Wind turbine blades with improved bond line and associated method
A wind turbine blade includes an upper shell member and a lower shell member with an internal cavity therebetween. The shell members are joined at leading and trailing edges of the blade with a bond paste along a bond line having a designed width. A sleeve is disposed within the internal cavity between the upper and lower shell members along at least one of the leading or trailing edges, with the bond paste contained within the sleeve. The sleeve has a closed end that is impermeable to the bond paste and opposite sides that are permeable to air and permeable to the bond paste. The bond past adheres to the upper and lower shell members through the sleeve sides and the closed end of the sleeve defines the design width of the bond line in the internal cavity.
1. A wind turbine blade, said blade comprising:
an upper shell member and a lower shell member;
said upper shell member and said lower shell member defining an internal cavity therebetween and joined at leading and trailing edges of said blade with a bond paste along a bond line having a designed width; and,
a sleeve disposed within said internal cavity between said upper and lower shell members along at least one of said leading or trailing edges, said bond paste contained within said sleeve, said sleeve comprising a closed end that is substantially impermeable to said bond paste, said sleeve comprising opposite sides that are permeable to air and permeable to said bond paste;
wherein said bond past adheres to said upper and lower shell members through said sleeve sides, said closed end of said sleeve defining said design width of said bond line in said internal cavity.
2. The wind turbine blade as in claim 1 , wherein said sleeve sides are formed of an open weave mesh material.
3. The wind turbine blade as in claim 1 , wherein said sleeve sides and said sleeve closed end are formed of different materials, said sleeve sides joined to said closed end.
4. The wind turbine blade as in claim 1 , wherein said sleeve sides and said sleeve closed end are formed from a common base material, said closed end treated with a permeability reducing material.
5. The wind turbine blade as in claim 4 , wherein said permeability reducing material comprises a coating applied to said base material.
6. The wind turbine blade as in claim 4 , wherein said permeability reducing material comprises an additional material layer applied to said base material.
7. The wind turbine blade as in claim 1 , wherein said sleeve sides are formed of an open weave mesh material having an adhesive resin applied thereto.
8. The wind turbine blade as in claim 1 , wherein said sleeve closed end has a stiff, pre-formed shape and said sleeve sides are formed of a pliant material that conforms to inner contours of said upper and lower shell members.
9. The wind turbine blade as in claim 1 , further comprising an adhesive resin applied to said upper and lower shell members to aid in adhering said sleeve sides to said shell members.
10. The wind turbine blade as in claim 1 , wherein said sleeve is applied along said trailing edge.
11. The wind turbine blade as in claim 1 , wherein said closed end of said sleeve is permeable to air.
12. The wind turbine blade as in claim 1 , wherein said sleeve is initially slidable within said internal cavity against said upper and lower shell members, and is configured for being pulled towards said leading or trailing edge to bring said closed end to said design width of said bond line.
13. A method for forming a bond between upper and lower shell members along at least one of the leading or trailing edges of a wind turbine blade, said method comprising:
placing an amount of bond paste into a sleeve, the sleeve having a closed end that is substantially impermeable to the bond paste and sides that are permeable to the bond paste;
placing the sleeve into one of the shell members either before or after the bond paste has been placed in the sleeve such that the closed end extends into the shell member and the ends of the sleeve sides extend from the shell member;
anchoring the sleeve ends to prevent movement of the closed end relative to the shell member; and,
joining the shell members together along the leading and trailing edges such that the sleeve is compressed and the bond paste permeates through the sleeve sides and bonds to the shell members while the closed end of the sleeve limits migration of the bond paste into the blade past a design bond width while still allowing the escape of air through the closed end.
14. The method as in claim 13 , further comprising trimming excess bond paste that migrated out from the leading or trailing edge.
15. The method as in claim 14 , further comprising measuring the amount of excess bond paste trimmed from the leading or trailing edge and reducing the amount of bond paste initially placed into a subsequent sleeve by the measured amount of trimmed bond paste.
16. The method as in claim 13 , wherein the sleeve is applied along the trailing edge.
17. The method as in claim 13 , further comprising applying an adhesive resin to the sleeve sides.
18. The method as in claim 13 , further comprising applying an adhesive resin to the upper and lower shell members to further aid in attachment of the sleeve sides to the shell members.
19. The method as in claim 13 , further comprising forming the closed end of the sleeve into a stiff, pre-formed shape prior to placing the bond paste into the sleeve.
20. The method as in claim 13 , further comprising initially placing the sleeve between the shell members such that the closed end extends beyond the design bond width and pulling the sleeve towards the leading or trailing edge to bring the closed end to the design bond width prior to anchoring the sleeve ends.