Reinforced attack-side 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 a method for manufacturing such a blade. Prior art

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

[0003] Due to their superior resistance to high temperatures, CMCs require less cooling. Since this cooling is traditionally obtained from a source in the compressor, which impacts the turbomachine's efficiency, CMC materials therefore improve engine efficiency, thereby reducing fuel consumption.

[0004] Furthermore, their use helps to optimize the performance of turbomachines, in particular by reducing the overall mass of the turbomachine, which further contributes to a decrease in fuel consumption and therefore to a significant reduction in pollutant 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 metallic alloys they replace, ceramic matrix composite materials are less impact resistant.

[0008] In addition, CMC blades have less resistance to the physico-chemical environment of a turbomachine compared to metallic alloys.

[0009] And finally, the 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 attach a metallic shim to a leading edge of a blade made of composite material 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 for manufacturing CMC blades known as "near net" are proposed. "Shape," meaning that after preparation, they have a shape as close as possible to the desired shape for their intended use. The machining requirements for these blades are then strictly reduced to a minimum, which significantly speeds up the manufacturing process.

[0014] It remains complicated and costly to overcome the three problems outlined above using specific methods for each of said problems. Description of the invention

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

[0016] For this purpose, it relates according to a first of its aspects to a turbomachine blade comprising a blade root part and a blade body part, the blade body part comprising a core 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 part is greater than or equal to 1.0 mm on the leading edge of the blade.

[0017] It will be appreciated if, in the application, the "thickness" of a layer is understood in its usual sense, as the smallest extensional 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 environmental barriers of the prior art.

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

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

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

[0022] The causes of such an impact on a turbomachine in operation may be, for example, the ingestion of a volatile 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 grip of the environmental barrier, but it does not play an aerodynamic role.

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

[0025] This results in a greatly simplified production of the blade 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 required to obtain a surface finish of the CMC material sufficiently smooth for the aerodynamic requirements of a turbomachine blade can be saved here because the CMC material is present only as the core of the blade and it is at the environmental barrier, for which machining is simpler to meet this need.

[0027] Machining the environmental barrier is much simpler than machining 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 metallic shim 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 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 pm for the trailing edge.

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

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

[0032] One advantage of such a blade is that the trailing edge of the blade remains as thin as those of prior art blades, 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 large thickness of the environmental barrier covering the leading edge and also presents 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 can be between 20 pm and 40 pm.

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

[0036] Indeed, since the blade foot part 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 prior art blades.

[0037] In one embodiment, the environmental barrier comprises silicon, for example, 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 be made of silica SiO2.

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

[0041] In one embodiment, the blade is chosen 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 movable blade. Indeed, it is for these blades that the risk of fracture in the event of an impact is most pronounced, and it is therefore for these blades 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 foot part and the blade body part in which the thickness of the environmental barrier is strictly increasing.

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

[0045] In particular, this avoids 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 thickness of the environmental barrier is less than that of the blade body, ensures the preservation of the aforementioned advantages obtained precisely thanks to the thickness of the environmental barrier, while avoiding areas of stress accumulation.

[0048] The longitudinal direction of the blade is understood as the greatest extensional direction of the blade, and generally the direction extending from the blade foot towards the blade body part.

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

[0050] Indeed, for the same reasons as those described for the blade foot 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 include a portion of blade head and further include an upper connecting portion between the part of blade head and the part of blade body in which the thickness of the environmental barrier is strictly increasing.

[0052] This upper connecting portion allows the same advantages to be obtained at the blade head as those described above for the lower connecting 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 at the blade head the same advantages 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 aspect of it, the invention relates to a method for manufacturing a blade as described above, the method comprising a step of depositing an environmental barrier layer on a ceramic matrix composite material core, followed by a step of machining the environmental barrier layer.

[0057] In one embodiment, the process includes, before the step of depositing an environmental barrier layer, a step of depositing an adhesion layer on the core of ceramic matrix composite material.

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

[0059] In one embodiment, the environmental barrier can be deposited by thermal projection, for example by plasma projection.

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

[0061] Indeed, these liquid-based methods are not suitable for depositing thicknesses conforming to those of a described blade.

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

[0063] While thermal spray deposition techniques are less precise than those of the prior art, they allow for the deposition of significant thicknesses of environmental barrier, and the environmental barrier can be machined. The subsequent machining step allows for the correction of any inaccuracies from the deposition step, and this is why these less expensive deposition techniques, which allow for the deposition of greater thicknesses of the environmental barrier layer, can be chosen.

[0064] In one embodiment, the machining step can be carried out by single-layer or multi-layer grinding.

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

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

[0067] [Fig.1] Fig.1 is a schematic representation of a turbomachine.

[0068] [Fig.2] The [Fig.2] is a schematic representation of a dawn from the earlier art.

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

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

[0071] [Fig.5] Fig.5 schematically represents a stacking for obtaining a blade according to the invention. Description of the implementation methods

[0072] The invention is now described by means of figures, which are provided 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 cross-section along a vertical plane passing through its main axis A, a turbofan engine 21. It comprises, from upstream to downstream along the airflow circulation, 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 moving 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 part 5 and a blade foot part 4.

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

[0078] The metal shim 8 provides mechanical protection to the leading edge of the blade. In the event of an object being ingested by the engine, it is the metal shim 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 shim 8. However, such blades have disadvantages, particularly related to the arrangement of the shim 8 on the blade 1.

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

[0081] A blade according to the invention offers 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 direction L of a blade.

[0083] In addition, [Fig. 2] illustrates in dotted lines III the cross-section of the view of [Fig. 3], and in dotted line 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 prior art blade outside the invention.

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

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

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

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

[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 that the entire blade has excellent aerodynamic properties.

[0092] Furthermore, it must be understood that the variation in thickness is assessed independently on the intrados and extrados. Indeed, and as is also shown in [Fig. 3], the thickness of the environmental barrier 11 can be different for the intrados and 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 illustrated, the environmental barrier thickness can be constant and greater than or equal to 1.0 mm over the entire blade body portion.

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

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

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

[0098] In one embodiment, the HR extension 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 foot portion 4, while allowing the desired thickness to be achieved quickly.

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

[0101] In one embodiment it is possible to place an adhesion layer 110 between the substrate 10 and the environmental barrier 11.

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

[0103] In addition, 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 include any layers other than the ceramic matrix composite material core 10, the tack layer 110 and the environmental barrier 11.

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

Claims

Demands

1. 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. 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 thickness of the environmental barrier is less than or equal to 40 pm for the trailing edge (8).

3. Turbomachine blade according to claim 1 or 2, wherein the thickness of the environmental barrier (11) in the blade foot portion (4) is less than or equal to 100 pm.

4. 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 any one of claims 1 to 4, wherein a tack layer (110) is disposed between the core (10) of ceramic matrix composite material and the environmental barrier (H).

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

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

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

9. A method for manufacturing a blade according to any one of claims 1 to 8 comprising a step of depositing an environmental barrier layer (11) onto a ceramic matrix composite core (10), followed by a machining step of the environmental barrier layer.

10. A manufacturing method according to claim 9, wherein the environmental barrier deposition step (11) is carried out by plasma projection.

11. A manufacturing method according to claim 9 or 10, which includes, prior to the step of depositing an environmental barrier layer (11), a step of depositing an adhesion layer (110) on the core of ceramic matrix composite material (10).

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

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

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