Turbine blade, turbine and method for manufacturing such blade

Abstract

The invention relates to a turbine blade (1) comprising: a casing (10) comprising a pressure side wall (11) and a suction side wall (12) defining an internal volume therebetween; an insert (30) arranged in the internal volume so as to form an air passage (40) between the insert (40) and the housing (10); and at least one breakable connection portion (20), one side of which is connected to the insert (30) and the other side of which is connected to the housing (10); wherein at least one of a mechanical breaking force of the breakable connection portion (20), a mechanical breaking force between the breakable connection portion (20) and the housing (10), and a mechanical breaking force between the breakable connection portion (20) and the insert (30) is less than a mechanical breaking force of the housing (10) and a mechanical breaking force of the insert (30).

Description

Technical Field

[0001] The present disclosure relates to turbine blades, and in particular, to turbine high pressure nozzle blades. Background Art

[0002] Turbine high-pressure nozzle vanes are known which allow the hot gas flow leaving the combustion chamber to be directed to drive the turbine and are equipped with a cooling circuit so as to maintain the integrity of the vanes even at extreme operating temperatures.

[0003] With hollow blades, an insert is applied into the blade to allow for better distribution of the cooling airflow within the blade, resulting in better cooling of the blade. The insert can be attached at the tip or root of the blade, and then the insert and blade are freestanding over most of the height of the blade.

[0004] In order to optimize the geometry and reduce costs, it is advantageous to manufacture the blade and the insert together. However, the lack of material continuity between the insert and the outer part of the blade may subsequently lead to deformations that can cause cracks within the blade or even failure to meet manufacturing tolerances, resulting in poor cooling airflow. These problems associated with blade manufacturing are even more pronounced in the case of manufacturing by additive methods.

[0005] However, providing material continuity between the insert and the outer portion of the blade may result in the transfer of stresses between portions that are subject to extreme thermomechanical stresses during turbine operation, which may result in fractures within the blade, the insert and the outer portion of the blade. Summary of the invention

[0006] The present disclosure aims to propose a turbine blade, the manufacture of which is facilitated and the performance of which is not deteriorated during operation of the turbine.

[0007] To this end, the present disclosure relates to a turbine blade, comprising: a housing including a pressure side wall and a suction side wall, the pressure side wall and the suction side wall defining an interior volume in a straight line therebetween; an insert disposed within the interior volume so as to form an air passage between the insert and the housing; and at least one breakable connecting portion connected to the insert on the one hand and to the housing on the other hand; wherein At least one of the mechanical fracture resistance of the breakable connection part, the mechanical fracture resistance between the breakable connection part and the housing, and the mechanical fracture resistance between the breakable connection part and the insert is less than the mechanical fracture resistance of the housing and the mechanical fracture resistance of the insert.

[0008] The pressure side wall and the suction side wall may be joined at the leading edge on the one hand and at the trailing edge on the other hand. The cross section of the outer shell may be closed, for example viewed in a transverse section plane in the general direction in which the blade extends. The cross section of the outer shell may be substantially closed, for example closed except for local cooling openings, for example to allow cooling by air film.

[0009] An air passageway refers to a continuous volume between an inlet and an outlet, distinct from the inlet, allowing air or any other fluid to pass between the inlet and the outlet.

[0010] A break between two components refers to a complete break or a partial break in the connection between the two components. A break between two parts of a component refers to a complete break or a partial break between the two parts.

[0011] Mechanical fracture resistance refers to mechanical fracture resistance in response to thermal or mechanical stress (e.g., repeated or non-repeated simple or compound forces, particularly in tension, compression, shear and / or bending, or any other known loading mode known to those skilled in the art).

[0012] In the case of stresses involving breakable links, it is understood that the fracture resistance of the outer shell refers to the fracture resistance of the region of the outer shell that is also subject to said stresses, which generally surrounds the interface between the breakable link and the outer shell. Likewise, in the case of stresses involving breakable links, it is understood that the fracture resistance of the insert refers to the fracture resistance of the region of the insert that is also subject to said stresses, which generally surrounds the interface between the breakable link and the insert.

[0013] In other words, at least one of the mechanical fracture resistance of the breakable connecting portion, the mechanical fracture resistance between the breakable connecting portion and the housing, and the mechanical fracture resistance between the breakable connecting portion and the insert is less than the mechanical fracture resistance of the housing and the mechanical fracture resistance of the insert if the following conditions are met: - the mechanical fracture resistance of the breakable connection is less than the fracture resistance of the outer shell and the fracture resistance of the insert; and / or - the mechanical fracture resistance between the breakable connection and the housing is lower than the mechanical fracture resistance of the housing and the mechanical fracture resistance of the insert; and / or The mechanical fracture resistance between the breakable connection and the insert is lower than the mechanical fracture resistance of the outer shell and the fracture resistance of the insert.

[0014] In other words, after the stress occurs in the assembly formed by the breakable link, the housing and the insert, the possible fracture is limited to the breakable link, i.e. the fracture separates the breakable link into two pieces; and / or at at least one interface between the breakable link and the insert or the housing, i.e. the fracture separates the breakable link from the insert and / or the housing. Specifically, after the stress occurs in the assembly formed by the breakable link, the housing and the insert, the fracture does not occur in either the insert or the housing before the breakable link itself or one of its interfaces with the insert or the housing breaks.

[0015] For the sake of simplicity but without loss of generality, the term "breakage" will be used hereinafter to refer indiscriminately to the breakage of the breakable connection itself and / or the breakage between the breakable connection and the housing and / or the breakage between the breakable connection and the insert, unless specifically mentioned or the context gives the term "breakage" a different meaning.

[0016] The breakable connection allows the insert to be supported in the shell before breaking, ensuring the geometrical continuity of the shell and the insert, thus improving the manufacturability of the blade. This type of blade is particularly suitable for manufacture by additive manufacturing methods.

[0017] Geometric continuity refers to the material continuity within a component or component assembly, which is independent of the shape of the component or component assembly. In this case, whether the components are continuous with each other in shape, material, etc., they can be continuously passed from the shell to the insert via the breakable connection.

[0018] If mechanical or thermomechanical stresses lead to fracture, the fracture is localized and / or limited only to the breakable connection or one of its interfaces with the insert and the shell. Thus, fracture limited to the breakable connection allows preventing damage to the blade, in particular to the insert and the shell.

[0019] Once the blade is manufactured, the clean break also allows the insert to be geometrically independent from the outer shell, while keeping the outer shell at a distance from the insert, a distance that is particularly relevant for good cooling of the blade.

[0020] The fracture may occur after, in conjunction with or instead of one or more other damage conditions such as plasticization. The mechanical resistance associated with such other damage may serve as a substitute or supplement for the mechanical fracture resistance. For example, in the case of damage in the form of plasticization, the plasticization is localized and / or restricted to the breakable connection or one of its interfaces with the blade and the housing, thereby preventing damage to the blade, in particular to the insert and the housing.

[0021] Once the blade has been manufactured, damage such as complete or partial fracture or plasticization will also lead to a redistribution of stresses within the component, thereby preventing further undesired damage to the blade.

[0022] During the operation of the turbine, the temperature of the casing is higher than that of the insert, causing the casing (belonging to the so-called "hot" zone) and the insert (belonging to the so-called "cold" zone) to expand in a different way. This differential expansion can lead to the breaking of the breakable connection. Therefore, after the breaking, the independence of the casing and the insert allows to ensure the independence of the thermomechanical movements between the hot zone and the cold zone, thus preventing the risk of ruptures in the casing or in the associated insert due to the different movements between the hot zone and the cold zone.

[0023] Better manufacturability and limiting the fracture to the breakable link allow ensuring the integrity of the casing and the insert during the operation of the turbine, thus ensuring the cooling of the turbine blade, for example by internal forced convection or impingement jets. Furthermore, by increasing the flexibility of manufacturing, the presence of the breakable link allows obtaining more complex and higher performance blade designs, in particular in terms of cooling. This type of blade is therefore compatible with high temperature operation of the turbine, associated with high thermal performance.

[0024] In certain embodiments, the blade is a turbine high pressure nozzle blade.

[0025] The high-pressure nozzle receives the hot combustion gases from the combustion chamber. By increasing the cooling capacity of the high-pressure nozzle blades, the turbine can operate at high temperatures associated with high thermal performance.

[0026] However, it will be appreciated that the blades may be arranged at other locations of the turbine. For example, the blades may be blades of another nozzle, such as a low-pressure nozzle.

[0027] In certain embodiments, the length of the breakable connection portion is comprised between 0.2 mm and 2 mm, preferably between 0.5 mm and 1 mm.

[0028] The length of the breakable connection is measured in the direction of the linear spacing between the insert and the housing. Thus, the length of the breakable connection corresponds to the length between the breakable connection and the respective interface of the housing and the insert, i.e. also to the minimum distance separating said interfaces.

[0029] The length of the breakable link is one of the parameters that determines the good cooling of the casing by the impingement jet through the insert. The flow rate of air through the air passage depends on the cross section of the air passage, which depends on the length of the breakable link and the width of the air passage, the width being measured perpendicularly to the length direction of the breakable link and the general direction in which the blades extend.

[0030] Such a value of the length of the breakable connection ensures good cooling of the blade and in particular of the casing.

[0031] In some embodiments, the minimum thickness of the breakable connecting portion is less than 0.5 mm, preferably less than 0.3 mm. The minimum thickness is the minimum thickness assumed locally by the breakable connecting portion. Within the meaning of the present disclosure, the minimum thickness may also be located at the interface between the breakable connecting portion and at least one of the housing and the insert.

[0032] The thickness of the breakable link is measured in a direction transverse to the neutral fiber of the breakable link.

[0033] Such dimensions of the breakable connection allow providing the function of supporting the insert and the housing relative to each other while concentrating the stresses at the constriction associated with the minimum thickness, which allows confining the breakage in the breakable connection, in particular at the constriction.

[0034] In certain embodiments, the thickness is smallest where the transverse cross-section is smallest.

[0035] The transverse cross section is measured in a plane perpendicular to the neutral fiber of the breakable link. The minimum transverse cross section is the minimum transverse cross section locally assumed by the breakable link. Within the meaning of the present disclosure, the minimum transverse cross section may also be located at the interface between the breakable link and at least one of the housing and the insert.

[0036] Such dimensions of the breakable connection allow ensuring the function of supporting the insert and the housing while ensuring a stress concentration at the constriction associated with the smallest transverse section, allowing the breakage to be localized in the breakable connection, in particular at the constriction.

[0037] In some embodiments, the breakable connecting portion includes a first portion and a second portion, and the first portion and the second portion are connected together while forming an angle less than 90°, preferably less than 45°. Such an angle is easy to concentrate stress and provide a better breaking direction.

[0038] In certain embodiments, at least one of the insert and the housing is locally reinforced at its connection to the breakable connecting portion.

[0039] Local reinforcement of the connection to the breakable connecting portion refers to reinforcement at least in the zone acted upon during the application of stress on the breakable connecting portion.

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

[0041] This reinforcement further allows localized breaking of the breakable connection and limits the propagation of such breaking, thereby maintaining the integrity of the housing and / or insert.

[0042] The present invention also relates to a blade including a plurality of breakable connecting portions arranged along an air flow direction in an air passage.

[0043] The plurality of breakable connecting portions allows for better support of the insert and the housing in the direction of air flow.

[0044] In certain embodiments, the distance between two consecutive breakable connecting portions in the direction of the gas flow is comprised between 0.2 mm and 3 mm, preferably between 0.1 mm and 1 mm.

[0045] Such a distance allows ensuring the function of supporting the breakable link while allowing satisfying the manufacturability constraints. For example, in the case of manufacturing the blade by a method comprising an additive manufacturing step on a powder bed, such a distance allows ensuring the removal of the blade from the powder.

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

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

[0048] In certain embodiments, a turbine blade according to the invention is manufactured in one piece.The outer shell, the insert and the breakable connecting portion may be formed as a single component.

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

[0050] The breakable connecting portion allows to reduce deformations related to additive manufacturing, for example by supporting the shell and the insert relative to each other, thus facilitating the manufacturing of the blade.

[0051] Therefore, the connecting portion can be broken to ensure the formation of an air passage, thereby ensuring cooling of the blade.

[0052] In certain embodiments, the method includes the step of assembling the turbine blade in the turbine and the step of breaking, the breaking step including at least one of breaking of a breakable connecting portion, breaking between the breakable connecting portion and the casing, and breaking between the breakable connecting portion and the insert, and the breaking step is earlier than the step of assembling the turbine blade in the turbine.

[0053] Fracture can be achieved by applying stress to the blade, for example on the insert or the casing. Fracture can also be achieved by any other method, such as applying a thermal gradient or chemical attack. When fracture is done before assembling the blade in the turbine, the blade can be manipulated freely, which provides a variety of methods. Therefore, the method can be optimized as needed, including in terms of time and money, while ensuring that fracture does occur.

[0054] By completing the fracture prior to assembling the blade in the turbine, once assembled, the housing and the insert are geometrically independent of each other, and thus once the blade is assembled in the turbine, the thermomechanical motions between the hot and cold zones are independent of each other. Thus, once the blade is assembled in the turbine, the blade is compatible with the nominal operation of the turbine.

[0055] In certain embodiments, the method includes the steps of assembling the turbine blade in a turbine and a breaking step, the breaking step including at least one of breaking of a breakable connecting portion, breaking between the breakable connecting portion and the casing, and breaking between the breakable connecting portion and the insert, the breaking step being performed after assembling the turbine blade in the turbine.

[0056] The fracture can be achieved by applying stresses to the blade, for example by running the turbine at a pre-limited load level. When the fracture is done after the blade is assembled in the turbine, no previous fracture step is required, which facilitates the use of the blade. If necessary, the fracture occurs after the blade is assembled, otherwise, this means that the stress is less than the dimensional fracture threshold and does not endanger the integrity of either the casing or the insert. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Other features and advantages of the object of the present disclosure will emerge from the following description of an embodiment given by way of non-limiting example with reference to the accompanying drawings.

[0058] [ Figure 1 ] Figure 1 is a half-section view of a turbine including blades.

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

[0060] [ Figure 3A ] Figure 3A The blade according to this embodiment is Figure 2 Schematic cross-sectional view of section III.

[0061] [ Figure 3B ] Figure 3B yes Figure 3A Schematic diagram of the blade after it breaks.

[0062] [ Figure 4A ][ Figure 4B ][ Figure 4C ][ Figure 4D ][ Figure 4E ][ Figure 4E ][ Figure 4F ] Figure 4A , Figure 4B , Figure 4C , Figure 4D , Figure 4E and Figure 4F is a schematic diagram of a breakable connection portion according to various embodiments. DETAILED DESCRIPTION

[0063] Figure 1 A longitudinal half-section of the turbine 101 is shown in a plane passing through its main axis A1-A1. The turbine 101 is a twin-shaft twin-flow turbine, but other turbines may also accommodate blades according to one embodiment.

[0064] The turbine 101 includes, from upstream to downstream along the air flow cycle, a fan 102, a low-pressure compressor 103 (also called a "supercharger"), 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 in a nacelle 120 to obtain a propulsion assembly including the nacelle 120 and the turbine 101.

[0065] Downstream of the fan 102 , the airflow is divided into a first airflow portion F1 (also called a main flow) passing through the low-pressure compressor 103 and a second airflow portion F2 (also called a secondary flow) flowing around the low-pressure compressor 103 .

[0066] The fan 102 and the low pressure compressor 103 are driven by a low pressure turbine 107 via a main low pressure shaft SL, whereas the high pressure compressor 104 is driven by a high pressure turbine 106 via a main high pressure shaft SH. The main low pressure shaft LS usually extends inside the main high pressure shaft SH.

[0067] Will combine Figure 2 , Figure 3A and Figure 3B A blade 1 of a high-pressure turbine nozzle 106 is depicted.

[0068] The blade 1 comprises a pressure side wall 11 and a suction side wall 12. The pressure side wall 11 and the suction side wall 12 form an outer shell 10.

[0069] The pressure side wall 11 and the suction side wall 12 delimit the inner volume of the housing 10 .

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

[0071] Alternatively, the outer shell 10 may be discontinuous in the height direction of the blade 1 .

[0072] The insert 30 is arranged in the inner volume of the housing 10. The insert 30 may, for example, extend along the blade 1 in the general direction in which the blade 1 extends.

[0073] The insert 30 is formed transversely to the general direction in which the blade 1 extends so as to leave an air passage 40 between the insert 30 and the housing 10 .

[0074] exist Figure 2 In the transverse cross-sectional view of FIG, the air passage 40 is formed between the insert 30 and the housing 10 surrounding the insert 30. However, it can be understood that the insert 30 and the housing 10 can be in local contact directly or indirectly, and the air passage 40 can be formed between the insert 30 and the housing 10.

[0075] The housing 10 may be cooled by the air circulating in the air passage 40 , for example, by internal forced convection of the air.

[0076] In this example, the circulation of cool air within the air passage 40 allows heat to be extracted from the housing 10 , thereby maintaining the temperature of the housing 10 at a temperature level that limits premature aging of the housing 10 .

[0077] Alternatively or additionally, cooling of the housing 10 can be achieved by impinging jets.

[0078] In this case, the insert 30 is hollow, the cold air circulation is arranged on the inside of the insert 30, and an opening 38, for example in the form of a through hole, is arranged in the insert 30 so that the cold air circulating on the inside of the insert 30 is discharged to the housing 10 facing the opening 38, that is, here discharged from the inside of the insert 30 to the air passage 40.

[0079] The housing 10 is designed from a material having good mechanical resistance at high temperatures. Preferably, such a material is also compatible with materials formed by additive manufacturing methods (eg additive manufacturing methods on a powder basis).

[0080] Preferably, the entire blade 30 is designed from this same material.

[0081] Such materials are, for example, nickel-based alloys, such as the alloys known under the following commercial names: 77 (mass composition: nickel 58%; chromium 15%; cobalt 15%; aluminum 4.3%; molybdenum 4.2%; titanium 3.3%; iron 0.4%; carbon 0.17%; silicon 0.1%; manganese 0.1%); 939 (mass composition: chromium 22.5%; cobalt 19.0%; tungsten 2.0%; niobium 1.0%; titanium 3.7%; aluminium 1.9%; tantalum 1.4%; zirconium 0.1%; carbon 0.15%; boron 0.01%, the remainder consisting of nickel and unavoidable impurities); or 738 (mass composition: chromium 16%; cobalt 8.5%; aluminum 3.4%; titanium 3.4%; tungsten 2.6%; molybdenum 1.8%; iron 0.5%; silicon 0.3%; manganese 0.2%; carbon 0.17%);

[0082] The blade 1 comprises at least one breakable connection portion 20 connected on the one hand to the insert 30 and on the other hand to the casing 10 .

[0083] Will combine FIG. 3A to FIG. 4F The structure of the breakable connecting portion 20 will be described in detail.

[0084] The housing 10 comprises a plurality of breakable connecting portions 20 distributed around the insert 30 in a transverse plane, preferably regularly distributed around the insert 30 in a transverse plane.

[0085] For example, the distance between two continuous breakable connecting portions 20 along the air flow direction is 0.2 mm to 3 mm, preferably 0.4 mm to 1 mm.

[0086] The breakable connecting part 20 in the plurality of breakable parts may have a similar structure, such as Figure 3A and Figure 3B as shown in the example. Figure 3A The breakable connecting portion 20 is shown before breaking, and Figure 3B The same breakable joining portion 20 is shown after breaking under the influence of thermomechanical stress.

[0087] However, it is understood that the breakable connecting parts 20 in the plurality of breakable connecting parts 20 may have different structures from each other, each structure having, for example, the following related 4A to 4F One or more features related to the breakable connecting portion of an embodiment.

[0088] At least one of the mechanical fracture resistance of the breakable connecting part 20, the mechanical fracture resistance between the breakable connecting part 20 and the shell 10, and the mechanical fracture resistance between the breakable connecting part 20 and the insert 30 is less than the mechanical fracture resistance of the shell 10 and the mechanical fracture resistance of the insert 3.

[0089] In the case where the mechanical fracture resistance of the breakable connecting portion 20 is the weakest among these mechanical resistances, if stress causing fracture is applied, fracture occurs in the breakable connecting portion 20 .

[0090] In the case where the mechanical fracture resistance between the breakable connecting portion 20 and the housing 10 is the weakest of these mechanical resistances, if stress causing fracture is applied, fracture occurs at the interface between the breakable connecting portion 20 and the housing 10 .

[0091] In the case where the mechanical fracture resistance between the breakable connecting portion 20 and the insert 30 is the weakest of these mechanical resistances, if stress causing fracture is applied, fracture occurs at the interface between the breakable connecting portion 20 and the insert 30 .

[0092] In these three cases, no fracture occurs in the housing 10 or the insert 30, thereby maintaining the integrity of the housing 10 and the insert 30.

[0093] Figure 3A Three breakable connecting portions 20 are shown disposed between the housing 10 and the insert 30 prior to breaking.

[0094] In this example, the mechanical resistance to fracture of the breakable connecting portion 20 is the weakest, so the application of stress that causes fracture will cause fracture in the breakable connecting portion 20, such as Figure 3B shown.

[0095] 4A to 4F Different embodiments of a breakable connection portion 20 provided between the housing 10 and the insert 30 are shown.

[0096] The length L of the breakable connecting portion 20 is between 0.2 mm and 2 mm, preferably between 0.5 mm and 1 mm.

[0097] The length L is measured between both ends of the breakable connecting portion 20 connected to the insert 30 and the housing 10, respectively.

[0098] The outer shell 10 may have a local reinforcement 15 at the connection between the outer shell 10 and the breakable connecting portion 20 .

[0099] Additionally or alternatively, the insert 30 may have local reinforcements 35 at its connection with the frangible connection portion 20 .

[0100] These local reinforcements 15, 35 allow in particular to increase the fracture resistance of the insert 30 and / or the shell 10, thereby ensuring that the fracture is localized within the breakable link 20 or at the interface between it and the insert 30 or the shell 10. Furthermore, even if the breakable link 20 can be designed to concentrate stresses, the local reinforcements 15, 35 prevent these stresses from being transmitted to the shell 10 and / or the insert 30.

[0101] like 4A to 4F As shown in the embodiment of FIG. 5 , the local reinforcement 15 , 35 may take the form of additional thickness.

[0102] like Figure 4A As shown, the breakable connecting portion 20 may include two portions, and the angle θ formed between the two portions is less than 90°, preferably less than 45°.

[0103] Such an angle allows a stress concentration zone to be generated within the breakable connecting portion 20 , thereby ensuring breakage within the breakable connecting portion 20 .

[0104] Preferably, the connection between the two parts forming the angle θ has no rounding or grooves in order to further concentrate stress within the breakable connecting part 20 .

[0105] The breakable connecting portion 20 has a thickness e measured in a direction transverse to the breakable connecting portion 20 .

[0106] The thickness e, or at least the minimum thickness e, is smaller than the thickness of the outer shell 10 and the thickness of the insert 30; the thickness of the outer shell 10 and the thickness of the insert 30 are measured in their respective thickness directions.

[0107] Such a thickness allows controlling the propagation of the fracture zone, controlling the disturbance of the air flow by the breakable bond 20 , and controlling the air flow velocity through the air passage 40 .

[0108] The minimum thickness e of the breakable connecting portion 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 connection 20 is greater than 0.5 mm, preferably greater than 0.3 mm, optionally except for a single continuous area where the thickness e is minimal.

[0110] This allows creating a single stress concentration zone that may lead to fracture, while ensuring the mechanical strength of the rest of the breakable connecting portion 20 .

[0111] like Figure 4B and Figure 4C As shown in the embodiment of FIG. 1 , the thickness e of the breakable connecting portion 20 may be smallest at the central portion of the breakable connecting portion 20 .

[0112] exist Figure 4B In the illustrated embodiment, the thickness e of the breakable connecting portion 20 decreases linearly from both ends of the breakable connecting portion 20 to the central portion of the breakable connecting portion 20 , and the thickness e at the central portion of the breakable connecting portion 20 is the smallest.

[0113] exist Figure 4B In the embodiment of , the minimum thickness e may be the minimum thickness e compatible with the manufacturing method of the blade 1 , for which purpose the breakable connection portion 20 may be a single piece to ensure the geometrical continuity of the shell 10 and the insert 30 .

[0114] exist Figure 4C In the illustrated embodiment, the thickness e of the breakable connecting portion 20 decreases nonlinearly from both ends of the breakable connecting portion 20 to the central portion of the breakable connecting portion, for example, decreases in a concave manner, and the thickness e at the central portion of the breakable connecting portion is the smallest.

[0115] exist FIG. 4A to FIG. 4C In the embodiment of the present invention, the thickness e of the central portion of the breakable connecting portion 20 is the smallest. Therefore, possible breakage preferably occurs in the central portion of the breakable connecting portion 20 and is therefore confined within the breakable connecting portion 20.

[0116] The breakable link 20 may also be symmetrical, for example having a central symmetry or a plane symmetry relative to a plane transverse to the breakable link 20. This allows to further increase the probability that the break is contained in the center of the breakable link 20, in particular the break will not propagate to the housing 10 or the insert 30.

[0117] like Figure 4D , Figure 4E and Figure 4F As shown in the embodiment of the present invention, the thickness e of the breakable connecting portion 20 can be the smallest at the peripheral portion of the breakable connecting portion 20, for example, at the interface between the breakable connecting portion 20 and the housing 10 or at the interface between the breakable connecting portion 20 and the insert 30. Therefore, a possible fracture preferably occurs at a connection associated with the minimum thickness e in the connection between the breakable connecting portion 20 and the housing 10 and the connection between the breakable connecting portion 20 and the insert 30, that is, the fracture is located between the breakable connecting portion 20 and the housing 10 or between the breakable connecting portion 20 and the insert 30.

[0118] It should be understood that the breakable connecting portion 20 may have various shapes, either linear or curvilinear, and may be a single piece or several pieces forming an angle θ between them.

[0119] exist 4A to 4FIn the embodiment of the present invention, the openings 18 are formed in the shell 10 and the openings 38 are formed in the insert 30. The openings 18 and the openings 38 may be arranged in a staggered arrangement, as shown, or arranged face to face with each other, or even arranged according to any relevant arrangement. It should be understood that only the openings 18 of the shell 10 or only the openings 38 of the insert 30 may be provided in the blade 1, or even the blade may lack the openings 18 in the shell 10 and the openings 38 in the insert 30.

[0120] In all the embodiments described above, the geometrical continuity (not necessarily of shape) between the shell 10 and the insert 30 achieved by the breakable connection 20 allows facilitating the manufacture of the blade 1 , in particular by additive manufacturing methods, in particular on a powder bed.

[0121] The breakable bond 20 may then provide support of the housing and insert 30 relative to each other during manufacturing and meet manufacturing constraints.

[0122] Control of the fracture resistance within the breakable link 20 or at its interface with the housing 10 or insert 30 can also be achieved by locally modifying the manufacturing parameters to produce local brittleness, such as local degradation of the material or local integration of defects (e.g., porosity). In the case of additive manufacturing on a powder bed, for example, local brittleness can be introduced by locally modifying the power of the laser and / or the scanning speed of the laser only on one or several consecutive layers.

[0123] Once the blade 1 is manufactured, it can be assembled in the turbine 101 as is or after special post-processing.

[0124] During the life of the blade 1, due to the size of the breakable link 20, stresses causing fracture will either result in local fracture in the breakable link 20 or at its interface with the shell 10 or insert 30, or such stress levels will never be reached and fracture will not occur.

[0125] In both cases, the integrity of the housing 10 and the insert 30 is not compromised.

[0126] It may also be advantageous to actively apply a controlled force to cause a fracture in the breakable link 20 or its contact with the shell 10 or insert 30 to further ensure that the fracture is actually confined and / or limited to the breakable link 20 or one of its interfaces with the insert 30 and the shell 10, thereby preventing damage to the blade 1.

[0127] In this case, the force causing the fracture may be applied before or after the blade 1 is assembled into the turbine 101 .

[0128] The blade 1 has a structure that is particularly suitable for production by additive manufacturing methods.The manufacturing method of the blade 1 can then be carried out completely or partly by additive manufacturing, for example by a laser melting method on a powder bed.

[0129] exist FIG. 3A to FIG. 4F In the embodiment of FIG. 4 , the breakable connecting portion 20 is shown to extend substantially between two locations of the housing 10 and the insert 30 facing each other, the housing 10 and the insert 30 being substantially planar and parallel.

[0130] It should be appreciated that any other shapes and / or orientations of the casing 10 , breakable bond portion 20 , and / or insert 30 may be compatible with operation of the bucket 1 within the turbine 101 .

[0131] Optionally, the shape and / or orientation of the shell 10, the breakable connection portion 20 and / or the insert 30 can be specifically designed to be compatible with the manufacturing method of the blade 1 by additive manufacturing, for example by extending in a direction substantially parallel to the manufacturing direction and / or having a cantilevered material volume that does not cause manufacturing defects. Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes can be made to these examples without departing from the overall scope of the invention as defined by the claims. In particular, the various features of the different illustrated / mentioned embodiments can be combined in further embodiments. Therefore, the present description and the drawings must be considered in an illustrative and not restrictive sense.

Claims

1. A turbine blade (1), comprising: a housing (10) comprising a pressure side wall (11) and a suction side wall (12), the pressure side wall and the suction side wall defining an interior volume therebetween; an insert (30) arranged in the interior volume so as to form an air passage (40) between the insert (40) and the housing (10); as well as at least one breakable connecting portion (20) connected on the one hand to the insert (30) and on the other hand to the housing (10); wherein At least one of the mechanical fracture resistance of the breakable connecting portion (20), the mechanical fracture resistance between the breakable connecting portion (20) and the housing (10), and the mechanical fracture resistance between the breakable connecting portion (20) and the insert (30) is smaller than the mechanical fracture resistance of the housing (10) and the mechanical fracture resistance of the insert (30).

2. The turbine blade (1) according to claim 1, characterized in that The blade (1) is a turbine high-pressure nozzle blade (1).

3. The turbine blade (1) according to claim 1 or 2, characterized in that The length of the breakable connecting portion (20) is between 0.2 mm and 2 mm, preferably between 0.5 mm and 1 mm.

4. The turbine blade (1) according to any one of claims 1 to 3, characterized in that The minimum thickness of the breakable connecting portion (20) is less than 0.5 mm, preferably less than 0.3 mm.

5. The turbine blade (1) according to any one of claims 1 to 4, characterized in that The breakable connecting portion (20) comprises a first portion and a second portion, wherein the first portion and the second portion are connected together while forming an angle less than 90°, preferably less than 45°.

6. The turbine blade (1) according to any one of claims 1 to 5, characterized in that At least one of the insert (30) and the housing (10) is locally reinforced at a connection with the breakable connecting portion (20).

7. The turbine blade (1) according to any one of claims 1 to 6, characterized in that It comprises a plurality of breakable connecting parts (20) arranged in the air flow direction in the air passage (40).

8. The turbine blade (1) according to claim 7, characterized in that The distance between two consecutive breakable connecting parts (20) in the air flow direction is between 0.2 mm and 3 mm, preferably between 0.4 mm and 1 mm.

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

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

11. The manufacturing method according to claim 10, characterized in that: The method comprises the steps of assembling the turbine blade (1) into a turbine and breaking the turbine blade, wherein The breaking step includes at least one of breaking of the breakable connecting portion (20), breaking between the breakable connecting portion (30) and the housing (10), and breaking between the breakable connecting portion (20) and the insert (30); and The breaking step precedes the step of assembling the turbine blade (1) into a turbine.

12. The manufacturing method according to claim 10, characterized in that: The method comprises the steps of assembling the turbine blade (1) into a turbine and breaking the turbine blade, wherein The breaking step includes at least one of breaking of the breakable connecting portion (20), breaking between the breakable connecting portion (30) and the housing (10), and breaking between the breakable connecting portion (20) and the insert (30); and The breaking step occurs later than the step of assembling the turbine blade (1) into a turbine.

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