-preg fibrous material to bond to. Further, the adhesive applied to the first and/or second scarfed surfaces may additionally aid in reducing variations in the bond gap thickness. For example, the adhesive may fill recesses or other surface roughness on the first and/or second scarfed surface, thereby further improving the strength of the scarf joint.
DK 2022 00712 A1 10
In some examples, the elongate connecting element may be separate from the first and second spar caps. The second spar cap may have a tapered end portion defining a third scarfed surface, and the connecting element may have a second tapered end portion defining a fourth scarfed surface. In such examples, the method may further comprise connecting the first and second spar caps via a second scarf joint formed between the third and fourth scarfed surfaces. Connecting the first and second spar caps may further comprise providing adhesive between the third and fourth scarfed surfaces. Connecting the first and second spar caps may further comprise providing electrically-conductive elements in the adhesive and in electrical contact with both the third scarfed surface and the fourth scarfed surface such that the electrically-conductive elements form an electrically-conductive bridge through the adhesive.
The method may further comprise curing the adhesive to bond the third scarfed surface to — the first scarfed surface. Alternatively, the method may comprise arranging electrically- conductive pre-preg fibrous material between the first and second scarfed surfaces. In such examples, the adhesive is preferably provided between the third scarfed surface and the electrically-conductive fibrous material, and the electrically-conductive elements provided in the adhesive are preferably in electrical contact with the third scarfed surface and the electrically-conductive fibrous material. The method preferably further comprises providing adhesive between the electrically-conductive fibrous material and the fourth scarfed surface, and electrically-conductive elements are preferably provided in said adhesive in electrical contact with the electrically-conductive fibrous material and the fourth scarfed surface. In such an example, connecting the first and second spar caps may further comprise curing the resin in the pre-preg fibrous material to thereby connect the tapered end portion of the second spar cap to the second tapered end portion of the connecting element.
The adhesive described above may be an epoxy adhesive.
It will be appreciated that all features previously described with reference to forming the scarf joint between the first and second scarfed surfaces are equally applicable to forming the scarf joint between the third and fourth scarfed surfaces and are not repeated here for conciseness.
DK 2022 00712 A1 11
Examples of the present invention will now be described by way of non-limiting example only, with reference to the accompanying figures, in which:
Figure 1 is a schematic exploded view of a modular wind turbine blade comprising first and second blade modules that are connected via a connecting element that is an end portion of a spar cap of the second blade module;
Figure 2 is a schematic exploded view of a modular wind turbine blade comprising a connecting element that is separate from the spar caps of the first and second blade modules;
Figure 3 is a schematic cross-sectional view of a scarf joint between a spar cap and the connecting element, the scarf joint comprising an adhesive layer and a plurality of electrically-conductive elements in the adhesive layer;
Figure 4 is a schematic cross-sectional view of a scarf joint wherein the electrically- conductive elements comprise a plurality of layers of unidirectional fibre tows;
Figure 5 is a schematic cross-sectional view of a scarf joint wherein the electrically- conductive elements comprise a layer of woven electrically-conductive fibres;
Figure 6a is a schematic cross-sectional view of a scarf joint comprising an electrically- conductive element having an undulating profile;
Figures 6b, 6c, 6d and 6e show further examples of electrically-conductive elements that have an undulating profile;
Figure 7 is a schematic cross-sectional view of a scarf joint that additionally comprises fibrous material arranged between scarfed surfaces that are primed with an adhesive layer; and
Figure 8 is a schematic cross-sectional view of an example wherein the connecting element is a separate spar component connected to spar caps of each blade module via scarf joints comprising adhesive layers and electrically-conductive elements in the adhesive layers.
As described above by way of background, assembling a wind turbine blade from a plurality of blade modules may facilitate the provision of larger wind turbine blades whilst
DK 2022 00712 A1 12 still enabling transport of large blade parts to the wind turbine site. The schematic exploded views of Figures 1 and 2 show examples of a modular wind turbine blade 10 comprising a first blade module 12a and a second blade module 12b that are connectable together to form at least part of the blade 10. Unless otherwise stated, the following description applies equally to the blade 10 shown in Figure 1 and to the blade 10 shown in Figure 2.
With reference to Figures 1 and 2, the first blade module 12a comprises a first spar cap 14a which may be part of a spar structure that provides structural support to an outer shell 16a of the first blade module 12a. Similarly, the second blade module 12b comprises a second spar cap 14b which may be part of a spar structure that provides structural support to an outer shell 16b of the second blade module 12b.
As will be described later in more detail, the first and second spar caps 14a, 14b are configured to be connected together via a scarf joint. As such, the first spar cap 14a has a tapered end portion 18a defining a first scarfed surface 20a. The modular wind turbine blade 10 further comprises an elongate connecting element 22 for connecting the first and second blade modules 12a, 12b. With reference initially to Figure 1, the connecting element 22 may be defined by an end portion 18b of the second spar cap 14b. For example, the connecting element 22 may be defined by a portion of the second spar cap 14b that extends beyond the outer shell 16b of the second blade module 12b. Referring to
Figure 2, in other examples the connecting element 22 may be a spar component that is separate from, and connectable to, the first and second spar caps 14a, 14b. In both examples, the connecting element 22 has a tapered end portion 24a defining a second scarfed surface 20b. The second scarfed surface 20b is configured for connection to the first scarfed surface 20a, i.e. to the first spar cap 14a.
With reference still to Figures 1 and 2, to assemble the modular wind turbine blade 10 the first and second blade modules 12a, 12b are arranged end-to-end. For example, the first and second blade modules 12a, 12b are preferably arranged such that longitudinal axes of the first and second spar caps 14a, 14b are substantially co-axial. The first and second spar caps 14a, 14b are connected via a scarf joint formed between the first and second scarfed surfaces 20a, 20b, as shown in Figure 3.
Figure 3 shows a schematic cross-sectional view of a scarf joint 26. The scarf joint 26 helps to transfer loads safely and effectively between the first and second spar caps 14a, 14b. The scarf joint 26 may be a scarf joint formed between the first spar cap 14a and the connecting element 22 defined by the end portion 18b of the second spar cap 14b, as
DK 2022 00712 A1 13 shown in Figure 1. Alternatively, the scarf joint 26 may be a scarf joint formed between the first spar cap 14a and the separate connecting element 22 as shown in Figure 2.
The scarf joint 26 comprises an adhesive layer 28 between the first scarfed surface 20a and the second scarfed surface 20b. In some examples, as shown in Figure 3, the first and second scarfed surfaces 20a, 20b may be bonded together by the adhesive layer 28.
In other examples, as shown in Figure 7 and described later in more detail, the scarf joint 26 may comprise one or more layers of fibrous material between the first and second scarfed surfaces 20a, 20b. Whilst the scarf joint 26 in such examples also comprises an adhesive layer 28, the first and second scarfed surfaces 20a, 20b may be connected — together via the fibrous material, which may be fixed in a cured resin matrix.
With reference still to Figure 3, in each of the examples described herein the first and second spar caps 14a, 14b each comprise an electrically-conductive material. For example, the spar caps 14a, 14b may comprise pultrusions formed of carbon fibre reinforced polymer. In examples comprising a separate connecting element 22, such a connecting element also comprises an electrically-conductive material, such as carbon fibre. For example, the separate connecting element 22 may comprise a stack of pultrusions, such as carbon fibre reinforced polymer pultrusions.
Adhesive is typically electrically-insulating, and providing an electrically-insulating barrier between the first and second scarfed surfaces 20a, 20b may introduce a risk of flashovers, — or electrical arcs, between the spar cap 14a and connecting element 22 in the event of a lightning strike, as described by way of background. However, in each of the examples described herein, the scarf joint 26 comprises electrically-conductive elements 30 in the adhesive layer 28 to form an electrically-conductive bridge through the adhesive layer 28.
Referring still to Figure 3, the electrically-conductive elements 30 in the adhesive layer 28 are in electrical contact with both the first scarfed surface 20a and the second scarfed surface 20b. As shown in Figure 3, in some examples the electrically-conductive elements in the adhesive layer 28 may be in direct contact with both the first scarfed surface 20a and the second scarfed surface 20b. In other words, the electrically conductive elements 30 may be in direct electrical contact with both the first and second scarfed surfaces 20a, 30 — 20b.
In some examples, the electrically-conductive elements 30 may comprise electrically- conductive fibres. In the example shown in Figure 3, the electrically-conductive elements 30 comprise a plurality of electrically-conductive fibre tows 32. The tows 32 comprise a
DK 2022 00712 A1 14 plurality of conductive fibres, such as carbon fibres for example. As shown in Figure 3, in some examples the electrically-conductive elements 30 comprise a layer of unidirectional fibre tows 32 which extend longitudinally in a substantially chordwise direction C, i.e. into the page in Figure 3.
As shown in Figure 4, in some examples the electrically-conductive elements 30 may comprise a plurality of layers of unidirectional electrically-conductive fibre tows 32. For example, the conductive elements 30 may comprise a first layer of fibre tows 32a and a second layer of fibre tows 32b oriented transverse to the first layer. The first and second layers of electrically conductive fibre tows 32a, 32b are preferably in electrical contact with one another as shown in Figure 4. In preferred examples, the combined thickness of the transversely-arranged layers of fibre tows 32a, 32b is substantially the same as the thickness of the adhesive layer 28 such that the fibre tows 32 form an electrically- conductive bridge through the adhesive layer 28.
Figure 5 shows an example of a scarf joint 26 wherein the electrically-conductive elements 30in the adhesive layer 28 comprise a layer of woven electrically-conductive fibres 34. In some examples the layer of woven fibres 34 may comprise woven fibre tows. The layer of woven fibres 34, or woven fibre tows, preferably has a thickness that is substantially equal to the thickness of the adhesive layer 28 in locations where the fibres or fibre tows overlap.
Whilst not shown in the accompanying figures, in some examples the electrically conductive elements 30 may comprise short chopped fibres in the adhesive layer 28 to form an electrically-conductive bridge. In some examples, the electrically-conductive elements 30 may comprise short chopped fibres in combination with the fibre tows 32 and/or woven fibres 34 described previously. In such examples, the fibre tows 32 and/or woven fibres 34 advantageously help to retain the short chopped fibres in the adhesive layer 28 during assembly of the modular wind turbine blade 10.
Figure 6a shows an example of a scarf joint 26 comprising an electrically-conductive element 30 that has an undulating profile. As shown in Figure 6a, an electrically-conductive element 30 with an undulating profile preferably comprises a plurality of sections 36a in proximity to the first scarfed surface 20a, and a plurality of sections 36b in proximity to the second scarfed surface 20b. As such, in some examples an electrically-conductive element 30 may alternate between proximity to the first scarfed surface 20a and proximity to the second scarfed surface 20b, extending repeatedly between sides of the adhesive
DK 2022 00712 A1 15 layer 28. Such a configuration may help to ensure that a plurality of electrically conductive bridges are formed through the adhesive layer 28.
In preferred examples, the electrically conductive elements 30 may be elastically compressible. Elastically-compressible electrically-conductive elements 30 may be particularly advantageous in examples where the electrically-conductive elements 30 have an undulating profile. For example, the electrically-conductive elements 30 may be arranged in a wet, uncured adhesive layer 28 when assembling the modular wind turbine blade 10. Arranging the first and second scarfed surfaces 20a, 20b together to form the scarf joint 26 may involve compressing the electrically-conductive elements 30 in the adhesive layer 28 between the scarfed surfaces 20a, 20b. As such, the electrically- conductive elements 30 may exhibit a biasing force pushing sections 36a, 36b of the electrically-conductive element 30 towards each of the scarfed surfaces 20a, 20b. This may help to ensure that a plurality of sections 36a, 36b of an undulating electrically- conductive element 30 are brought into electrical contact with the first and second scarfed surfaces 20a, 20b.
Whilst Figure 6a shows an example of an undulating electrically-conductive element 30 that has an abruptly undulating profile, i.e. a zig-zag profile, Figures 6b and 6d each show other examples of undulating electrically-conductive elements 30. With brief reference to
Figure 6b, an undulating electrically-conductive element 30 may have a rounded undulating profile, such as a sinusoidal profile for example. Figure 6d shows an electrically- conductive element 30 having a more abruptly undulating profile, such as a stepped profile for example.
Figures 6¢ and 6d show examples of the electrically-conductive elements 30 of Figures 6b and 6d respectively, following compression between the first and second scarfed surfaces 20a, 20b. As shown in Figures 6c and 6d, compressing the electrically-conductive elements 30 between the first and second scarfed surfaces 20a, 20b may result in the undulating profiles being flattened. However, with reference also to Figure 6a, the electrically-conductive elements 30 preferably still comprise sections 36a proximal to the first scarfed surface 20a and sections 36b proximal to the second scarfed surface 20b to form an electrically conductive bridge, when compressed in the adhesive layer 28.
Referring now to Figure 7, in some examples the scarf joint 26 may additionally include electrically-conductive fibrous material 38 between the first and second scarfed surfaces 20a, 20b. The electrically-conductive fibrous material 38 may be comprised in pre-preg
DK 2022 00712 A1 16 material that is arranged between the scarfed surfaces 20a, 20b when assembling the modular wind turbine blade 10. Pre-preg fibrous material 38 is fibrous material that is pre- impregnated with uncured resin prior to arrangement between the scarfed surfaces 20a, 20b. Arranging electrically-conductive pre-preg fibrous material 38 between the scarfed surfaces 20a, 20b may provide an advantageous cushioning effect between the scarfed surfaces 20a, 20b. For example, the pre-preg fibrous material 38 may conform to the contours of the first and second scarfed surfaces 20a, 20b to alleviate misalignments, surface features or other inaccuracies that could result in a variable bond-gap thickness between the first and second scarfed surfaces 20a, 20b.
As shown in Figure 7, in examples where electrically-conductive fibrous material 38 is arranged between the first and second scarfed surfaces 20a, 20b, the modular blade 10 preferably comprises an adhesive layer 28 between the fibrous material 38 and each of the scarfed surfaces 20a, 20b. The adhesive layers 28 help to prime the scarfed surfaces 20a, 20b to provide a suitable surface for the resin in the pre-preg fibrous material 38 to adhere to. For example, the adhesive layers 28 may have a higher surface energy than the spar caps 14a, 14b and/or connecting element 22. Providing adhesive 28 between the fibrous material 38 and each of the scarfed surfaces 20a, 20b may therefore provide an advantageously strong scarf joint 26.
The description provided previously in relation to examples of electrically-conductive elements 30 that provide an electrically conductive bridge through an adhesive layer 28 is equally applicable to examples wherein the scarf joint 26 additionally comprises fibrous material 38, as shown in Figure 7. In such examples, the electrically-conductive elements 30 similarly provide an electrically-conductive bridge through each adhesive layer 28.
Further description of the electrically-conductive elements 30 and their function will not be repeated here for conciseness.
In examples comprising fibrous material 38 in the scarf joint 26, the electrically-conductive elements 30 in a first adhesive layer 28 preferably provide an electrically-conductive bridge between the first scarfed surface 20a and the fibrous material 38. Further, the electrically- conductive elements 30 in a second adhesive layer 28 preferably provide an electrically- conductive bridge between the fibrous material 38 and the second scarfed surface 20b.
Continuous electrical conductivity is therefore facilitated between the spar cap 14a and the connecting element 22 via the electrically-conductive fibrous material 38 and the electrically-conductive elements 30 in each of the adhesive layers 28.
DK 2022 00712 A1 17
Figure 8 shows a cross-sectional view of a connecting element 22 that is a separate spar component connected between the first and second spar caps 14a, 14b, such as the connecting element 22 shown in the example of Figure 2. With reference additionally to
Figure 2, the second spar cap 14b in such an example may have a tapered end portion 18b that defines a third scarfed surface 20c. Further, the connecting element 22 may have a second tapered end portion 24b that defines a fourth scarfed surface 20d. It follows that the elongate connecting element 22 may be connected to the second spar cap 14b via a second scarf joint 26 comprising an adhesive layer 28 between the third scarfed surface 20c and the fourth scarfed surface 20d.
As previously described with reference to the first scarf joint 26 formed between the first and second scarfed surfaces 20a, 20b, the second scarf joint 26 preferably comprises electrically-conductive elements 30 in the adhesive layer 28. The electrically-conductive elements 30 are preferably in electrical contact with both the third and fourth scarfed surfaces 20c, 20d, to provide an electrically-conductive bridge through the adhesive layer 28.
In some examples, as shown in Figure 8, the electrically-conductive elements 30 may be in direct contact with the third and fourth scarfed surfaces 20c, 20d. In other examples, the second scarf joint 26 may comprise electrically conductive fibrous material 38 arranged between the third and fourth scarfed surfaces 20c, 20d, and the second scarf joint 26 may comprise adhesive layers 28 and electrically conductive elements 30 arranged in the adhesive layers 28 in the same way as previously described with reference to the first scarf joint 26 in Figure 7. In each of these examples, the electrically-conductive elements 30 in each adhesive layer 28 provide an electrically-conductive bridge through the respective adhesive layer 28.
It will be appreciated that the description provided above serves to demonstrate a plurality of possible examples of the present invention. Features described in relation to any of the examples above may be readily combined with any other features described with reference to different examples without departing from the scope of the invention as defined in the appended claims.
Claims (12)
1. A modular wind turbine blade comprising: a first blade module and a second blade module connectable together to form at least part of the modular wind turbine blade, the first blade module comprising a first spar cap and the second blade module comprising a second spar cap, the first and second spar caps comprising an electrically-conductive material, and the first spar cap having a tapered end portion defining a first scarfed surface; an elongate connecting element for connecting the first and second blade modules, the elongate connecting element being either a) an end portion of the second spar cap, or b) a separate spar component connected to the second spar cap, the connecting element comprising an electrically-conductive material and having a tapered end portion defining a second scarfed surface configured for connection to the first scarfed surface of the first spar cap; the first and second spar caps being connected via a scarf joint comprising an adhesive layer between the first scarfed surface and the second scarfed surface, the scarf joint further comprising electrically-conductive elements in the adhesive layer and in electrical contact with both the first scarfed surface and the second scarfed surface such that the electrically-conductive elements form an electrically-conductive bridge through the adhesive layer.
2. The modular wind turbine blade of Claim 1, wherein the electrically-conductive elements comprise electrically-conductive fibres.
3. The modular wind turbine blade of Claim 1 or Claim 2, wherein the electrically- conductive elements comprise electrically-conductive fibres.
4. The modular wind turbine blade of Claim 3, wherein the electrically-conductive elements comprise a first layer of unidirectional electrically-conductive fibres and a second layer of unidirectional electrically-conductive fibres in electrical contact with the first layer of fibres and oriented transverse to the first layer.
5. The modular wind turbine blade of Claim 1 or Claim 2, wherein the electrically- conductive elements comprise a layer of woven electrically-conductive fibres.
DK 2022 00712 A1 19
6. The modular wind turbine blade of Claim 1 or Claim 2, wherein the electrically- conductive elements have an undulating profile.
7. The modular wind turbine blade of any preceding claim, wherein the electrically- conductive elements in the adhesive layer are in direct contact with both the first scarfed surface and the second scarfed surface.
8. The modular wind turbine blade of any of Claims 1 to 6, wherein the scarf joint further comprises electrically-conductive fibrous material between the first and second — scarfed surfaces; wherein the adhesive layer is between the first scarfed surface and the electrically- conductive fibrous material, and wherein the electrically-conductive elements in the adhesive layer are in electrical contact with the first scarfed surface and the electrically- conductive fibrous material; the modular wind turbine blade further comprising: a second adhesive layer between the electrically-conductive fibrous material and the second scarfed surface; and electrically-conductive elements in the second adhesive layer in electrical contact with the electrically-conductive fibrous material and the second scarfed surface.
9. The modular wind turbine blade of any preceding claim, wherein the elongate connecting element is a separate spar component connected to the second spar cap, the second spar cap having a tapered end portion defining a third scarfed surface, and the elongate connecting element having a second tapered end portion defining a fourth scarfed surface configured for connection to the third scarfed surface of the second spar cap, the elongate connecting element being connected to the second spar cap via a second scarf joint comprising an adhesive layer between the third scarfed surface and the fourth scarfed surface, the second scarf joint further comprising electrically- conductive elements in the adhesive layer and in electrical contact with both the third scarfed surface and the fourth scarfed surface such that the electrically-conductive elements form an electrically-conductive bridge through the adhesive layer.
10. A method of assembling a modular wind turbine blade comprising: providing a first blade module and a second blade module, the first blade module comprising a first spar cap and the second blade module comprising a second spar cap,
DK 2022 00712 A1 20 the first and second spar caps comprising an electrically-conductive material, and the first spar cap having a tapered end portion defining a first scarfed surface; providing an elongate connecting element for connecting the first and second blade modules, the elongate connecting element being either a) an end portion of the second spar cap, or b) separate from the first and second spar caps, the connecting element comprising an electrically-conductive material and having a tapered end portion defining a second scarfed surface configured for connection to the first scarfed surface of the first spar cap; arranging the first and second blade modules end to end; connecting the first and second spar caps via a scarf joint formed between the first and second scarfed surfaces; wherein connecting the first and second spar caps comprises: providing adhesive between the first and second scarfed surfaces; and providing electrically-conductive elements in the adhesive and in electrical contact — with both the first scarfed surface and the second scarfed surface such that the electrically- conductive elements form an electrically-conductive bridge through the adhesive.
11. The method of Claim 10, wherein the electrically-conductive elements are elastically compressible, and wherein the method further comprises compressing the — electrically-conductive elements between the first and second scarfed surfaces.
12. The method of Claim 10 or Claim 11, wherein the elongate connecting element is separate from the first and second spar caps, wherein the second spar cap has a tapered end portion defining a third scarfed surface, and wherein the connecting element has a second tapered end portion defining a fourth scarfed surface, the method further comprising: connecting the first and second spar caps via a second scarf joint formed between the third and fourth scarfed surfaces; wherein connecting the first and second spar caps further comprises: providing adhesive between the third and fourth scarfed surfaces; and providing electrically-conductive elements in the adhesive and in electrical contact with both the third scarfed surface and the fourth scarfed surface such that the electrically- conductive elements form an electrically-conductive bridge through the adhesive.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA202200712A DK202200712A1 (en) | 2022-07-22 | 2022-07-22 | Modular wind turbine blade |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DKPA202200712A DK202200712A1 (en) | 2022-07-22 | 2022-07-22 | Modular wind turbine blade |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DK202200712A1 true DK202200712A1 (en) | 2023-07-11 |
Family
ID=87103651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DKPA202200712A DK202200712A1 (en) | 2022-07-22 | 2022-07-22 | Modular wind turbine blade |
Country Status (1)
| Country | Link |
|---|---|
| DK (1) | DK202200712A1 (en) |
-
2022
- 2022-07-22 DK DKPA202200712A patent/DK202200712A1/en not_active Application Discontinuation
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9816482B2 (en) | Spar cap for a wind turbine rotor blade | |
| CN109098929B (en) | Wind turbine blade with hybrid spar cap and associated method of manufacture | |
| CN113316683B (en) | Equipotential bonding of wind turbine rotor blades | |
| EP3418556B1 (en) | A wind turbine blade with hybrid spar cap and associated method for making | |
| CN113316684B (en) | Equipotential bonding of wind turbine rotor blades | |
| EP1746284B2 (en) | Wind turbine blade | |
| US20180156202A1 (en) | Spar cap assembly for a wind turbine rotor blade | |
| CA2913600C (en) | Conductor joint and conductor joint component | |
| EP3569394A1 (en) | Method of manufacturing a spar cap | |
| EP2971756B1 (en) | Wind turbine blades with layered, multi-component spars, and associated systems | |
| EP3726049B1 (en) | Rotor blade and method for manufacturing a rotor blade | |
| CN114630957A (en) | Wind turbine blade | |
| DK202200712A1 (en) | Modular wind turbine blade | |
| CN114450147B (en) | Method of manufacturing a structural element of a wind turbine blade, method of manufacturing a wind turbine blade, structural element of a wind turbine blade and wind turbine blade | |
| WO2023227420A1 (en) | A wind turbine blade with an improved lightning protecting system | |
| CN113167219A (en) | Spar structure with integrated lower conductor element for lightning protection system | |
| WO2024017450A1 (en) | Improvements relating to modular wind turbine blades | |
| WO2022106351A1 (en) | A spar cap assembly for a wind turbine blade with a lightning protection system | |
| WO2024017449A1 (en) | Improvements relating to modular wind turbine blades | |
| RU2743770C1 (en) | Composite longeron | |
| EP4133178B1 (en) | A wind turbine blade, a wind turbine and a method for manufacturing a wind turbine blade | |
| CN116412060B (en) | Web of blade and blade | |
| CN117795190A (en) | Winged spar cap configuration for a spliced wind turbine blade | |
| WO2022188934A1 (en) | Wind turbine rotor blade spar cap with equipotential bonding |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PAB | Application published on request |
Effective date: 20230710 |
|
| PHB | Application deemed withdrawn due to non-payment or other reasons |
Effective date: 20230714 |