Patent Grant
8182213
The application relates generally to vane assemblies for gas turbine engine and, more particularly, to such vane assemblies where the vanes are removable therefrom.
A known type of vane assemblies for gas turbine engines in which the vanes are removable includes vanes inserted through holes in a casing and retained by a circumferential strap extending around the casing. Such a retention method has uneven vane retention force around the circumference that is undesirable in high thrust engines. In addition, the strap is generally disengaged from the casing when a vane needs to be replaced, thus at the same time disengaging and shifting the remaining vanes out of position.
In one aspect, there is provided a vane assembly for a gas turbine engine, the assembly including concentric annular inner and outer shrouds with a plurality of vanes extending therebetween, each vane being connected to at least one adjacent portion of at least one of the inner and the outer shrouds through a melt-weld connection, the melt-weld connection including non-metallic heat-meltable material with a metal wire mesh layer trapped therein, the metal wire mesh being heatable to melt the heat-meltable material for formation and breakdown of the melt-weld connection.
In another aspect, there is provided a vane assembly for a gas turbine engine, the assembly comprising an annular inner shroud, an annular outer shroud concentric with the inner shroud, and a plurality of vanes extending between the inner and outer shrouds, each vane including a vane root connected to the outer shroud by a melt-weld connection, the melt-weld connection including a non-metallic heat-meltable material in contact with the vane root and the outer shroud, the melt-weld connection including a metal wire mesh layer trapped in the material.
In another aspect, there is provided a method of assembling a vane assembly of a gas turbine engine, the assembly including concentric annular inner and outer shrouds with a plurality of vanes extending therebetween, the method comprising providing a non-metallic heat-meltable element between each vane and at least one adjacent portion of at least one of the inner and outer shrouds, the element including a metal wire mesh therein, and using the metal wire mesh to heat and melt the element until formation of a melt-weld connection between each said vane and the at least one adjacent portion.
In a further aspect, there is provided a method of removing a vane assembly of a gas turbine engine, the method comprising heating a melt-weld connection between a vane and at least one adjacent portion of at least one of inner and outer shrouds of the vane assembly using wire mesh trapped within the connection, and pulling the vane out of engagement with the at least one adjacent portion when the connection is sufficiently softened.
Reference is now made to the accompanying figures in which:
Referring to
A plurality of vanes 28 extend radially between the inner and outer shrouds 22, 24 downstream of the rotor blades. The vanes 28 are preferably made of an adequate type of metal, for example an adequate type of aluminum alloy, titanium alloy or ferrous alloy. Each vane 28 has a vane root 30 retained in the outer shroud 24, a vane tip 32 retained in the inner shroud 22, and an airfoil portion 34 extending therebetween. The airfoil portion 34 of each vane 28 defines a leading edge 36 and a trailing edge 38, such that an airflow coming from the blades and passing through the vane assembly 20 flows over the vane airfoil portion 34 from the leading edge 36 to the trailing edge 38.
The vane root 30 comprises an end platform 40 defining an inner pressure surface 42 and an opposed outer surface 44. The outer shroud 24 has an inner surface 46 delimiting the flow path 26 and an outer pressure surface 48 opposite thereto. Vane-receiving openings 50 are defined through the outer shroud 24 and are regularly distributed about the circumference thereof. Each opening 50 has a shape generally corresponding to the shape of the vane 28 radially inwardly of and adjacent to the end platform 40, and is configured such that the vane 28 can be inserted therethrough from the tip 32 while the platform 40 is prevented from passing therethrough.
The inner shroud 22 has an outer surface 52 delimiting the flow path 26 and an inner surface 54 opposite thereto. Vane-receiving openings 56 are defined through the inner shroud 22 and are regularly distributed about the circumference thereof. Each opening 56 is configured such that the tip 32 of the vane 28 can be inserted therethrough and retained with a bonded grommet 58 extending around the tip 32 within the opening 56.
Each vane 28 is connected to adjacent part(s) of the inner and/or the outer shrouds through a melt-weld connection, which is preferably a thermoplastic melt-weld connection. In the embodiment shown, each vane is connected both to the outer shroud 24 and to the inner shroud 22, with the melt-weld connection between each vane 28 and the outer shroud 24 being provided by a melt-weld joint 60 and a melt-weld retainer ring 62, and the melt-weld connection between each vane 28 and the inner shroud 22 being provided by melt-weld brackets 64. Alternately, only one or any two of these connections can be used.
The melt-weld joint 60 is located between, and interconnects, the inner pressure surface 42 of the end platform 40 and the outer pressure surface 48 of the outer shroud 24. In the embodiment shown, the joint 60 includes a first layer 66 of non-metallic heat-meltable material located against the outer surface 48 of the outer shroud 24, a second layer 68 of metal wire mesh, and a third layer 70 of non-metallic heat-meltable material located against the inner pressure surface 42 of the vane platform 40. The heat-meltable material is preferably a thermoplastic material, which may be fiber reinforced. The metal wire mesh of the second layer 68 is used to heat the heat-meltable material, for example through induction heating or resistance hearing, until the material is sufficiently melted to form a connection between the inner and outer pressure surfaces 42, 48. The inner pressure surface 42 and/or the outer pressure surface 48 may include an adequate primer layer to enhance the strength of the bond between the surface and the melt-weld joint 60.
The retainer ring 62 extends over the outer surfaces 44 of the end platforms 40 of the vanes 28, and over portions of the outer shroud 24 extending between adjacent end platforms 40. The end platforms 40 are thus sandwiched between the retainer ring 62 and the outer shroud 24. The retainer ring 62 is made of a continuous film and may include one or several layers of material. In the embodiment shown, the retainer ring 62 includes a first layer 72 of non-metallic heat-meltable material extending over the end platforms 40, a second layer 74 of metal wire mesh over the first layer 72, an optional third layer 76 of fiber or fabric, and a fourth layer 78 of non-metallic heat-meltable material extending over the third layer 76 or over the second layer 74 if the third layer 76 is omitted. The non-metallic heat-meltable material is preferably a thermoplastic material which may be fiber reinforced, such as for example a fiber impregnated thermoplastic film, or which may be in the form of a neat resin thermoplastic film. The fiber or fabric layer 76, including for example dry fiber fabric or dry fiber unidirectional tape, is preferably used in combination with the first layer 72 and/or the fourth layer 78 being made of a neat resin thermoplastic film. The metal wire mesh of the second layer 74 is used to heat the heat-meltable material, for example through induction heating or resistance hearing, until the heat-meltable material is sufficiently melted to form the retainer ring 62. A vacuum bag, heat shrink tape or contact pressure (not shown) may be used to apply pretension to the vane and shroud during formation of the retainer ring 62, and/or shaped dampers may be melt-welded to the retainer ring 62 at the same time to provide vibration damping to the vanes.
The melt-weld brackets 64 extend from each side of the tip 32 to the inner surface 54 of the inner shroud 22. In the embodiment shown, each bracket 64 includes a first layer 80 of non-metallic heat-meltable material extending in contact with the vane tip 32 and the inner surface 54 of the inner shroud, an optional second layer 82 of fiber or fabric extending over the first layer 80, a third layer 84 of metal wire mesh extending over the second layer 82 or over the first layer 80 if the second layer 82 is omitted, and a fourth layer 86 of non-metallic heat-meltable material extending over the third layer 84. The non-metallic heat-meltable material is preferably a thermoplastic material, which may be fiber reinforced or may also be in the form of a neat resin thermoplastic film. The metal wire mesh of the third layer 84 is used to heat the heat-meltable material, for example through induction heating or resistance heating, until the material is sufficiently melted to form the melt-weld connection between the vane tip 32 and the inner shroud 22.
Other heating sources may be used to heat the heat-meltable material of the melt-weld connections (melt-weld joints 60, retainer ring 62 and/or brackets 64) in addition to or in replacement of heating with the metal wire mesh layers 68, 74, 84, such as for example ultrasonic friction melding, or the use of a heat gun, hot air jet and/or a laser.
The melt-weld connection between each vane 28 and the adjacent portion(s) of the inner and/or outer shrouds 22, 24 thus allows the vanes 28 to be removed by heating the melt-weld connections (e.g. the melt-weld joint 60, at least the portion of the retainer ring 62 overlapping the vane 28, the melt-weld brackets 64) between the vane 28 and the adjacent portion(s) of the inner and/or outer shrouds 22, 24, for example using the wire mesh trapped within each melt-weld connection, until the connection is sufficiently softened for the vane to be disengaged from a remainder of the assembly. The wire mesh layer 68, 74, 84 of each connection allows for the heating to be localized around the vane 28 that is to be removed, such as to limit the repair work required once the vane is replaced. In cases where the heat-meltable material is a thermoplastic material that is fiber-reinforced and/or when fiber or fabric layers are present, the fibers preventing the vane from being pulled out are cut prior to removing the vane from the assembly.
A replacement vane can be installed using the above-described method, including providing a heat-meltable element between the vane and each adjacent portion of the inner and/or the outer shroud to which the removed vane was connected, and heating the element, for example through a wire mesh layer embedded therein, until formation of a melt-weld connection such as the melt-weld joint 60, the retainer ring 62 and/or the melt-weld brackets 64. When a retainer ring 62 is present, the cut-out portion of the retainer ring 62 which was removed prior to removing the vane is mended after installation of a new vane by forming a new retainer ring portion over the new vane, for example by overlapping layers of the heat-meltable material, such as a thermoplastic film (with or without fibers), over the cut out portion, and heating until the melt-weld connection of the retainer ring is restored.
As such, installation, refurbishment and replacement of the vanes are facilitated.
Referring to
The vanes 128 are interconnected such as to define groups or packs 121 of multiple vanes, each pack 121 defining an angular portion of the vane assembly. Each vane 128 within a pack 121 is connected to adjacent portions of the inner and the outer shrouds, which are defined by the inner and outer shroud portions 122, 124 of the adjacent vane(s), through a melt-weld connection. The melt-weld connection between the inner shroud portions 122 of the vanes 128 of a pack 121 is provided by one or more layers 158 of heat-meltable material, for example thermoplastic material which may be fiber reinforced, extending over the inner surface 154 of the inner shroud portions 122. The melt-weld connection between the outer shroud portions 124 of the vanes 128 of a pack 121 is provided by one or more layers 162 of heat-meltable material, for example thermoplastic material which may be fiber reinforced, extending over the outer surface 148 of the outer shroud portions 124. As such, the vanes 128 within a pack 121 are interconnected while allowing for one or more vanes 128 of a pack 121 to be replaced, through heating and softening of the heat-meltable material layers 158, 162 retaining the vane to the adjacent vane(s), as above. A wire mesh layer may be trapped within the heat-meltable material layers 158, 162 to facilitate heating thereof for formation and breakdown of the melt-weld connection.
The vane assembly may be assembled using meld-weld connections between the vane packs 121, for example using a retainer ring as described in the previous embodiment.
A number thermoplastics may be used as the heat-meltable material for forming the melt-weld connection between the outer shroud portions of the vanes, for example polyphenylene sulphide (PPS), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyamideimide (PAI), polysulfone (PSU) and/or polyphthalamide (PPA).
The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For example, the melt-weld connection can be provided in alternate geometries and/or with a different number of layers including a single layer and/or with vanes made of fibre reinforced thermoset polymer materials, or of hybrid metal-fibre reinforced thermoset polymer materials. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20100272565 A1 | Oct 2010 | US |
