Patent Application
20150176421
This application claims the benefit, under 35 U.S.C. §119, of EP 13199025.1, filed Dec. 20, 2013, the disclosure of which is incorporated herein by reference in its entirety.
The invention relates to a turbine engine guide vane assembly. More specifically, the invention relates to a turbine engine compressor guide vane assembly fitted with an internal collar having a gasket ensuring airtightness with a casing of the turbine engine. The invention likewise relates to a turbine engine having a gasket disposed between a collar and a casing of the turbine engine.
A turbojet engine comprises a plurality of compartments such as a fan, compressors, a combustion chamber and turbines. These compartments are fixed to the intermediate casing, such that they are all connected. The intermediate casing is crossed by annular flows that circulate in the turbine engine. In order to limit leaks, sealing devices are provided at the interfaces between the intermediate casing and the compartments. In particular, the low-pressure compressor which is fixed directly to the intermediate casing exhibits gaskets at its external casing and at the internal collar of its downstream guide vane assembly.
The internal collar of the upstream guide vane assembly is fixed to the internal ends of the blades and cooperates in an airtight manner with a planar surface of the intermediate casing. To this end, the guide vane assembly comprises a circular silicon gasket pressed against the sealing surface of the casing.
Document EP 1 426 559 A1 discloses an inner collar for the guide vane assembly of a low-pressure axial turbojet engine compressor. The compressor is fixed to the intermediate casing of the turbine engine, the internal collar of the last stage of the compressor being in contact with the intermediate casing by means of a circular gasket. During operation of the turbojet engine, the circular gasket is subject to vibrations due, for example, to the operation of the turbine engine itself, to ingestion, to a pumping phenomenon, to the existence of an unbalancing mass or to a “fan blade off” state. These vibrations deform the gasket radially and axially, thereby reducing the airtightness. The gasket may likewise become detached from the intermediate housing, thereby creating a leak. The gasket no longer achieves either its contact pressure or its nominal position.
The object of the invention is to solve at least one of the problems presented by the prior art. More precisely, the invention aims to preserve the airtightness of a guide vane assembly at the junction between its internal collar and a sealing surface of a casing when the guide vane assembly is subject to turbine engine vibrations.
The invention relates to a guide vane assembly of an axial turbine engine compressor, the guide vane assembly comprising an annular row of blades which extend radially, an internal collar disposed at the internal ends of the blades which comprises a circular gasket on one of the upstream or downstream sides of the collar, so as to ensure airtightness with a sealing surface of an intermediate casing of the turbine engine, this being exceptional in that the internal collar comprises a cavity in which the gasket is housed.
According to various embodiments of the invention, the cavity is formed, in various embodiments integrally, in the material of the internal collar. In various embodiments the collar can be realized in a polymer material, for example, in a composite material with an organic matrix.
According to various embodiments of the invention, the cavity is formed by a portion of the collar and one or a plurality of members added to the collar and, in various embodiments, creating a generally circular form, the internal collar and each added member can be realized in composite materials with an organic matrix.
According to various embodiments of the invention, the guide vane assembly comprises a hook which forms the cavity, so as to hold the gasket against the sealing surface of the casing and against the internal collar, the cavity can form an annular throat essentially opened axially.
According to various embodiments of the invention, the guide vane assembly comprises an annular shoulder delimiting the cavity axially, in various embodiments the shoulder can be formed by an annular flange extending radially, the annular shoulder can be formed by the annular collar and/or by each added member.
According to various embodiments of the invention, the guide vane assembly comprises a generally tubular face delimiting the inside of the cavity radially, the tubular face can be formed on the annular collar and/or on each added member, in various embodiments at least one added member tubular face compresses the gasket radially against the internal surface of the internal collar.
According to various embodiments of the invention, the gasket can be disposed axially and/or radially inside the cavity, in various embodiments the gasket can comprise an elastomer material such as a silicon material.
According to various embodiments of the invention, the gasket exhibits a generally toroidal form, the revolution profile of the gasket preferably generally being a circle, a triangle or a quadrilateral such as a parallelogram.
According to various embodiments of the invention, the gasket guarantees airtightness between the internal collar and each added member, for example around the internal collar.
According to various embodiments of the invention, each added member is fixed to the internal collar, each added member can be interlocked or bonded adhesively to the internal collar or fixed to the blades with the help of fixing means by material engagement.
According to various embodiments of the invention, each added member extends over most of, e.g., over all, the axial length of the internal collar, each added member preferably being placed against the internal surface of the internal collar.
According to various embodiments of the invention, the length of the internal collar is more than twice the chord of each blade measured according to the chord, the length of each added member can be greater than the chord of each blade measured according to the chord.
According to various embodiments of the invention, the guide vane assembly comprises an annular layer of abradable material disposed on the upstream or downstream side of the internal collar which is axially opposed to that which the circular gasket comprises, the abradable layer can extend axially up to the material delimiting the cavity.
According to various embodiments of the invention, the internal collar and at least one added member are realized in, e.g., constructed/fabricated of, different materials, the density of each added member can be lower than the density of the internal collar.
According to various embodiments of the invention, each added member is fixed to the internal collar with the help of fixing means by material engagement and/or each added member fits closely against the internal surface of the internal collar.
According to various embodiments of the invention, the tubular face is disposed axially and/or radially to the inside of the external surface of the internal collar.
According to various embodiments of the invention, the gasket extends axially beyond the internal collar and/or each added member.
According to various embodiments of the invention, the abradable layer is delimited axially with the help of the internal collar and/or by each added member.
According to various embodiments of the invention, the gasket fits closely against most of the internal surface of the cavity, in various embodiments against all of it, and/or the gasket fills most of the internal volume of the cavity.
The invention likewise relates to an axial turbine engine comprising a casing provided with a sealing surface, at least one compressor with a guide vane assembly that cooperates in an airtight manner with the sealing surface, this being exceptional in that the guide vane assembly conforms to the invention, in various embodiments the gasket can be compressed axially between the guide vane assembly and the sealing surface of the casing.
According to various embodiment of the invention, axial play J is conserved between the casing and the internal collar, the gasket extending axially over the entire axial play J, the turbine engine can comprise at least one turbine, at least one fan, the casing being the intermediate casing of the turbine engine, and withstands most, possibly all, of the forces of each compressor, each turbine and each fan.
The invention allows the gasket to be effectively held against the sealing surface of the casing. The cavity allows the gasket to be housed and held against the casing surface. The solution in which the cavity is integrally formed in the material of the internal collar allows a simple collar to be realized integrally. The collar can be realized by grinding, its cavity can be ground directly and/or fabricated, which enables production costs to be kept down.
Due to the added member, a radial compressive stress can be applied to the gasket, which further improves the seal. The added member allows the gasket to be supported, it forms a support improving positioning, the gasket holding position. It further allows the contact between the gasket and the casing to be made rigid. The added member improves the rigidity of the internal collar and limits its axial and/or radial deformation, such as its out-of-roundness, significantly. The addition of the added member enables a cavity with a complex form to be realized without increasing the production cost of the internal collar.
The added member allows the lightness of the guide vane assembly to be preserved. In fact, it can be realized in a lighter material than the internal collar. For example, the internal collar can be realized in metal and the added member perhaps in a polymer, such as a composite material.
During production of the turbine engine, the compressor is assembled so as to form an assembly which is then placed against the intermediate casing. At this point the circular gasket is compressed axially against the sealing surface of the turbine engine casing. The compression of the gasket relies on a series of sides including a plurality of members including the blades of the guide vane assembly. The blades can exhibit variations in position of more than 2.00 mm, which increases the margin that the circular gasket must be able to tolerate. Moreover, the circular gasket must likewise be adapted to a differential dilatation phenomenon.
In the following description, the terms “interior” or “internal” and “exterior” or “external” relate to a position in respect of the axis of rotation of an axial engine turbine. The axial direction relates to the axis of rotation.
During operation, the mechanical power of the turbine 10 transmitted via the central shaft up to the rotor 12 sets the two compressors 4 and 6 in operation. Gear reduction means or concentric shafts can connect the turbines 10 to the compressors 4 and 6. The compressors 4 and 6 comprise a plurality of rows of rotor blades 24 associated with rows of stator blades 26. The rotation of the rotor 12 about its axis of rotation 14 thereby allows an air flow rate to be generated and progressively compressed up to the inlet of the combustion chamber 8, in order to increase the output of the turbine engine.
An input blower usually referred to as a fan 16 is coupled with the rotor 12 and generates an air flow that divides up into a primary flow 18 crossing the different levels of the turbine engine mentioned above and a secondary flow 20 crossing an annular conduit (partially represented) along the engine, after which it joins up with the primary flow again at the turbine outlet. The turbine engine 2 can comprise a plurality of fans. The primary and secondary flows 18 and 20 are annular flows and are channeled through the casing of the turbine engine 2.
The turbine engine 2 can comprise a casing, possibly an intermediate casing. The intermediate casing guarantees a fixing structure function to which the compressors 4 and 6, the turbines 10, the combustion chamber 8, the fan 16 and the shafts are all fixed or connected, so that at least most of the forces, in various embodiments all of the forces, coming from it are withstood.
The low-pressure compressor 4 comprises a plurality of guide vane assemblies, in this case four, which each contain a row of stator blades 26. The stator blades 26 extend essentially radially from an exterior casing 28 and can be fixed there with the help of an axle. They are regularly spaced relative to one another and exhibit the same angular orientation in the flow. The guide vane assemblies are linked to the fan 16 or to a row of rotor blades 24 to guide the flow of air, so as to convert the flow speed into pressure.
The blades 24 in the same row are advantageously identical. The space between the blades 24, just as their angular orientation, can vary locally. Certain blades 24 can differ from the rest of the blades 24 in their row.
Each guide vane assembly comprises an internal collar 30 which is disposed at the internal ends of the stator blades 26 of the corresponding row. The internal collars 30 allow the primary flow 18 to be guided during its compression. They likewise allow the ends of the blades 26 to be held in relation to one another. The guide vane assemblies can likewise comprise annular layers of abradable material 32, that can be applied to each internal surface of the internal collar 30. These abradable layers 32 cooperate by abrasion with radial annular ribs of the rotor 12, in order to guarantee its airtightness.
Downstream, the compressor can be mounted, e.g., directly, on the casing of the turbine engine, for example, on the intermediate casing 34. The compressor can be mounted on any casing or any portion of the turbine engine casing. The compressor can be in contact with the intermediate casing 34 at its exterior casing 28 and at the downstream side of the internal collar 30 of its downstream guide vane assembly. Annular seals are provided for at the interfaces.
In various embodiments, the internal collar 30 comprises an annular gasket 36 or a circular gasket 36 which ensures airtightness with a sealing surface of the casing, for example, the intermediate casing 34 of the turbine engine 2. The gasket 36 can form a sealing bead and can comprise, for example, for the most part or in its entirety, an elastomer material such as a silicon material. The silicon material can be organic or made of resin. The gasket 36 can be disposed at an opposite axial end to that receiving the abradable layer 32.
The intermediate casing 34 can be crossed by the primary flow 18, it guides it with the help of an external wall 38 and an internal wall 40 which are linked by casing arms 41 which cross the flow radially. The internal wall 40 can be formed by an internal hub 42 to which shafts of the turbine engine can be articulated. Axially in respect of the gasket 36 of the internal collar 30, the casing comprises a sealing surface 44, generally planar for example, in order to reduce rubbing in the case of axial vibration and to avoid hyperstatic assembly. The sealing surface 44 can be substantially conical.
The internal collar 30 comprises a cavity 45 in which is housed the gasket 36, for the most part or completely, for example. The cavity 45 can be circular. The cavity 45 can be formed, e.g., integrally, in the material of the internal collar 30. The cavity 45 can run around the collar 30 or be formed in a discontinuous manner. The cavity 45 can form a hook, it can be open essentially axially towards the sealing surface 44 of the casing 34. The cavity 45 can exhibit a general U-shaped profile pivoted towards the casing 34. The cavity 45 and the sealing surface 44 envelop the gasket 36 for the most part or essentially completely. They can enclose it on at least four faces.
The internal collar 30 can comprise one or a plurality of added members 46. The added member or members 46 extend along the circular gasket 36 following its circumference. Each added member 46 can exhibit a generally circular or annular form, the combination of added members 46 being generally circular. Each added member 46 can be disposed inside the internal collar 30 and can hold the circular gasket 36, in various embodiments against the internal surface of the collar 30 and/or against the intermediate casing 34. Each added member 46 can apply an axial and/or radial pressure against the circular gasket 36, possibly in such a manner as to increase the axial length of the gasket 36 following compression.
The cavity 45 can be formed by combining a portion of the internal collar 30 and of the added member or members 46, the cavity 45 exhibiting a circular continuity. Alternatively, the added members 46 can be inserted in the discontinuous portions of the internal collar 30, so as to form a generally continuously circular cavity 45.
The guide vane assembly can comprise a shoulder 48. The shoulder 48 can be formed on the internal collar 30 and/or on each added member 46. Each shoulder 48 extends radially, is in contact with the circular gasket 36 and can form an axial stop for the circular gasket 36. The shoulder 48 or the combination of shoulders can possibly extend over most or all of the radial thickness of the circular gasket 36. At least one or every shoulder 48 can be an annular flange extending radially. Each added member 46 can be fixed to the internal radial end of the shoulder of the internal collar 30, by adhesive bonding for example. When the internal collar 30 and each added member 46 each exhibit a shoulder, these are radial to one another in the extension. The added member 46 can allow the circular gasket 36 to be held axially.
The guide vane assembly can comprise a generally tubular or substantially conical face 50 which is possibly disposed axially and/or radially to the inside of the internal collar 30. The tubular face 50 can extend over the majority, in various embodiments over substantially the entirety, of the axial thickness of the circular gasket 36, this applying around the gasket. The tubular face 50 can be formed on the internal collar 30 and/or on each added member 46. It can exhibit material discontinuities and be both formed by the collar 30 and also by the added member or members 46.
The circular gasket 36 can be added and adhesively bonded to the internal collar 30 or realized in the cavity and adhered there. The gasket 36 can exhibit a ring or toroidal form, it can exhibit a generally round or polygonal revolution profile. It can exhibit a revolution profile in triangular, quadrilateral—such as a parallelogram—or square form. The gasket 36 can guarantee airtightness between the internal collar 30 and each added member 46.
The internal collar 30 can comprise an annular partition 52 with a generally constant thickness, for example. The partition's 52 revolution profile can be inclined relative to the axis of rotation of the turbine engine 2, for example by at least 5°, for example by at least 10°, for example by at least 15°. The internal collar 30 can comprise an annular row of openings (not shown) into which are introduced the internal ends of the blades 26 in order to fix them. The internal collar 30 forms an axial annular junction between a portion of rotor and the intermediate casing 34. The internal collar's 30 length is greater than 130%, for example greater than 250%, of the chord of the stator blade 26, both measured according to the chord at the junction between the stator blade 26 and the internal collar 30.
Axial play J is conserved between the sealing surface 44 of the casing 34 and the internal collar 30. In various embodiments, the same equal axial play is conserved between the sealing surface 44 of the casing and each added member 46. The circular gasket 36 extends axially right along the play J, so as to form an airtight barrier. The material of the gasket 36 likewise enables a cushioning of vibrations at the axial play J to be guaranteed.
At least one or each added member 46 can be fixed to the internal collar 30, for example by adhesive bonding and/or by interlocking. Each added member 46 can comprise an annular platform 54 fitting closely against the inside of the partition 52 of the internal collar 30. The internal collar 30 and/or each added member 46 and/or the blades 26 can comprise fixing means by material engagement, resulting in the fixing of each added member 46 on the internal collar 30 and/or on the blades 26, the internal collar 30 likewise being able to be fixed to the blades 26 by these means.
The internal collar 30 and/or each added member 46 can be realized in, e.g., constructed/fabricated, of metal such as titanium or aluminium. The internal collar 30 and/or each added member 46 can be realized, e.g., constructed/fabricated, by injection of a polymer or a filled resin. At least one, in various embodiments both, of these can be realized, e.g., constructed/fabricated, in composite materials with an organic matrix. They can comprise a polyetherimide (PEI) or polyether ether ketone (PEEK) matrix. They can comprise carbon fibers, glass fibers, graphite fibers. The fibers can exhibit a length of less than 3.00 mm, for example less than 1.00 mm, for example less than 0.30 mm. At least one of these members can comprise a fibrous preform with an epoxy matrix.
The invention can likewise be applied to a high-pressure compressor, for example an internal collar of a guide vane assembly upstream of the high-pressure compressor. In this configuration, the upstream guide vane assembly comprises an elastomer gasket disposed upstream of its internal collar, the gasket cooperating with a sealing surface of the downstream face of the intermediate casing of the turbine engine. The gasket is likewise held against the collar and the sealing surface with the help of at least one added member.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13199025.1 | Dec 2013 | EP | regional |
