Turbomachine blade, turbomachine and method for manufacturing the blade

Abstract

The invention relates to a turbomachine blade (1) comprising: an external enclosure (10) comprising a pressure-side wall (11) and a suction-side wall (12) delimiting an interior volume therebetween; an insert (30) arranged in the interior volume so as to form an air passage (40) between the insert (30) and the external enclosure (10); and at least one breakable joining part (20) connected to the insert (30) on one side and to the external enclosure (10) on the other side; wherein at least one of the mechanical breaking strength of the breakable joining part (20), the mechanical breaking strength between the breakable joining part (20) and the external enclosure (10) and the mechanical breaking strength between the breakable joining part (20) and the insert (30) is lower than the mechanical breaking strength of the external enclosure (10) and the mechanical breaking strength of the insert (30).

Description

Description Title of the invention: Turbomachine blade, turbomachine and method for manufacturing the blade Technical Field

[0001] This presentation concerns turbomachine blades, in particular high-pressure turbomachine distributor blades. Previous technique

[0002] We know of high-pressure turbomachine distributor blades, which guide the flow of hot gas from the combustion chamber to drive turbines and are equipped with cooling circuits to preserve the integrity of the blades even when subjected to extreme operating temperatures.

[0003] Hollow blades are used, into which inserts are fitted to achieve better distribution of cooling gas flow within the blade and thus better blade cooling. The inserts can be fixed at the top or bottom of the blade, the insert and the blade then being independent over most of the blade's height.

[0004] To optimize geometry and reduce costs, it would be advantageous to manufacture the blade and insert together. However, the lack of material continuity between the insert and an external portion of the blade can lead to deformations resulting in cracks within the blade, or even failure to meet manufacturing tolerances, thus impairing the flow of cooling gases. These problems associated with blade manufacturing are even more pronounced when using additive manufacturing methods.

[0005] However, ensuring material continuity between the insert and an external part of the blade can lead to stress transmission between parts subjected to extreme thermomechanical stresses. operation of the turbomachine, which can thus cause a rupture within the blade, the insert and an outer part of the blade. Description of the invention

[0006] The present presentation aims to propose a turbomachine blade whose manufacture is facilitated without degrading its performance in turbomachine operation.

[0007] For this purpose, the present exposition concerns a turbomachine blade comprising: an outer casing including an intrados wall and an extrados wall delimiting between them an inner volume, an insert disposed in the inner volume so as to form an air passage between the insert and the outer casing; and at least one breakable connecting part, connected on one side to the insert and on the other side to the outer casing; in which at least one of the mechanical resistance to break of the breakable connecting part, the mechanical resistance to break between the breakable connecting part and the outer casing and the mechanical resistance to break between the breakable connecting part and the insert is less than the mechanical resistance to break of the outer casing and the mechanical resistance to break of the insert.

[0008] The upper and lower surfaces of the wing can meet at a leading edge on one side and a trailing edge on the other. The cross-section of the outer shell can be closed, for example, when viewed in a cross-sectional plane transverse to the general direction in which the blade extends. The cross-section of the outer shell can be substantially closed, for example, closed except for localized cooling vents allowing, for example, air film cooling.

[0009] An air passage is defined as a continuous volume between an inlet and an outlet distinct from the inlet, allowing the passage of air or any other fluid between the inlet and the outlet.

[0010] A break between two parts is understood to mean a complete or partial break in the connection between the two parts. A break between two parts of a part is understood to mean a complete or partial break between said two parts.

[0011] Mechanical resistance to breakage is understood to mean the mechanical resistance to breakage in response to thermal or mechanical stresses, for example a simple or compound force, repeated or not, in particular in tension, compression, shear, and / or bending, or any other mode of loading known to a person skilled in the art.

[0012] In the case of a stress involving the breakable joint portion, the breaking strength of the outer casing is understood to be the breaking strength of a region of the outer casing also subjected to said stress, generally around an interface between the breakable joint portion and the outer casing. Similarly, in the case of a stress involving the breakable joint portion, the breaking strength of the insert is understood to be the breaking strength of a region of the insert also subjected to said stress, generally around an interface between the breakable joint portion and the insert.

[0013] In other words, at least one of the following mechanical resistances to breakage: the mechanical resistance to breakage of the breakable joint portion, the mechanical resistance to breakage between the breakable joint portion and the outer casing, and the mechanical resistance to breakage between the breakable joint portion and the insert, is less than the mechanical resistance to breakage of the outer casing and the mechanical resistance to breakage of the insert if, - the mechanical resistance to breakage of the breakable joint portion is less than the breaking strength of the outer casing and the breaking strength of the insert; and / or - the mechanical resistance to breakage between the breakable junction part and the outer casing is less than the mechanical resistance to breakage of the outer casing and the resistance to breakage of the insert; and / or - the mechanical resistance to breakage between the breakable junction part and the insert is less than the mechanical resistance to breakage of the outer casing and the resistance to breakage of the insert.

[0014] In other words, following the onset of stress in the assembly formed by the breakable joint section, the outer casing, and the insert, any potential failure is localized within the breakable joint section, in the sense that the failure separates the breakable joint section into two pieces, and / or at at least one of the interfaces between the breakable joint section and the insert or outer casing, in the sense that the failure separates the breakable joint section from the insert and / or the outer casing. Specifically, following the onset of stress in the assembly formed by the breakable joint section, the outer casing, and the insert, the failure does not occur within the insert or the outer casing before the breakable joint section itself or one of its interfaces with the insert or the outer casing breaks.

[0015] For the sake of brevity but without loss of generality, we will henceforth use the term "break" to refer indifferently to the break of the breakable part of the junction itself and / or the break between the breakable part of the junction and the outer envelope and / or the break between the breakable part of the junction and the insert, unless a particular mention or the context gives the term "break" a different meaning.

[0016] Before breaking, the breakable junction section supports the insert within the outer casing, ensuring geometric continuity between the outer casing and the insert, which improves the blade's manufacturability. Such a blade is particularly well-suited for manufacturing using an additive manufacturing process.

[0017] Geometric continuity refers to the continuity of material within a part or set of parts, regardless of the shape of the part or set of parts. In this case, it is possible to move continuously from the outer casing to the insert via the breakable joining section, whether or not these parts are extensions of each other in terms of shape, material, etc.

[0018] In the event of mechanical or thermomechanical stress leading to breakage, the breakage is localized and / or confined to the breakable section of the joint or to one of its interfaces with the insert and the outer casing. This confinement of the breakage to the breakable section of the joint thus prevents damage to the blade, particularly to the insert and the outer casing.

[0019] Once the blade is manufactured, the complete break also makes it possible to make the insert geometrically independent of the outer shell while keeping the outer shell away from the insert, in particular at a distance associated with good blade cooling efficiency.

[0020] The failure may be preceded, accompanied, or replaced by one or more other types of damage, such as plastic deformation. The mechanical resistance associated with this other damage may be considered alternatively to, or in addition to, the mechanical resistance to failure. For example, in the case of damage in the form of plastic deformation, the deformation is localized and / or confined to the breakable portion of the joint or to one of its interfaces with the insert and the outer casing, thus preventing damage to the blade, particularly to the insert and the outer casing.

[0021] Once the blade is manufactured, damage, for example total or partial breakage or plastic deformation, can further lead to a redistribution of stresses within the part, making it possible to further prevent unwanted damage to the blade.

[0022] During turbomachine operation, the temperature of the outer casing is higher than the temperature of the insert, causing the outer casing (located in a "hot" zone) and the insert (located in a "cold" zone) to expand differently. This differential expansion can lead to rupture at the breakable junction. After rupture, the geometric independence of the outer casing and the insert ensures independent thermo-mechanical displacements between the hot and cold zones, thus preventing the risk of rupture within the outer casing or the insert associated with different displacements between hot and cold zones.

[0023] Improved manufacturability and the containment of the rupture at the breakable junction section ensure the integrity of the outer casing and the insert during turbomachine operation, enabling cooling of the turbine blade, for example, through forced internal convection or impact jet cooling. Furthermore, by increasing manufacturing flexibility, the presence of a breakable junction section allows for more sophisticated and efficient blade designs, particularly in terms of cooling. Such a blade is therefore compatible with high-temperature turbomachine operation and high thermal performance.

[0024] In some embodiments, the blade is a high-pressure turbomachine distributor blade.

[0025] The high-pressure distributor receives high-temperature combustion gases from the combustion chamber. By improving the cooling capabilities of the high-pressure distributor blades, the turbomachine can operate at high temperatures while maintaining high thermal performance.

[0026] However, it is understood that the blade can be located in other positions within the turbomachine. For example, the blade could be a blade from another valve, such as a low-pressure valve.

[0027] In some embodiments, the breakable joint portion has a length between 0.2 mm and 2 mm, preferably between 0.5 mm and 1 mm.

[0028] The length of the breakable joint section is measured along a straight line spacing between the insert and the outer casing. The length of the breakable joint section thus corresponds to the length between the respective interfaces of the breakable joint section with the outer casing and the insert, i.e., also to the smallest distance separating said interfaces.

[0029] The length of the breakable junction section is one of the parameters determining proper impact jet cooling of the outer casing from the insert. The cross-section of the air passage, which determines the airflow velocity through the air passage, depends on the length of the breakable junction section and the width of the air passage, the width being measured perpendicular to the length direction of the breakable section and to the general direction in which the blade extends.

[0030] Such values ​​for the breakable junction section length ensure good cooling efficiency of the blade, particularly the outer casing.

[0031] In some embodiments, the breakable joint portion has a minimum thickness of less than 0.5 mm, preferably less than 0.3 mm. The minimum thickness is the smallest local thickness of the breakable joint portion. For the purposes of this description, the minimum thickness may also be located at the interface between the breakable joint portion and at least one of the outer casing and the insert.

[0032] The thickness of the breakable junction part is measured along a direction transverse to the neutral fiber of the breakable junction part.

[0033] Such dimensions of the breakable junction portion ensure the support function of the insert and the outer casing relative to each other, while concentrating the stresses at the narrowing associated with the minimum thickness, which allows the break to be located in the breakable junction portion, particularly at the narrowing.

[0034] In some embodiments, the thickness is minimal at a position where the cross-section is minimal.

[0035] The cross-sectional area is measured in a plane perpendicular to the neutral axis of the breakable junction portion. The minimum cross-sectional area is the smallest cross-sectional area locally occupied by the breakable junction portion. For the purposes of this document, the minimum cross-sectional area may also be located at the interface between the breakable junction portion and at least one of the outer casing and the insert.

[0036] Such dimensions of the breakable junction part make it possible to ensure the support function of the insert and the outer envelope, while ensuring a concentration of stresses at the narrowing associated with the minimum cross section allowing the rupture to be located in the breakable junction part, in particular at the narrowing.

[0037] In some embodiments, the breakable joint portion comprises a first part and a second part connected to each other at an angle of less than 90°, preferably less than 45°. Such an angle easily concentrates stresses and provides a preferred direction of failure.

[0038] In some embodiments, at least one of the insert and the outer casing is locally reinforced at the point of its connection with the breakable junction part.

[0039] Local reinforcement at the level of a connection with the breakable part of the junction means reinforcement at least in an area stressed when a stress is applied to the breakable part of the junction.

[0040] Local reinforcement can be achieved in various ways, for example by adding thickness, mechanical treatment or chemical treatment.

[0041] This reinforcement further helps to locate the break at the breakable part of the junction and to limit the transmission of this break, and thus to preserve the integrity of the outer casing and / or the insert.

[0042] The invention also relates to a blade comprising a plurality of breakable junction parts arranged along an airflow direction within the air passage.

[0043] The plurality of breakable joining parts allows for better support of the insert and the outer casing relative to each other, along the direction of airflow.

[0044] In some embodiments, the distance between two successive breakable joining parts along the direction of airflow is between 0.2 mm and 3 mm, preferably between 0.4 mm and 1 mm.

[0045] This distance ensures the support function of the breakable joint section while respecting manufacturability constraints. For example, in the case of blade manufacturing using a method that includes a powder bed additive manufacturing step, this distance allows for the depowdering of the blade.

[0046] The invention also relates to a turbomachine comprising a blade according to the present invention.

[0047] The invention also relates to a method for manufacturing a turbomachine blade according to the present invention, comprising at least one powder bed additive manufacturing step.

[0048] In some embodiments, the turbomachine blade according to the present invention is manufactured as a single piece. The outer casing, the insert, and the breakable joining portion may be made of the same material.

[0049] In some embodiments, the method for manufacturing a turbomachine blade according to the present invention includes at least one assembly step. The assembly step may include an assembly between the outer casing 10 and the breakable connecting portion 20 and / or an assembly between the outer casing 10 and the insert 30.

[0050] The breakable junction part helps to reduce deformations associated with additive manufacturing, for example by supporting the outer shell and the insert relative to each other, thus facilitating the manufacturing of the blade.

[0051] The breakable junction part thus ensures the formation of the air passage which allows the blade to be cooled.

[0052] In some embodiments, the process includes a step of mounting the turbomachine blade in a turbomachine and a rupture step, the rupture step comprising at least one of the rupture of the breakable junction portion, the rupture between the breakable junction portion and the outer casing and the rupture between the breakable junction portion and the insert, and the rupture step being prior to the step of mounting the turbomachine blade in the turbomachine.

[0053] Fracture can be achieved by applying stress to the blade, for example, on the insert or the outer casing. Fracture can also be achieved by any other method, such as applying a thermal gradient or by chemical attack. When fracture is achieved before the blade is mounted in the turbomachine, the blade can be handled. freely, which provides access to numerous methods. The process can thus be optimized according to needs, including in terms of time and costs, while ensuring that the break actually takes place.

[0054] By creating the rupture before the blade is mounted in the turbomachine, the outer casing and the insert are geometrically independent from the moment of installation, so that the thermo-mechanical displacements between the hot and cold zones are independent from the moment the blade is mounted in the turbomachine. The blade is thus compatible with nominal turbomachine operation from the moment it is installed.

[0055] In some embodiments, the process includes a step of mounting the turbomachine blade in a turbomachine and a rupture step, the rupture step comprising at least one of the rupture of the breakable junction portion, the rupture between the breakable junction portion and the outer casing and the rupture between the breakable junction portion and the insert, and the rupture step being subsequent to the step of mounting the turbomachine blade in the turbomachine.

[0056] The failure can be achieved by applying a stress to the blade, for example, by starting the turbomachine at a predefined load level. When the failure occurs after the blade has been mounted in the turbomachine, no prior failure step is necessary, which simplifies blade operation. Failure takes place with the blade mounted if required; otherwise, it means that the stresses are below a failure design threshold and therefore do not compromise the integrity of either the outer casing or the insert. Brief description of the drawings

[0057] Other features and advantages of the object of this presentation will emerge from the following description of embodiments, given by way of non-limiting examples, with reference to the attached figures.

[0058] [Fig. 1] Figure 1 is a half-section view of a turbomachine including a blade.

[0059] [Fig. 2] Figure 2 is a schematic representation in a cross-sectional view of a blade according to one embodiment.

[0060] [Fig. 3A] Figure 3A is a schematic representation of a blade according to the embodiment in a cross-sectional view along section plane III of Figure 2.

[0061] [Fig. 3B] Figure 3B is a schematic representation of the blade of Figure 3A after breakage.

[0062] [Fig. 4A] [Fig. 4B] [Fig. 4C] [Fig. 4D] [Fig. 4E] [Fig. 4E] [Fig. 4F] Figures 4A, 4B, 4C, 4D, 4E and 4F are schematic views of breakable junction parts according to distinct embodiments. Description of the implementation methods

[0063] FIG 1 represents a turbomachine 101 in a longitudinal half-section along a plane passing through its main axis A1 -A1. The turbomachine 101 is a twin-body, twin-flow turbomachine, but other turbomachines can accommodate a blade according to an embodiment.

[0064] The turbomachine 101 comprises, from upstream to downstream according to the circulation of the airflow, a blower 102, a low pressure compressor 103 (also called "booster" in English), a high pressure compressor 104, a combustion chamber 105, a high pressure turbine 106, and a low pressure turbine 107. These different elements are installed inside a nacelle 120, so as to obtain a propulsion unit comprising the nacelle 120 and the turbomachine 101.

[0065] Downstream of the blower 102, the airflow is divided into a first part of the airflow (also called primary flow) F1 passing through the low pressure compressor 103, and a second part of the airflow (also called secondary flow) F2 flowing in a bypass around the low pressure compressor 103.

[0066] The blower 102 and the low-pressure compressor 103 are driven by the low-pressure turbine 107 via a low-pressure main shaft SL, while the high-pressure compressor 104 is driven by the high-pressure turbine 106 via a high-pressure main shaft SH. The low-pressure main shaft SL typically extends inside the high-pressure main shaft SH.

[0067] A high-pressure turbine distributor blade 106 will be described with respect to figures 2, 3A and 3B.

[0068] The leaf 1 comprises an intrados wall 11 and an extrados wall 12. The intrados wall 11 and the extrados wall 12 form an outer envelope 10.

[0069] The intrados wall 11 and the extrados wall 12 delimit an internal volume of the external envelope 10.

[0070] Optionally, openings 18 can be formed in the outer casing 10, allowing air to circulate from the inner volume to the outside of the outer casing 10, in order to cool the outer casing 10 by film cooling. In other embodiments, the section of the outer casing 10 can be closed along the entire height of the blade 1.

[0071] Optionally, the outer envelope 10 can be discontinuous along the height direction of the blade 1.

[0072] An insert 30 is provided in the inner volume of the outer envelope 10. The insert 30 can, for example, extend all along the blade 1 in the general direction in which the blade 1 extends.

[0073] Transverse to the general direction in which the blade 1 extends, the insert 30 is formed so as to leave an air passage 40 between the insert 30 and the outer casing 10.

[0074] In the cross-sectional view of Figure 2, the air passage 40 is formed between the insert 30 and the outer casing 10 all around the insert 30. It is understood that the insert 30 and the outer casing 10 can, however, be locally in contact, direct or indirect, and that an air passage 40 can be formed between the insert 30 and the outer envelope 10.

[0075] The outer envelope 10 can be cooled by air circulating in the air passage 40, for example by forced internal convection of this air.

[0076] In this case, a circulation of cold air within the air passage 40 makes it possible to extract heat from the outer envelope 10, and thus maintain the temperature of the outer envelope 10 at temperature levels limiting the premature aging of the outer envelope 10.

[0077] Alternatively or in addition, the cooling of the outer envelope 10 can be achieved by impacting jet.

[0078] In this case, the insert 30 is hollow and a cold air circulation is provided inside the insert 30, and openings 38, for example in the form of through holes, are provided in the insert 30 in order to evacuate the cold air circulating inside the insert 30 towards the external envelope 10 opposite the openings 38, that is to say here from the inside of the insert 30 towards the air passage 40.

[0079] The outer casing 10 is made of a material with good mechanical resistance at high temperatures. Preferably, this material is also compatible with formation by additive manufacturing processes, for example, a powder bed fusion additive manufacturing process.

[0080] Preferably, the entire blade 30 is made of the same material.

[0081] Such a material is for example a nickel-based alloy, for example alloys known under the following trade names: René® 77 (with mass composition Ni 58%; Cr 15%; Co 15%; Al 4.3%; Mo 4.2%; Ti 3.3%; Fe 0.4%; C 0.17%; Si 0.1%; Mn 0.1%); Inconel® 939 (with a mass composition of Cr 22.5%; Co 19.0%; W 2.0%; Nb 1.0%; Ti 3.7%; Al 1.9%; Ta 1.4%; Zr 0.1%; C 0.15%; B 0.01%, the remainder being composed of Ni and unavoidable impurities); or Inconel® 738 (mass composition Cr 16%; Co 8.5%; Al 3.4%; Ti 3.4%; W 2.6%; Mo 1.8%; Fe 0.5%; Si 0.3%; Mn 0.2%; C 0.17%).

[0082] The blade 1 includes at least one breakable junction part 20, connected on one side to the insert 30 and on the other side to the outer casing 10.

[0083] The structure of the breakable junction part 20 will be detailed in relation to figures 3A to 4F.

[0084] The outer envelope 10 comprises a plurality of breakable joining parts 20 distributed all around the insert 30 in a transverse plane, preferably regularly distributed all around the insert 30 in a transverse plane.

[0085] For example, two successive breakable junction parts 20 along the direction of airflow are separated by a distance d between 0.2 mm and 3 mm, preferably between 0.4 mm and 1 mm.

[0086] The breakable junction parts 20 of the plurality of breakable parts may have a similar structure, as in the example of Figures 3A and 3B. Figure 3A shows the breakable junction parts 20 before rupture, while Figure 3B shows these same breakable junction parts 20 after rupture under the effect of thermomechanical stresses.

[0087] However, it is understood that the breakable junction parts 20 of the plurality of breakable junction parts 20 may have different structures from each other, for example each having one or more of the characteristics described below with respect to the breakable junction parts of the embodiments of figures 4A to 4F.

[0088] At least one of the mechanical resistance to breakage of the breakable junction part 20, the mechanical resistance to breakage between the breakable junction part 20 and the outer casing 10 and the mechanical resistance to breakage between the breakable junction part 20 and the insert 30 is less than the mechanical resistance to breakage of the outer casing 10 and the mechanical resistance to breakage of the insert 30.

[0089] In the case where the mechanical resistance to breakage of the breakable part of the junction 20 is the lowest among these mechanical resistances, in the event of application of a stress causing breakage, the breakage takes place within the breakable part of the junction 20.

[0090] In the case where the mechanical resistance to breakage between the breakable junction part 20 and the outer envelope 10 is the lowest among these mechanical resistances, in the event of application of a stress causing breakage, the breakage takes place at the interface between the breakable junction part 20 and the outer envelope 10.

[0091] In the case where the mechanical resistance to breakage between the breakable part of the junction 20 and the insert 30 is the lowest among these mechanical resistances, in the event of application of a stress causing breakage, the breakage takes place at the interface between the breakable part of the junction 20 and the insert 30.

[0092] In these three cases, the break does not take place within the outer envelope 10 or within the insert 30, so that the integrity of the outer envelope 10 and the insert 30 is preserved.

[0093] Figure 3A represents three breakable junction parts 20 provided between the outer envelope 10 and the insert 30 before breakage.

[0094] In this example, the mechanical resistance to breakage of the breakable part of the junction 20 is the lowest, so that the application of a stress causing breakage results in a break within the breakable part of the junction 20, as shown in Figure 3B.

[0095] Figures 4A to 4F represent different embodiments of breakable junction parts 20 provided between the outer envelope 10 and the insert 30.

[0096] The breakable junction part 20 has a length L between 0.2 mm and 2 mm, preferably 0.5 mm and 1 mm.

[0097] The length L is measured between two ends of the breakable junction part 20 respectively connected to the insert 30 and to the outer envelope 10.

[0098] The outer envelope 10 may have a local reinforcement 15 at the point where it connects with the breakable junction part 20.

[0099] As a complement or replacement, the insert 30 may have a local reinforcement 35 at the point of its connection with the breakable junction part 20.

[0100] These local reinforcements 15, 35 notably increase the breaking strength of the insert 30 and / or the outer casing 10, and thus ensure that the break is located within the breakable junction part 20 or at the interface with the insert 30 or the outer casing 10. Furthermore, although the breakable junction part 20 can be designed to concentrate stresses, the local reinforcements 15, 35 prevent the transmission of these stresses to the outer casing 10 and / or the insert 30.

[0101] As shown in the embodiments of figures 4A to 4F, the local reinforcements 15,35 can take the form of an extra thickness.

[0102] As shown in Figure 4A, the breakable junction part 20 may comprise two parts forming between them an angle 0 less than 90°, preferably less than 45°.

[0103] Such an angle makes it possible to create a zone of stress concentration within the breakable part of the junction 20, and thus ensure a break within the breakable part of the junction 20.

[0104] Preferably, the connection between the two parts forming angle 0 is free of rounding or fillet, in order to concentrate the stresses more within the breakable part of the junction 20.

[0105] The breakable junction part 20 has a thickness e measured along a direction transverse to the breakable junction part 20.

[0106] The thickness e, or at least the minimum thickness e, is less than the thickness of the outer envelope 10 and the thickness of the insert 30; the thickness of the outer envelope 10 and the thickness of the insert 30 being measured along their respective thickness directions.

[0107] Such thicknesses make it possible to control the propagation of the rupture zone, to control the disturbance of the airflow by the breakable part of the junction 20 and to control the speed of the airflow through the air passage 40.

[0108] The minimum thickness e of the breakable part of the joint 20 is less than 0.5 mm, preferably less than 0.3 mm, preferably equal to 0.2 mm.

[0109] Preferably, the thickness e of the breakable part of the joint 20 is greater than 0.5 mm, preferably greater than 0.3 mm, with the optional exception of a single continuous zone where the thickness e is minimal.

[0110] This allows the creation of a single area of ​​stress concentration that could lead to failure, and ensures the mechanical strength of the rest of the breakable part of the junction 20.

[0111] The thickness e of the breakable junction part 20 can be minimal in a central part of the breakable junction part 20, as in the embodiment of figures 4B and 4C.

[0112] In the embodiment of Figure 4B, the thickness e of the breakable junction part 20 decreases linearly from the two ends of the breakable junction part 20 to a central part of the breakable junction part 20, where the thickness e is minimal.

[0113] In the embodiment of Figure 4B, the minimum thickness e can be the smallest thickness e compatible with the manufacturing process of the blade 1 for which the breakable junction part 20 can be in one piece so as to ensure the geometric continuity of the outer envelope 10 and the insert 30.

[0114] In the embodiment of Figure 4C, the thickness e of the breakable junction portion 20 decreases non-linearly, for example in a concave, from both ends of the breakable junction part 20 to a central part of the breakable junction part, where the thickness e is minimal.

[0115] In the embodiments of figures 4A to 4C, the thickness e is minimal in a central part of the breakable junction part 20. The eventual breakage thus preferentially takes place in the central part of the breakable junction part 20, and is thus circumscribed to the breakable junction part 20.

[0116] The breakable junction portion 20 can also be symmetrical, for example exhibiting central symmetry or planar symmetry with respect to a plane transverse to the breakable junction portion 20. This further increases the chances that the break will be contained in the center of the breakable junction portion 20, and in particular that the break will not propagate to the outer envelope 10 or the insert 30.

[0117] As illustrated in the embodiments of Figures 4D, 4E and 4F, the thickness e of the breakable junction part 20 can be minimal in a peripheral part of the breakable junction part 20, for example at an interface between the breakable junction part 20 and the outer casing 10 or at an interface between the breakable junction part 20 and the insert 30. The eventual break thus preferentially takes place at the connection which is associated with the minimum thickness e among the connection between the breakable junction part 20 and the outer casing 10 and the connection between the breakable junction part 20 and the insert 30, i.e. a break located between the breakable junction part 20 and the outer casing 10 or between the breakable junction part 20 and the insert 30.

[0118] It is understood that the breakable part of the junction 20 can have various shapes, straight or curved, in one part or in several parts forming an angle 0 between them.

[0119] In the embodiments shown in Figures 4A to 4F, openings 18 are formed in the outer casing 10 and openings 38 are formed in the insert 30. The openings 18 and 38 can be arranged in a staggered pattern, as illustrated, or opposite each other, or in any other suitable arrangement. It is understood that only the openings 18 in the outer casing 10 or only the openings 38 in the insert 30 can be provided in the blade 1, or that the blade can be devoid of openings 18 in the outer casing 10 and openings 38 in the insert 30.

[0120] In all the embodiments described above, the geometric continuity, which is not necessarily a continuity of shape, between the outer shell 10 and the insert 30 achieved by the breakable junction part 20 makes it easier to manufacture the blade 1, in particular by manufacturing processes using additive methods, notably powder bed additive manufacturing.

[0121] The breakable junction part 20 can then ensure the support of the outer envelope 10 and the insert 30 relative to each other during manufacturing and compliance with manufacturing constraints.

[0122] The control of fracture resistance within the breakable junction portion 20 or at its interface with the outer casing 10 or the insert 30 can also be achieved by locally modifying the manufacturing parameters to create localized weakness, for example, localized material degradation, or by locally introducing defects, such as porosity. In the case of powder bed fusion additive manufacturing, localized weakness can, for example, be introduced by locally modifying the laser power and / or the laser scanning speed on one or more consecutive layers.

[0123] Once blade 1 has been manufactured, it can be mounted in a turbomachine 101, either as is or after ad hoc post-processing.

[0124] During the life of the blade 1 and due to the dimensioning of the breakable junction part 20, either a stress causing the breakage will cause a localized break in the breakable junction part 20 or at its interface with the outer envelope 10 or the insert 30, or such a level of stress will never be reached and no breakage will occur.

[0125] In both cases, the integrity of the outer envelope 10 and the insert 30 will not be compromised.

[0126] It may also be advantageous to voluntarily apply a controlled force causing the break in the breakable junction part 20 or at its interface with the outer casing 10 or the insert 30 in order to further ensure that the break is effectively localized and / or circumscribed to the breakable junction part 20 or to one of its interfaces with the insert 30 and the outer casing 10, and thus prevent damage to the blade 1.

[0127] In this case, the force causing the breakage can be applied before or after the mounting of the blade 1 in the turbomachine 101.

[0128] Blade 1 has a structure that is particularly well-suited to production using additive manufacturing processes. A manufacturing process for blade 1 can therefore be implemented, entirely or partially, using additive manufacturing, for example, a laser powder bed fusion process.

[0129] In the embodiments of Figures 3A to 4F, the breakable junction part 20 has been shown extending substantially between two positions of the outer envelope 10 and the insert 30 located opposite each other, the outer envelope 10 and the insert 30 being substantially planar and parallel.

[0130] It is understood that any other shape and / or orientation of the outer casing 10, of the breakable junction part 20 and / or of the insert 30 compatible with the operation of the blade 1 within the turbomachine 101 can be provided.

[0131] Optionally, the shape and / or orientation of the outer casing 10, the breakable connecting portion 20, and / or the insert 30 can be specifically designed to be compatible with the additive manufacturing process for the blade 1, for example, by extending in a direction substantially parallel to the manufacturing direction and / or by having cantilevered material volumes that do not cause a manufacturing defect. Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments.Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Demands

1. Turbomachine blade (1) comprising: an outer casing (10) comprising an intrados wall (11) and an extrados wall (12) delimiting between them an inner volume, an insert (30) disposed in the inner volume so as to form an air passage (40) between the insert (30) and the outer casing (10); and at least one breakable connecting portion (20), connected on one side to the insert (30) and on the other side to the outer casing (10); in which at least one of the mechanical resistance to breakage of the breakable junction part (20), the mechanical resistance to breakage between the breakable junction part (20) and the outer casing (10) and the mechanical resistance to breakage between the breakable junction part (20) and the insert (30) is less than the mechanical resistance to breakage of the outer casing (10) and the mechanical resistance to breakage of the insert (30).

2. Turbomachine blade (1) according to claim 1, wherein the blade (1) is a turbomachine high-pressure distributor blade (1).

3. Turbomachine blade (1) according to claim 1 or 2, wherein the breakable junction part (20) has a length between 0.2 mm and 2 mm, preferably between 0.5 mm and 1 mm.

4. Turbomachine blade (1) according to any one of claims 1 to 3, wherein the breakable junction part (20) has a minimum thickness of less than 0.5 mm, preferably less than 0.3 mm.

5. Turbomachine blade (1) according to any one of claims 1 to 4, wherein the breakable connecting part (20) comprises a first part and a second part connected to each other at an angle of less than 90°, preferably less than 45°.

6. Turbomachine blade (1) according to any one of claims 1 to 5, wherein at least one of the insert (30) and the outer casing (10) is locally reinforced at its connection with the breakable junction part (20).

7. Turbomachine blade (1) according to any one of claims 1 to 6, comprising a plurality of breakable joining parts (20) arranged along an airflow direction within the air passage (40).

8. Turbomachine blade (1) according to claim 7, wherein the distance between two successive breakable junction parts (20) along the direction of airflow is between 0.2 mm and 3 mm, preferably between 0.4 mm and 1 mm.

9. Turbomachine (101) comprising a turbomachine blade (1) according to any one of claims 1 to 8.

10. Method of manufacturing a turbine blade (1) according to any one of claims 1 to 8, comprising at least one powder bed additive manufacturing step.

11. A manufacturing method according to claim 10, comprising a step of mounting the turbomachine blade (1) in a turbomachine and a breaking step, wherein the breaking step comprises at least one of the breaking of the breakable junction part (20), the breaking between the breakable junction part (20) and the outer casing (10) and the breaking between the breakable junction part (20) and the insert (30); and the breaking step is prior to the step of mounting the turbomachine blade (1) in the turbomachine.

12. A manufacturing method according to claim 10, comprising a step of mounting the turbomachine blade (1) in a turbomachine and a breaking step, wherein the breaking step comprises at least one of the breaking of the breakable junction part (20), the breaking between the breakable junction part (20) and the outer casing (10) and the breaking between the breakable junction part (20) and the insert (30); and the breaking step is subsequent to the step of mounting the turbomachine blade (1) in the turbomachine.

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