Patent Application
20090146433
This invention relates generally to rotary machines and more particularly, to methods and apparatus for fabricating wind turbine blades.
Generally, a wind turbine generator includes a rotor having multiple blades. The rotor is sometimes mounted within a housing, or nacelle, that is positioned on top of a base, for example a truss or tubular tower. At least some known utility grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) can have rotor blades of 30 meters (m) (100 feet (ft)) or more in length.
Many known wind turbine blades are generally difficult and time consuming to assemble. Some known methods of fabricating wind turbine blades include forming a plurality of members using resin transfer molding techniques. Such techniques typically include placing a preshaped fiber reinforcement preform into a closed molding of a similar shape, transferring a resin into the mold such that the resin impregnates the reinforcing fibers, and allowing the resin to cure to form a fiberglass-reinforced wind turbine blade member. A variety of members are formed in this manner and are assembled together to fabricate wind turbine blades.
At least one method of assembling wind turbine blades includes using adhesives applied to some of the bonding surfaces, for example, adhesively bonding two members together to define a blade cross section having a leading edge and a trailing edge. This method uses a large amount of adhesives that increases assembly costs due to extensive material usage as well as the labor usage to apply the adhesive. Moreover, as the associated members are placed in contact with each other, adhesive material is squeezed out of the associated joints and the wastage is disposed of. Also, manually applying the adhesive facilitates uneven adhesive thicknesses across the length of the blade (which facilitates squeezed wastage as described above), and void formation. Furthermore, joining the fiberglass members is typically performed at a blade chord line, wherein member alignment is made more difficult and erosion resistance and aerodynamic integrity may be deleteriously affected.
In one aspect, a method of assembling a wind turbine blade is provided. The method includes forming a preform pressure surface member and a preform suction surface member. The method also includes forming at least one of a leading edge and a trailing edge. One method of forming the leading edge or the trailing edge includes coupling a preform cap member to one of a portion of the preform pressure surface member and a portion of the preform suction surface member. At least a portion of one of the preform pressure surface member and the preform suction surface member overlap at least a portion of the preform bond cap member. Another method of forming the leading edge or the trailing edge includes coupling the preform pressure surface member to the preform suction surface member wherein at least a portion of the preform pressure surface member overlaps at least a portion of the preform suction surface member.
In another aspect, a wind turbine blade is provided. The wind turbine blade includes a pressure surface member, a suction surface member and at least one of a leading edge and a trailing edge. Either the leading and trailing edge is formed with one of a cap member overlapping a portion of the pressure surface member and a portion of the suction surface member, or formed with an overlapping region that is formed with at least a portion of the pressure surface member overlapping at least a portion of the suction surface member.
In a further aspect, a wind turbine generator is provided. The wind turbine generator includes an electric generator rotatingly coupled to a hub and a wind turbine blade coupled to the hub. The wind turbine blade includes a pressure surface member, a suction surface member and at least one of a leading edge and a trailing edge. Either the leading and trailing edge is formed with one of a cap member overlapping a portion of the pressure surface member and a portion of the suction surface member, or formed with an overlapping region that is formed with at least a portion of the pressure surface member overlapping at least a portion of the suction surface member.
Unassembled portion 153 includes a preform pressure member, or lower shell preform member 161, and an adjoining bond cap preform member 188. Lower shell preform member 161 forms lower shell 120 (shown in
Apparatus 150 further includes a silicon rubber insert 174 that is inserted between flanges 156 and 160. Insert 174 is configured to mitigate resin flow out of apparatus 150 via flanges 156 and 160. In the exemplary embodiment, insert 174 has any dimensions that facilitate operation of apparatus 150 as described herein.
Apparatus 150 also includes a vacuum port 180 that penetrates flange 160. Apparatus 150 further includes at least one exemplary prefabricated clip 182. Clip 182 is configured to secure bond cap preform member 188 to bond cap support portion 154. Moreover, each of clips 182 is configured for a specific position (not shown) along a longitudinal length (not shown) of bond cap fixture 151. Furthermore, each clip 182 is configured to include an induced closing bias that facilitates a mild “pinching” action as described below as well as facilitating ease of removal. In the exemplary embodiment, clip 182 has any dimensions that facilitate operation of apparatus 150 as described herein.
Additional fiberglass layers 186 are positioned on top of foam 164 and fiberglass layers 162 within shell formation portion 158 and up to mold flange 160. In the exemplary embodiment, layers 186 are formed with biax. Alternatively, layers 186 are formed from materials that include, but are not limited to, triax. At least one bond cap preform member 188 is positioned on top of layers 186 and against bond cap support portion 154 such that at least a portion of each of members 188 and 161 are in direct contact with each other. Member 188 is configured to form bond cap 129 (shown in
Bond cap preform member 188 is secured to apparatus 150 along the longitudinal length (not shown) of bond cap fixture 151 via methods that include, but are not limited to, a plurality of clips 182, glass tape, clamping devices with padded jaws and spring-loaded clips (neither shown). In the exemplary embodiment, the clamps and spring-loaded clips are used within a 15 meter (m) (49.2 feet (ft)) longitudinally inboard-most portion (not shown) of bond cap fixture 151 and clips 182 are positioned at 0.5 m (19.7 in.) intervals along the longitudinal length of bond cap fixture 151. Alternatively, clips 182, tape, clamps and spring-loaded clips are positioned at any portion of fixture 151 at any intervals that facilitate operation of apparatus 150 as described herein. The induced “pinch” bias within clips 182 facilitates securing bond cap preform member 188 to fixture 151 and mold 152 with a predetermined alignment while mitigating deleterious distortion of member 188.
Also, alternatively, methods of securing bond cap preform member 188 to apparatus 150 include stitching at least a portion of bond cap preform member 188 to at least a portion of lower shell preform member 161 with a stitching material (not shown). Subsequently, the method includes securing at least a portion of the stitching material to one of lower mold 152 and bond cap fixture 151. A further alternative method of securing bond cap preform member 188 to apparatus 150 includes positioning at least one glass tie (not shown) over at least a portion of bond cap fixture 151 and bond cap preform member 188. Moreover, another alternative method of securing bond cap preform member 188 to apparatus 150 includes applying at least one bonding material (not shown) to at least a portion of bond cap fixture 151 and bond cap preform member 188.
Assembly apparatus 150 also includes at least a portion of an infusion apparatus, or vacuum bag 200. Bag 200 is positioned over substantially all of apparatus 150 and sealed. Subsequently, in the exemplary embodiment, air is withdrawn from inside apparatus 150 via vacuum port 180 and resin is introduced via ports (not shown) such that resin infusion of layers 186 and 162, foam 164, and bond cap preform member 188 is facilitated. In the exemplary embodiment, vacuum assisted resin transfer methods (VARTM), sometimes referred to as vacuum assisted resin injection (VARI) methods, are used. Alternatively, any resin transfer molding (RTM) methods that facilitate integrally bonding bond cap preform member 188 to lower shell preform member 161 as described herein are used. Upon completion of resin infusion, member 161 and member 188 are cured together to form an infused joint 201, thereby integrally bonding bond cap 129 to lower shell 120 (both shown in
In general, both HLU operations and prepreg material methods include use of at least one sealing member 189. Further, in general, HLU operations include applying a resin (not shown) to at least a portion of a non-resin-impregnated piece, or sheet, of fiberglass or cloth to form an at least partially-resin-impregnated sealing member 189. Moreover, in general, prepreg methods include using a sealing member 189 that, in this case, is a previously resin-impregnated piece, or sheet, of fiberglass or cloth. HLU operations and prepreg methods both include positioning at least a portion of resin-impregnated sealing member 189 such that it contacts at least a portion of lower shell 120 and at least a portion of bond cap 129 subsequent to curing of shell 120 and cap 129. Alternatively, sealing members 189 are positioned on at least a portion of each of lower shell preform member 161/lower shell 120 and an upper shell preform member 191/upper shell 122 either after partial curing or prior to any curing. Regardless, performing HLU operations and/or prepreg methods as described herein facilitates at least partially forming a HLU and/or pregreg joint 190. Also, alternatively, any method of bonding that includes, but is not limited to, HLU operations, prepreg methods, and RTM, in any portions of leading edge 128, that facilitates integrally bonding lower shell 120 to bond cap 129 as described herein are used.
Upper shell 122 is fabricated in a manner substantially similar to lower shell 120, with the exception that upper shell 122 is formed from upper shell preform member 191. Upper shell 122 is lowered onto bond cap 129 subsequent to resin infusion and curing of upper shell preform member 191 to form upper shell 122 using methods similar to that as described above. Therefore, bond cap 129 is configured to receive upper shell 122. Specifically, prior to resin infusion and curing, bond cap preform member 188 is formed as described above such that after curing and formation of bond cap 129, a bonded region, or joint 202, is at least partially formed between bond cap 129 and a portion of upper shell 122. Moreover, bonded joint 202 extends between a portion of bond cap 129 and a portion of lower shell 120, and may also extend between portions of lower shell 120 and upper shell 122.
Further, in the exemplary embodiment, prior to lowering upper shell 122 onto bond cap 129, an adhesive layer 204 is formed on a surface 206 of bond cap 129. Therefore, when upper shell 122 is lowered onto bond cap 129, adhesion of shell 122 to bond cap 129 is facilitated fully forms bonded joint 202. Bonded joint 202 has a thickness dimension 214. In the exemplary embodiment, dimension 214 is approximately 6 mm (0.236 in.). Alternatively, dimension 214 has any value that facilitates bonding bond cap 129 within blade 112 as described herein.
Alternatively, in lieu of forming adhesive layer 204, upper shell 122 is lowered into bond cap 129, thereby defining at least one void (not shown) in the vicinity of surface 206. Resin is injected into such voids to at least partially form bonded joint 202.
Additional methods of sealing bond cap 129 to shell 122 include, but are not limited to, HLU operations. In the exemplary embodiment, bonding upper shell 122 to lower shell 120 and integrated bond cap 129 defines a bond line 207 that is substantially coincident with chord line 144. Alternative embodiments are discussed further below. Once sealing operations are completed, bond cap 129, adhesive 204, HLU/prepreg joint 190, infusion joint 201, bonded joint 202, and portions of upper shell 122 and lower shell 120 cooperate to form leading edge 128.
An exemplary method of assembling wind turbine blade 112 includes forming a preform pressure surface member, or lower shell preform member 161, that subsequently forms lower shell assembly 120. The method also includes forming a preform suction surface, or upper shell preform member 191, that subsequently forms upper shell assembly 122. The method further includes forming at least one of leading edge 128 and trailing edge 130. One method of forming leading edge 128 and trailing edge 130 includes coupling preform cap member 188 to at least one of a portion of lower shell preform member 161 and a portion of upper shell preform member 191. A portion of at least one of lower shell preform member 161 and upper shell preform member 191 overlap at least a portion of preform bond cap member 188.
Using the above methods to form blade 112 facilitates reducing adhesive usage and wastage as well as overall blade 112 fabrication time and costs, including, substantially eliminating production floor use for prefabrication of bond cap 129 independent of the remainder of blade 112 components. Moreover, blade labor and material production costs that include, but are not limited to, bond cap prefabrication, adhesive application to bond cap 129 for bonding with lower shell 120, resin curing energy usage, miscellaneous consumable usage, bond cap molds, and adhesive wastage are reduced or eliminated. Furthermore, the overall quality of forming blade 112 is improved by facilitating a mitigation of void formation and component misalignment. Also, in the exemplary embodiment, an improvement of shear strength of the integral bond of approximately 150% over that associated with the adhesive alone is realized. Therefore, off-line blade repair costs are also reduced.
Therefore, in the alternative embodiment, shell 320 and 322 cooperate to form a shifted split line, or an alternative bond line 307 that is shifted, or separated by a distance 316 extending away from chord line 144 toward sidewall 324. Alternatively, blade 312 is configured to include alternative bond line 307 that is separated by distance 316 extending away from chord line 144 toward sidewall 326. In the exemplary embodiment, distance 316 is approximately 5.0 mm (0.2 in). Alternatively, distance 316 is any distance that facilitates operation of blade 312 as described herein.
Alternative blade 312 also includes an alternative bond cap 329, formed from an alternative bond cap preform member 388, that is substantially similar to bond cap 129 (shown in
Alternative blade 312 may include resin injected into joint 302 and may further include an alternative sealing member 389 that facilitates forming an alternative HLU and/or prepreg joint 390. Once sealing operations are completed, bond cap 329, adhesive 304, HLU/prepreg joint 390, infusion joint 301, bonded joint 302, and portions of upper shell 322 and lower shell 320 cooperate to form an alternative leading edge 328.
Moreover, in this alternative embodiment, overlapping portions 402 and 404 cooperate to form an overlapping region 400 that includes an alternative infusion joint 401. Also, in this alternative embodiment, overlapping portions 402 and 404 and infusion joint 401 cooperate to form a bond region 406. Specifically, bond region 406 is formed at the junction of sidewalls 424 and 426. Bond region 406 is further sealed with methods that include, but are not limited to, HLU operations, prepreg methods, and bonding with an adhesive. In some alternative embodiments, blade 412 further includes an alternative sealing member 489 that facilitates forming an alternative HLU/prepreg joint 490. Once sealing operations are completed, first and second overlapping portions 302 and 404, HLU/prepreg joint 490, infusion joint 401, and bond region 406 cooperate to form an alternative leading edge 428.
Further, in this alternative embodiment, bond region 406 is substantially coincident with chord line 144. Alternatively, overlapping regions 402 and 404 are fabricated such that bond region 406 extends beyond chord line 144 in either direction, that is toward either of sidewalls 424 and 426, with any distance that facilitates operation of alternative blade 412 as described herein.
An alternative method of assembling wind turbine blade 112, or more specifically, an alternative wind turbine blade 412, includes forming a preform pressure surface member, or lower shell preform member 461, that subsequently forms lower shell assembly 420. The method also includes forming a preform suction surface, or upper shell preform member 491, that subsequently forms upper shell assembly 422. The method further includes forming at least one of leading edge 428 and a trailing edge (not shown). One method of forming leading edge 428 and the trailing edge includes coupling preform pressure surface member 461 to preform suction surface member 491 wherein at least a portion of preform pressure surface member 461 overlaps at least a portion of preform suction surface member 491.
The methods and apparatus for fabricating a wind turbine blade described herein facilitate operation of a wind turbine system. Specifically, the wind turbine blade assembly as described above facilitates erosion resistance and aerodynamic performance. Therefore, the robust, wear-resistant assembly facilitates blade reliability, reduced maintenance costs and wind turbine system outages. Also, the blade fabrication methods described above facilitates reducing adhesive usage and wastage while mitigating any impact to overall blade fabrication time and costs. Specifically, such costs include substantially eliminating production floor use for prefabrication of bond caps independent of the remainder of the blade components. Moreover, blade labor and material production costs are reduced or eliminated. Furthermore, an effectiveness of forming the blade is improved by facilitating a mitigation of void formation and component misalignment.
Exemplary embodiments of wind turbine blade assemblies as associated with wind turbine systems are described above in detail. The methods, apparatus and systems are not limited to the specific embodiments described herein nor to the specific illustrated wind turbine blade assemblies.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
