Reinforced attack-board turbomachine blade

Abstract

Turbomachine blade with reinforced leading edge. The invention relates to a turbomachine blade comprising a blade root portion (4) and a blade body portion (5), the blade body portion comprising a core (10) of ceramic matrix composite material covered with an environmental barrier (11), the blade being characterized in that the thickness (e) of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm on the leading edge (3) of the blade. Figure for the abstract: Fig. 3.

Description

Title of the invention: Turbomachine blade with reinforced leading edge Technical field

[0001] The present disclosure relates to an aeronautical turbomachine blade made of ceramic matrix composite material and to a method for manufacturing such a blade. Prior art

[0002] Ceramic matrix composite (CMC) materials withstand temperatures ranging from 600°C to 1400°C.

[0003] Due to their better resistance to high temperatures, CMCs require less cooling. This cooling traditionally comes from a sample in the compressor which impacts the efficiency of the turbomachine, CMC materials therefore make it possible to improve engine efficiency which reduces fuel consumption.

[0004] Furthermore, their use contributes to optimizing the performance of turbo-machines, in particular by reducing the overall mass of the turbo-machine, which further contributes to a reduction in fuel consumption and therefore to a significant reduction in polluting emissions.

[0005] These advantages explain the industrial interest in developing such ceramic matrix composite materials.

[0006] However, CMCs present other challenges before industrial use in an aeronautical turbomachine and in particular in turbomachine blades.

[0007] In particular, compared to the metal alloys they replace, ceramic matrix composite materials are less impact resistant.

[0008] Furthermore, CMC blades have less resistance to the physicochemical environment of a turbomachine compared to metal alloys.

[0009] And finally, blades made of CMC materials are difficult to machine.

[0010] It should nevertheless be noted that there are solutions to each of the problems taken independently.

[0011] For example, it has been proposed to add a metal foil to a leading edge of a composite material blade to protect the latter from a possible impact.

[0012] Similarly, it has been proposed to coat CMC blades with an environmental barrier chemically protecting the blade against corrosion and / or very high temperatures.

[0013] Finally, methods of manufacturing CMC blades called “near net” are proposed. shape", that is to say having at the end of their preparation a shape as close as possible to that desired for their use. The need for machining of these blades is then strictly reduced to a minimum, which makes the manufacturing process much faster.

[0014] It nevertheless remains complicated and costly to overcome the three problems set out above using specific methods for each of said problems. Statement of the invention

[0015] The present invention specifically aims at a blade made of ceramic matrix composite material which would make it possible to solve the three problems mentioned above in a single way.

[0016] For this purpose, it relates, according to a first of its aspects, to a turbomachine blade comprising a blade root portion and a blade body portion, the blade body portion comprising a core made of ceramic matrix composite material covered with an environmental barrier, the blade being characterized in that the thickness of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm on the leading edge of the blade.

[0017] It will be appreciated that in the application, the "thickness" of a layer is understood in its usual sense, the smallest extension dimension. Generally, this dimension is obtained in the direction perpendicular to the surface of the composite material core.

[0018] In one aspect of the invention, the environmental barrier layer provides excellent protection of the underlying CMC against oxidation and corrosion, similar to the environmental barriers of the prior art.

[0019] Furthermore, the environmental barrier thickness provides excellent protection of the leading edge of the blade against impacts from foreign bodies. Indeed, the inventors have found that for an environmental barrier thickness greater than or equal to 1.0 mm, the latter ensures that in the event of an impact, only the environmental barrier is damaged, and that it also allows all of the impact energy to be dissipated in the environmental barrier layer. The brittle behavior of the environmental barrier is thus used to dissipate all of the impact energy, which ensures that the environmental barrier layer protects the underlying substrate and that the ceramic matrix composite material portion of the blade is not damaged by the impact.

[0020] Furthermore, if an environmental barrier layer becomes damaged in the event of an impact, it is relatively simple to deposit, particularly for such environmental barrier thicknesses. It is also much less expensive to deposit a new environmental barrier on the surface of a blade than to repair or replace the composite material core of such a blade.

[0021] It is thus possible to manufacture blades that are much less expensive than those of the prior art, which also do not need to be replaced if they suffer an impact.

[0022] The causes of such an impact for a turbomachine in operation may be, for example, the ingestion of a bird by said turbomachine.

[0023] In a blade of the invention, the ceramic matrix composite material forms the core of the blade, that is to say it ensures the mechanical properties and excellent adhesion of the environmental barrier, but it does not play an aerodynamic role.

[0024] In a blade according to the invention, it is in fact the environmental barrier which ensures the aerodynamic role of the blade.

[0025] This results in greatly simplified blade production because the machining to obtain the desired aerodynamic profile is carried out in the environmental barrier, and not in the CMC material.

[0026] In particular, all the efforts usually necessary to obtain a surface condition of the CMC material sufficiently smooth for the aerodynamic needs of a turbomachine blade can be saved here because the CMC material is only present as the core of the blade and it is the environmental barrier, for which machining is simpler, to meet this need.

[0027] Machining the environmental barrier is much simpler than that of a ceramic matrix composite material because it is much less hard than a CMC material.

[0028] Thus, the invention makes it possible to protect the leading edge of a composite material blade against impacts with a simpler solution than those proposed in the prior art which required attaching a metal foil to a composite material blade.

[0029] In one embodiment, the turbomachine blade according to the invention comprises a blade root portion and a blade body portion, the blade body portion comprising a core made of ceramic matrix composite material covered with an environmental barrier, the blade being characterized in that the thickness of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm on the leading edge of the blade, in that the thickness of the environmental barrier decreases continuously between the leading edge and the trailing edge and in that the thickness of the environmental barrier is less than or equal to 40 μm for the trailing edge.

[0030] The expression "decreases continuously" must be understood in its mathematical sense. The function which represents the thickness of the environmental barrier as a function of the distance from the leading edge is continuous and is decreasing.

[0031] In one embodiment, the thickness of the environmental barrier may decrease strictly and continuously between the leading edge and the trailing edge.

[0032] An advantage of such a blade is that the trailing edge of the blade remains as thin as those of the blades of the prior art, because the thickness of the environmental barrier is very low, which is very advantageous for aerodynamic reasons.

[0033] Such a blade thus combines excellent protection of the blade core thanks to the very significant thickness of the environmental barrier covering the leading edge and also has excellent aerodynamic characteristics since the environmental barrier is very thin for the trailing edge.

[0034] In one embodiment, the thickness of the environmental barrier for the trailing edge may be between 20 μm and 40 μm.

[0035] In one embodiment, the thickness of the environmental barrier in the blade root portion is less than or equal to 100 μm.

[0036] Indeed, since the blade root portion is not subject to impacts nor does it require special machining for aerodynamic reasons, it is not necessary for the environmental barrier to be thicker than for blades of the prior art.

[0037] In one embodiment, the environmental barrier comprises silicon, for example comprises a rare earth silicate or mullite. For example, the environmental barrier may comprise yttrium disilicate Y2Si2O7, ytterbium disilicate Yb2Si2O7, mullite (3Al2O3.2SiO2) or a mixture of two or more of these compounds.

[0038] In one embodiment, the blade further comprises a bonding layer disposed between the ceramic matrix composite material core and the environmental barrier.

[0039] In one embodiment, the bonding layer may comprise silicon and / or silica SiO2, or even consist of silica SiO2.

[0040] Such an adhesion layer ensures excellent chemical continuity between the thermal barrier and the CMC material. In addition, such an adhesion layer provides excellent compatibility in terms of thermal expansion between the CMC material and the thermal barrier, which reduces the risk of delamination of the environmental barrier during operation.

[0041] In one embodiment, the blade is selected from a fixed blade, for example a blade of a high pressure distributor or a blade of a low pressure distributor, or a moving blade, for example a high pressure turbine blade or a low pressure turbine blade.

[0042] In one embodiment, the blade is a moving blade. Indeed, it is for the latter that the risk of fracture in the event of impact is the most marked and it is therefore for the latter that it is particularly desirable to obtain the advantages described above.

[0043] In one embodiment, the blade comprises a connecting portion in lower between the blade root part and the blade body part in which the thickness of the environmental barrier is strictly increasing.

[0044] This connection portion ensures excellent mechanical continuity between the ceramic matrix composite material parts of the blade body part and the blade root part.

[0045] In particular, this avoids having sudden variations in the thickness of the composite material parts, which avoids areas of stress accumulation, and therefore reduces the fragility of the blade as a whole.

[0046] Preferably, such a connecting portion has an extension dimension less than or equal to 10 mm in the longitudinal direction of the blade, for example between 3.0 mm and 10 mm.

[0047] Limiting the longitudinal dimension of the lower connecting portion, where the environmental barrier thickness is less than that of the blade body, ensures that the aforementioned advantages obtained precisely through the thickness of the environmental barrier are retained, while avoiding stress accumulation zones.

[0048] The longitudinal direction of the blade is understood to be the direction of greatest extension of the blade, and generally the direction which extends from the blade root towards the blade body part.

[0049] In an embodiment where the blade is a fixed blade, the blade may then further comprise a blade tip portion having an environmental barrier thickness less than or equal to 100 μm.

[0050] Indeed, for the same reasons as those described for the blade root part, it is not necessary for the environmental barrier thickness to be thicker than for conventional blades.

[0051] In an embodiment where the blade is a fixed blade, the blade may comprise a blade tip portion and further comprise an upper connecting portion between the blade tip portion and the blade body portion in which the thickness of the environmental barrier is strictly increasing.

[0052] This upper connection portion makes it possible to obtain at the blade head the same advantages as those described above for the lower connection portion.

[0053] Preferably, such an upper connecting portion has an extension dimension less than or equal to 10 mm in the vertical direction of the blade, for example between 3.0 mm and 10 mm.

[0054] Limiting the longitudinal dimension of the upper connecting portion makes it possible to obtain the same advantages at the blade head as those described above for the lower connecting portion.

[0055] In one embodiment, the ceramic matrix composite material is a SiC / SiC material.

[0056] According to another of its aspects, the invention relates to a method of manufacturing a blade as described above, the method comprising a step of depositing an environmental barrier layer on a core made of ceramic matrix composite material, followed by a step of machining the environmental barrier layer.

[0057] In one embodiment, the method comprises, before the step of depositing an environmental barrier layer, a step of depositing a bonding layer on the core made of ceramic matrix composite material.

[0058] In one embodiment, the bonding layer comprises silicon and / or silica SiO2, and the step of depositing the bonding layer can be carried out by physical vapor deposition (PVD), chemical vapor deposition (CVD) by vacuum plasma spraying (VPS), or by atmospheric plasma spraying (APS).

[0059] In one embodiment, the deposition of the environmental barrier can be carried out by thermal spraying, for example by plasma spraying.

[0060] It will be noted that these methods differ from the liquid depositions usually envisaged in the prior art for the deposition of an environmental barrier.

[0061] Indeed, these liquid methods are not suitable for depositing thicknesses consistent with those of a described blade.

[0062] This is why it is preferred to deposit the environmental barrier by plasma projection which is compatible with the thicknesses involved.

[0063] Thermal spray deposition techniques are certainly less precise than those of the prior art, but allow significant thicknesses of environmental barrier to be deposited, and the environmental barrier can be machined. The subsequent machining step makes it possible to correct any inaccuracies in the deposition step, and this is why these less expensive deposition techniques, which allow greater thicknesses of the environmental barrier layer to be deposited, can be chosen.

[0064] In one embodiment, the machining step may be performed by single-layer or multi-layer grinding.

[0065] According to another of its aspects, the invention relates to a turbomachine comprising a blade as described above.

[0066] According to another of its aspects, the invention relates to an aircraft comprising a turbomachine as described above. Brief description of the drawings

[0067] [Fig.l] [Fig.l] is a schematic representation of a turbomachine.

[0068] [Fig.2] [Fig.2] is a schematic representation of a prior art blade.

[0069] [Fig.3] [Fig.3] schematically represents a blade in one embodiment of the invention.

[0070] [Fig.4] [Fig.4] schematically represents a connection portion in one embodiment of the invention.

[0071] [Fig.5] [Fig.5] schematically represents a stack for obtaining a blade according to the invention. Description of the embodiments

[0072] The invention is now described by means of figures, present for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0073] [Fig. 1] represents, in section along a vertical plane passing through its main axis A, a double-flow turbojet 21. It comprises from upstream to downstream according to the circulation of the air flow, a fan 22, a low-pressure compressor 23, a high-pressure compressor 24, a combustion chamber 25, a high-pressure turbine 26, and a low-pressure turbine 27.

[0074] In a known manner, the low pressure compressor 23, the high pressure compressor 24, the high pressure turbine 26, and the low pressure turbine 27 comprise fixed blades and mobile blades, one or more of which may be as described above.

[0075] [Fig.2] illustrates a blade 1 made of ceramic matrix composite material according to the prior art.

[0076] Such a blade 1 comprises a blade body portion 5 and a blade root portion 4.

[0077] This blade comprises a leading edge 3 and a trailing edge 7. As shown, the leading edge 3 is reinforced by a metal foil 8 arranged on the latter.

[0078] The metal foil 8 provides mechanical protection for the leading edge of the blade. In the event of an object being ingested by the engine, it is the metal foil that will come into contact with said object and not the body of the blade 5.

[0079] Thus, the blade 1 is protected by the foil 8. However, such blades have disadvantages, notably linked to the arrangement of the foil 8 on the blade 1.

[0080] In particular, the difference in thermal expansion coefficients between the blade 1 and the foil 8 makes it difficult to hold the foil 8 on the blade 5.

[0081] A blade according to the invention provides an alternative way of protecting the leading edge, which also ensures protection of the CMC material against the corrosive and oxidizing environment of the turbomachine.

[0082] [Fig.2] further illustrates the transverse direction T and longitudinal L of a blade.

[0083] Furthermore, [Fig.2] illustrates in dotted lines III the section of the view of [Fig.3], and in dotted lines IV, the position of the view of [Fig.4].

[0084] However, it should be noted that these indications are only for reference purposes, since figures 3 and 4 relate to blades according to the invention, while [Fig.2] is a blade of the prior art outside the invention.

[0085] [Fig.3] illustrates a particular section of a blade according to the invention.

[0086] As described above, the blade of [Fig. 3] comprises a ceramic matrix composite material core 10 and an environmental barrier 11.

[0087] [Fig.3] further illustrates what is meant by the thickness of the environmental barrier.

[0088] For this, the thickness eb e2, e3, e4 is indicated at several points more or less close to the leading edge 3, being the closest to the leading edge 3 and e4 the most distant.

[0089] In the embodiment shown in [Fig. 3], the thickness of the environmental barrier 11 in a blade of the invention decreases between the leading edge 3 and the trailing edge 4.

[0090] As indicated above, the thickness ei of the environmental barrier 11 at the leading edge 3 is greater than or equal to 1.0 mm.

[0091] Finally, [Fig.3] illustrates that the variation in thickness is continuous. This ensures excellent aerodynamic properties for the entire blade.

[0092] Furthermore, it should be understood that the variation in thickness is assessed independently on the intrados and on the extrados. Indeed, and as is also shown in [Fig. 3], the thickness of the environmental barrier 11 may be different for the intrados and the extrados.

[0093] However, whether we look at the thickness of the environmental barrier 11 on the intrados or that on the extrados, this thickness decreases between the leading edge 3 and the trailing edge 4.

[0094] In an embodiment not shown, the environmental barrier thickness may be constant and greater than or equal to 1.0 mm across the entire blade body portion.

[0095] [Fig.4] illustrates what is meant by connection portion 6. Such a connection portion is located between the blade root zone 4 and the blade body zone 5.

[0096] As shown in [Fig.4], the connecting portion 6 comprises a thickness e of environmental barrier 11 which progressively increases in the connecting portion 6.

[0097] [Fig.4] further illustrates what is meant by the HR extension of the portion of rac- rope 6 in the longitudinal direction.

[0098] In one embodiment, the extension HR of the connecting portion 6 is less than or equal to 10 mm, for example between 3.0 mm and 10 mm.

[0099] The connecting portion ensures excellent compatibility between the CMC portions of the blade body 5 and the blade root portion 4, while allowing the desired thickness to be achieved quickly.

[0100] [Fig.5] finally illustrates a stack of a core made of ceramic matrix composite material 10, a bonding layer 110 and an environmental barrier 11.

[0101] In one embodiment it is possible to arrange a bonding layer 110 between the substrate 10 and the environmental barrier 11.

[0102] This embodiment allows the stack to have better resistance to delamination, in particular by improving continuity in terms of thermal expansion coefficients.

[0103] Furthermore, the bonding layer 110 can play a role in protecting the substrate 10 made of composite material against corrosion.

[0104] In one embodiment, the blade does not comprise any layers other than the ceramic matrix composite material core 10, the adhesion layer 110 and the environmental barrier 11.

[0105] In other words, the bonding layer 110 is arranged directly in contact with the core of ceramic matrix composite material 10, and the environmental barrier layer 11 is arranged directly in contact with the bonding layer 110.

Claims

Claims

1. A turbomachine blade comprising a blade root portion (4) and a blade body portion (5), the blade body portion comprising a core (10) of ceramic matrix composite material covered with an environmental barrier (11), the blade being characterized in that the thickness (e) of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm on the leading edge (3) of the blade.

2. A turbomachine blade according to claim 1, wherein the thickness of the environmental barrier decreases continuously between the leading edge and the trailing edge and wherein the environmental barrier thickness is less than or equal to 40 μm for the trailing edge (8).

3. A turbomachine blade according to claim 1 or 2, wherein the thickness of the environmental barrier (11) in the blade root portion (4) is less than or equal to 100 μm.

4. A turbomachine blade according to any one of claims 1 to 3, wherein the environmental barrier (11) comprises yttrium disilicate Y2Si2O7, ytterbium disilicate Yb2Si2O7, mullite, (3Al2O3.2SiO2) or a mixture of two or more of these compounds.

5. Turbomachine blade according to one of claims 1 to 4, in which a bonding layer (110) is arranged between the core (10) made of ceramic matrix composite material and the environmental barrier (H).

6. Turbomachine blade according to claim 5, in which the adhesion layer (110) comprises silicon and / or silica SiO2.

7. Turbomachine blade according to one of claims 1 to 6, which is chosen from a blade of a high pressure distributor, a blade of a low pressure distributor, a high pressure turbine blade or a low pressure turbine blade.

8. Turbomachine blade according to one of claims 1 to 7, further comprising a lower connecting portion (6) between the blade root part (4) and the blade body part (5) in which the thickness (e) of the environmental barrier (11) is strictly increasing.

9. Method of manufacturing a blade according to one of claims 1 to 8 comprising a step of depositing an environmental barrier layer (11) on a core made of ceramic matrix composite material. (10), followed by a step of machining the environmental barrier layer.

10. Manufacturing method according to claim 9, wherein the step of depositing the environmental barrier (11) is carried out by plasma spraying.

11. Manufacturing method according to claim 9 or 10, which comprises, before the step of depositing an environmental barrier layer (11), a step of depositing a bonding layer (110) on the core of ceramic matrix composite material (10).

12. Aeronautical turbomachine comprising a blade according to one of claims 1 to 8.

13. Aircraft comprising an aeronautical turbomachine according to claim 12.

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