EP3444443A1 - Abradable seal composition for a turbine engine compressor - Google Patents

Abstract

The subject of the invention is a composition for an abradable gasket (36) for a turbomachine, in particular a powder, said gasket (36) being able to crumble in the event of contact with a rotor of said turbomachine. The seal is formed on the arcuate wall (30) of a support housing (28). The composition comprises: a majority metal phase with a majority of aluminum and chromium, a second minority phase comprising a mineral material and / or an organic material. The subject of the invention is also a method for producing an abradable gasket (36) for a turbomachine, in particular for a low-pressure compressor of the turbojet engine, also known as a booster.

Description

Technical area

The invention relates to the field of turbomachine sealing by two-phase abradable seal. The invention also proposes a method for producing an abradable seal. The invention also relates to a compressor and an axial turbomachine, in particular an aircraft turbojet engine or an aircraft turboprop engine.

Prior art

The mechanical clearances between the rotor blade heads and the casing surrounding them imply leaks limiting the performance of a turbomachine compressor. In order to reduce these leaks, it is imperative to bring the vanes closer to the casing while maintaining a safety margin. Indeed, in case of contact the blades as the housing can be damaged, and jeopardize the operational safety of the turbomachine. These cases are commonplace because of vibrations, ingestions, centrifugal force, expansion, and rotor offsets in particular. Therefore, adding a layer of abradable material to the interface between the housing and the blades can control the damage in case of contact since the degradation is concentrated in the material of the seal that crumbles.

The document EP3023511A1 discloses a composition for an abradable turbine engine seal, the composition comprising an aluminum base, nickel powder, polyester powder. It also teaches an external compressor casing of low-pressure axial turbomachine with an abradable seal surrounding an annular row of rotor blades. The seal comprises a rounded support covered with a layer of abradable material comprising a metal phase mainly aluminum, and with nickel in less proportion. The abradable further comprises 25% and 55% of additive, such as polyester, methyl methacrylate, hexagonal boron nitride, calcium fluoride. The support is segmented, and forms an outer casing organic matrix composite of the compressor. However, the characteristics of such a seal are perfectible. Moreover, the application of the joint remains complex.

The document EP 1 428 600 discloses an abradable with an organic / inorganic phase and a metal phase of aluminum. The particular mechanical characteristics of such a seal are perfectible.

Summary of the invention Technical problem

The object of the invention is to solve at least one of the problems posed by the prior art. More specifically, the invention aims to optimize the friable character of the seal. The invention also aims to provide a simple solution, resistant, lightweight, economical, reliable, easy to produce, convenient maintenance, easy inspection, and improving performance.

Technical solution

The subject of the invention is a composition according to claim 1.

• La phase métallique comprend en masse de 20% jusqu'à 45% de chrome.
• Le matériau polymère comprend du polyester et le matériau organique comprend nitrure de bore hexagonal.
• La phase métallique représente de 50% à 90% de la masse de la composition.
• La phase métallique représente de 82% à 90% de la masse de la composition.
• La deuxième phase représente de 10% à 50% de la masse de la composition.
• La deuxième phase représente de 10% à 25% de la masse de la composition.
• La deuxième phase comprend au moins un des matériaux suivant : le polyimide, le polyamide-imide, le polyéther-imide, le bismaléimide, du fluoroplastique, une résine à base de cétone, des cristaux liquides de polymères ; ou toutes leurs combinaisons.
• La deuxième phase comprend au moins un des matériaux suivant : le disulfure de molybdène, le graphite, le talc, la bentonite, le mica ; ou toutes leurs combinaisons.

According to advantageous embodiments of the invention, the composition may comprise one or more of the following characteristics, taken separately or according to all the possible technical combinations:

• The metal phase comprises in mass of 20% up to 45% of chromium.
• The polymeric material comprises polyester and the organic material comprises hexagonal boron nitride.
• The metal phase represents from 50% to 90% of the mass of the composition.
• The metal phase represents from 82% to 90% of the mass of the composition.
• The second phase represents from 10% to 50% of the mass of the composition.
• The second phase represents from 10% to 25% of the mass of the composition.
• The second phase comprises at least one of the following materials: polyimide, polyamide-imide, polyether-imide, bismaleimide, fluoroplastic, a ketone-based resin, liquid crystal polymers; or all their combinations.
• The second phase comprises at least one of the following materials: molybdenum disulfide, graphite, talc, bentonite, mica; or all their combinations.

According to another embodiment, the subject of the invention is a composition for an abradable gasket of a turbomachine, in particular a powder, said gasket being capable of crumbling in the event of contact with a rotor of said turbomachine, the composition comprising a metal phase with a mass majority of aluminum, a second phase comprising a mineral material and / or an organic material; remarkable in that the metal phase represents between 80% and 90% of the mass of the composition, and / or represents at least 81%, or 82% or 83% of the mass of the composition. According to another embodiment, the subject of the invention is a composition for an abradable gasket of a turbomachine, in particular a powder, said gasket being capable of crumbling in the event of contact with a rotor of said turbomachine, the composition comprising a metal phase with a mass majority of aluminum, a second phase comprising a mineral material and / or an organic material; remarkable in that the mineral material represents: from 10% up to 45%, or from 10% up to 25% of the mass of the composition.

According to another embodiment, the subject of the invention is also a composition for an abradable gasket of a turbomachine, in particular a powder, said gasket being capable of crumbling in the event of contact with a rotor of said turbomachine, the composition comprising: a metal phase with a mass majority of aluminum, a second phase comprising a mineral material and / or an organic material; remarkable in that the organic material represents: from 10% up to 45%, or from 10% up to 25% of the mass of the composition.

According to another embodiment, the subject of the invention is also a composition for an abradable gasket of a turbomachine, in particular a powder, said gasket being capable of crumbling in the event of contact with a rotor of said turbomachine, the composition comprising: a metal phase with a mass majority of aluminum, a second phase; remarkable in that the second phase comprises at least one of the following materials: polyimide, polyamide-imide, polyether-imide, bismaleimide, fluoroplast, a ketone-based resin, liquid crystals of polymers, disulfide of molybdenum, graphite, talc, bentonite, mica; or any feasible combination.

The subject of the invention is also a compressor, a turbomachine, in particular a low-pressure turbomachine compressor, comprising a rotor with rotor blades and an abradable seal cooperating in a sealed manner with said rotor blades, remarkable in that the abradable seal comprises a composition according to the invention.

• Le compresseur comprend une paroi composite à matrice organique sur laquelle est disposé le joint abradable, et une interface entre la paroi et le joint abradable qui est formée par un feuillard métallique.
• Les aubes rotoriques coopérant de manière étanche avec le joint abradable sont réalisées en titane.
• Les aubes rotoriques sont configurées pour fonctionner à une vitesse transsonique.
• L'épaisseur radiale du joint abradable est supérieure ou égale à l'épaisseur moyenne des aubes rotoriques, et/ou supérieure ou égale à 3,00 mm.
• Le feuillard est ferreux, notamment en acier.
• La compacité du joint en matériau abradable est supérieure ou égale à : 90%, ou 95%, ou 98%, ou 99%.

According to advantageous modes of the invention, the compressor can comprise one or more of the following characteristics, taken separately or according to all the possible technical combinations:

• The compressor comprises a composite organic matrix wall on which is disposed the abradable seal, and an interface between the wall and the abradable seal which is formed by a metal strip.
• The rotor blades cooperating sealingly with the abradable seal are made of titanium.
• The rotor vanes are configured to operate at a transonic speed.
• The radial thickness of the abradable seal is greater than or equal to the average thickness of the rotor blades, and / or greater than or equal to 3.00 mm.
• The strip is ferrous, especially steel.
• The compactness of the abradable material seal is greater than or equal to: 90%, or 95%, or 98%, or 99%.

The subject of the invention is also a turbomachine, in particular a turbojet engine, comprising an abradable seal, remarkable in that the composition of the abradable seal is in accordance with the invention, the turbomachine optionally comprising a compressor according to the invention.

The subject of the invention is also a method for producing an abradable gasket of a turbomachine, in particular a turbojet engine, the gasket having an arcuate wall and an abradable composition applied against the arcuate wall, the method comprising the steps of: (a) providing or providing an arcuate wall; (f) thermally spraying an abradable seal composition against the arcuate wall, said composition comprising a majority of aluminum in a metal phase, and a second phase; remarkable in that in step (f) application, the metal phase further comprises nickel, optionally at the beginning and / or at the end of step (f) application the composition is in accordance with the invention.

According to an advantageous embodiment of the invention, during step (f), the composition is applied by plasma spraying.

In general, the advantageous modes of each object of the invention are also applicable to the other objects of the invention. Each object of the invention is combinable with the other objects, and the objects of the invention are also combinable with the embodiments of the description, which in addition are combinable with each other, according to all possible technical combinations, unless otherwise not explicitly mentioned.

Benefits brought

The presence of chromium in the abradable composition provides a better anchoring on a support. For example, the cohesion with the metal strip is improved, especially bonded to a composite organic matrix casing. In parallel, the friable behavior of the abradable resulting from the plasma projection increases. This is in particular due to a better mixture of the metal portion and the second portion. Each of them forms grains of reduced size compared to the state of the art. The geometry and surfaces of the grains may show better interpenetration.

Brief description of the drawings

• The figure 1 represents an axial turbomachine according to the invention.
• The figure 2 is a diagram of a turbomachine compressor according to the invention.
• The figure 3 sketch an abradable gas turbine engine according to the invention.
• The figure 4 illustrates a diagram of a method of producing an abradable turbine engine gasket according to the invention.

Description of the embodiments

In the following description, the terms "internal" and "external" refer to a positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are in reference to the main flow direction of the flow in the turbomachine.

By metallic phase, one can hear the physical property of the material.

By abradable material is meant a material capable of crumbling in contact with a rotorcraft rotor element. This material can be adapted to concentrate wear and deformation while preserving the integrity of the rotor.

The figure 1 represents in simplified manner an axial turbomachine. It is in this case a double-flow turbojet engine. The turbojet engine 2 comprises a first compression level, called a low-pressure compressor 4, a second compression level, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power the turbine 10 transmitted via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. The latter comprise several rows of rotor blades associated with rows of stator vanes. The rotation of the rotor about its axis of rotation 14 thus makes it possible to generate an air flow and to compress it progressively until it reaches the combustion chamber 8.

A commonly designated fan or fan input fan 16 is coupled to the rotor 12 and generates a flow of air which splits into a primary flow 18 passing through the various aforementioned levels of the turbomachine, and into a secondary flow 20 passing through an annular duct. (partially shown) along the machine to then join the primary flow at the turbine outlet.

The secondary flow can be accelerated so as to generate a thrust reaction necessary for the flight of an aircraft. The primary 18 and secondary 20 streams are coaxial annular flows and fitted into one another. They are channeled by the casing of the turbomachine and / or ferrules. For this purpose, the housing has cylindrical walls 21 which can be internal and external.

The figure 2 is a sectional view of a compressor of an axial turbomachine such as that of the figure 1 . The compressor can be a low pressure compressor 4. There can be seen a portion of the blower 16 and the separation nozzle 22 of the primary flow 18 and the secondary flow 20. The rotor 12 comprises several rows of rotor blades 24, in this case three.

The low-pressure compressor 4 comprises a plurality of rectifiers, in this case four, which each contain a row of stator vanes 26. Some stator vanes may be adjustable in orientation, also called variable-pitch vanes. The rectifiers are associated with the fan 16 or a row of rotor blades to straighten the air flow, so as to convert the speed of the flow pressure, including static pressure.

The compressor 4 may comprise an outer casing 28. The latter may comprise an arcuate wall 30. This wall 30 may describe a closed one-piece loop around the axis of rotation 14, or be formed of half-shells, or half -cercles.

The housing 28, and in particular its wall 30 may be made of an organic matrix composite material. The matrix may be reinforced with fibers, possibly in the form of a preform. The reinforcement may comprise fibrous folds, for example carbon fiber or glass fiber.

The stator vanes 26 extend essentially radially from the wall 30, and can be fixed thereto and immobilized by means of pins 32. Optionally, the stator vanes 26 comprise attachment platforms 34, which optionally receive the axes of 32. The blades as the platforms may be titanium.

The stator, via its housing 28, receives at least one annular seal 36, possibly an annular seal 36 around each annular row of rotor blades 24. At least one or more or each annular seal 36 may be an abradable seal with an annular layer of abradable material 38. Thus, the seals are abradable seals 36, they participate in the reduction of leakage by allowing a connection between the vanes 24 and the casing 28. .

Optionally, internal ferrules 40 are connected to the inner ends of the stator vanes 26. These ferrules 40 may also receive an abradable seal as described in the present invention, and cooperating with the rotor 12 sealingly.

The figure 3 represents an abradable gasket 36 of a compressor such as that of the figure 2 . There is shown a wall 34 of casing 28, or support 28, an abradable layer 38 of gasket 36 applied thereto, and a rotor blade end 24 between two stator vanes 26.

The abradable layer 38 extends from one blade platform 26 to the other, which belongs to a neighboring row disposed upstream or downstream. At least one or each abradable seal may be in contact with the material of the blade platforms, possibly in electrical contact.

The abradable layer 38 may be applied directly to the wall 30 of the casing 28. Or again, the seal 36 may comprise an intermediate layer between the support and the abradable layer 38. The intermediate layer may be a strip 42, such as a metal sheet. steel, or nickel sheet. The strip 42 may be perforated and / or cut. It can be of constant thickness. The abradable layer 38 may be thicker than the strip 42.

The strip 42 can be glued to the wall 30, and / or be maintained thanks to the platforms 34 of the blades 26. Optionally, the upstream and / or downstream edges of the strip 42 are clamped between the platforms 34 and the wall 30.

The abradable layer 38 has an inner surface 44 in contact with the primary stream 18. Its surface 44 guides and defines the primary stream 18 during its compression. It can be flush with the internal surfaces of the platforms 34.

The composition of the material forming the abradable layer 38 and therefore the seal 36 may comprise at least two mixed phases, namely a metallic phase and a second phase. The second phase can be mineral and / or organic. The abradable can be composite; and / or granular; and / or with spaces filled by some of its constituents. The second phase can form a lubricant.

The metal phase mainly comprises aluminum. The metal phase of the composition is aluminum-based. That is to say that among the metals of the abradable, the one whose mass is the most important is aluminum. The preponderance of aluminum optimizes the mass of the seal 36. The metallic phase may also comprise chromium, in a lower weight proportion than aluminum.

The metal phase may comprise between 20% and 45% of chromium; and between 55% and 80% aluminum. Aluminum and chromium may be the only two metals in which each of the masses represents at least 0.10%, or at least 1% of the mass of the composition. Optionally, the metal phase may consist of aluminum and chromium.

Optionally, the metal phase may also comprise nickel, especially in lower mass proportion to that of chromium, for example two times lower.

By way of example, the metal phase may comprise, by weight, 10% of chromium and / or 5% of nickel; or else, by weight, 30% of chromium and 10% of nickel.

In addition, the metal phase may optionally include iron, copper, zinc, manganese, magnesium, impurities; these components each representing or in all between 1% and 0.1% of the mass of the metal phase.

The organic material of the second phase of the composition may comprise polymer, such as polyester, polyimide, polyamide-imide, polyether-imide, bismaleimide, fluoroplast, a ketone-based resin, liquid crystal of polymers; or all their possible combinations.

The second phase may also include hexagonal boron nitride, calcium fluoride, molybdenum disulfide, graphite, talc, bentonite, mica; or all their possible combinations. These materials can be considered as mineral materials.

The second phase may comprise a mixture of at least one mineral material with at least one organic material.

The mass of the second phase can represent: from 5% up to 50%, or from 15% up to 25%, optionally 20% of the mass of the composition. The metal phase can represent the majority of the volume of the abradable layer, thus, the metal phase can form there a matrix receiving the second phase.

Optionally, the abradable layer may be formed of grains of metal powders whose inter-grain spaces are filled by the second phase.

The empty space in the abradable layer is less than 1%, preferably less than 0.1%.

The figure 4 represents a diagram of a process for producing an abradable axial turbomachine seal as presented in FIG. figures 2 and / or 3. The seal can be used on a compressor, particularly low-pressure, as detailed in connection with the figures 1 and / or 2.

1. (a)- fourniture ou fabrication 100 d'une paroi arquée, telle celle d'un carter externe de compresseur, ladite paroi matérialisant un support,
2. (b)- fourniture ou fabrication 102 d'aubes statoriques avec des plateformes ;
3. (c)- fourniture ou fabrication 104 d'un feuillard ;
4. (d)- mise en place 106 du feuillard contre le carter, notamment contre la surface interne de la paroi arquée ;
5. (e)- fixation 108 des aubes via leurs plateformes sur la paroi arquée en formant des rangées annulaires ;
6. (f)- application 110 d'une composition d'abradable sur la paroi arquée entre les rangées annulaires de plateformes de sorte à recouvrir le feuillard.

The method comprises the following steps, possibly carried out in the following order:

1. (a) - supply or manufacture 100 of an arcuate wall, such as that of an external compressor casing, said wall materializing a support,
2. (b) - supply or manufacture of stator blades 102 with platforms;
3. (c) - supply or manufacture 104 of a strip;
4. (d) - placing 106 the strip against the housing, in particular against the inner surface of the arcuate wall;
5. (e) - attachment 108 of the vanes via their platforms on the arcuate wall forming annular rows;
6. (f) - application 110 of an abradable composition on the arcuate wall between the annular rows of platforms so as to cover the strip.

At the beginning of step (f) application 110, the composition has a metal phase with mainly aluminum, for example in powder form. The aluminum can be pure, or in the form of an alloy. The same applies to chrome.

The composition may also include chromium and optionally a second metal; both in powders. The chromium mass is at least 20%, or 21%, or 22%, or 23% of the metal phase. The composition of the powder may correspond to the chemical composition of the abradable layer presented above.

At the end of step (f) application 110, at least one or each compound of the composition remains in powder form, or at least one of the compounds has melted, or each compound has melted.

Optionally, some, or at least one, or each type of powder kernel is essentially full. Each grain can form a homogeneous material.

Optionally, one type of grain is hollow, for example aluminum or chromium grains.

During step (f) application 110, the composition can be applied to the casing, thus against the arcuate wall, by plasma spraying. Such a thermal technique is well known to those skilled in the art, it can be carried out in a manner similar to that disclosed in the document EP 1 010 861 A2 . The powder of the second phase can be introduced into the plasma jet downstream of the metal powders. Other techniques are possible. Alternatively, the composition can be applied to the support by sintering, optionally with prolonged heating. In this alternative, some grains may retain their original forms.

The steps: (b) supplying 102 stator vanes; (c) providing or manufacturing a strip; (d) placing the strip against the housing, especially against the inner surface of the arcuate wall; (e) fastening 108 of the blades; are entirely optional according to the invention. Indeed, the abradable composition can be applied to a free blade support and / or strip free. For example, step (f) application 110 can be performed in a groove formed in the thickness of the arcuate wall; and / or directly on the inner surface of the arcuate wall.

The characteristics defined in relation to the composition can be applied to the joint, and vice versa.

Claims (15)

Composition for an abradable gasket (36) for a turbomachine (2), in particular in powder form, said gasket (36) being able to crumble in the event of contact with a rotor (12) of said turbomachine (2), the composition comprising: a metal phase with a mass majority of aluminum, a second phase comprising a mineral material and / or an organic material; characterized in that
the metal phase further comprises chromium and nickel, the metal phase comprising in mass more chromium than nickel. Composition according to Claim 1, characterized in that the metal phase comprises in mass from 20% to 45% of chromium. Composition according to one of Claims 1 to 2, characterized in that the organic material comprises polyester and the mineral material comprises hexagonal boron nitride. Composition according to one of Claims 1 to 3, characterized in that the metal phase represents from 82% to 90% of the mass of the composition. Composition according to one of Claims 1 to 4, characterized in that the second phase represents from 10% to 25% of the mass of the composition. Composition according to one of Claims 1 to 5, characterized in that the second phase comprises at least one of the following materials: polyimide, polyamide-imide, polyether-imide, bismaleimide, fluoroplast, a resin based on ketone, liquid crystal polymers; or all their combinations. Composition according to one of Claims 1 to 6, characterized in that the second phase comprises at least one of the following materials: molybdenum disulphide, graphite, talc, bentonite, mica; or all their combinations. A turbomachine compressor (4; 6), in particular a turbomachine low-pressure compressor (2), comprising a rotor (12) with rotor vanes (24) and an abradable seal (36) sealingly engaging said rotor blades (24), characterized in that the abradable seal (36) comprises a composition according to one of claims 1 to 7. Compressor (4; 6) according to Claim 8, characterized in that the compressor comprises an organic matrix composite wall (30) on which the abradable seal (36) is arranged and an interface between the wall (30) and the seal abradable (36) which is formed by a metal strip (42). Compressor (4; 6) according to one of claims 8 to 9, characterized in that the rotor blades (24) sealingly cooperating with the abradable seal (36) are made of titanium. Compressor (4; 6) according to one of claims 8 to 10, characterized in that the rotor blades (24) are configured to operate at a transonic speed. Compressor (4; 6) according to one of claims 8 to 11, characterized in that the radial thickness of the abradable seal (36) is greater than or equal to the average thickness of the rotor blades (24), and / or higher or equal to 3.00 mm. Turbomachine (2), in particular a turbojet, comprising an abradable seal (36), characterized in that the composition of the abradable seal (36) is in accordance with one of claims 1 to 7, the turbomachine (2) possibly comprising a compressor (4; 6) according to one of claims 8 to 12. Process for producing an abradable gasket (36) for a turbomachine (2), in particular a turbojet engine, the gasket (36) comprising an arcuate wall (30) and an abradable composition applied against the arcuate wall (30), the process comprising the following steps: (a) providing or producing (100) an arcuate wall (30); (f) applying (110) thermal spraying an abradable seal composition (36) against the arcuate wall (30), said composition comprising a majority of aluminum in a metal phase, and a second phase; characterized in that in step (f) applying (110),
the metallic phase further comprises nickel,
optionally at the beginning and / or end of step (f) application (110) the composition is according to one of claims 1 to 7. Process according to claim 14, characterized in that during the step (f) application (110), the composition is applied by plasma spraying.

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