Seal for a turbine engine

Abstract

The present application relates to an annular seal comprising a plurality of sealing sectors circumferentially distributed around a longitudinal axis (A), each sealing sector comprising an inner annular sector (30) connected to an outer annular sector by a return member, the inner annular sector (30) comprising: a core (31); an outer upstream platform (32) and an inner upstream platform (34) both extending in an upstream direction from the core (31) and radially spaced apart from each other; and an outer downstream platform and an inner downstream platform both extending in a downstream direction from the core (31) and radially spaced apart from each other.

Description

Technical Field

[0001] This disclosure relates to the design of seals for turbine engines, and to turbine engines including such seals. Background Technology

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. In fact, various countries have adopted, are adopting, or will adopt restrictions on carbon emissions. In particular, an ambitious standard applies to both new and existing aircraft, requiring the implementation of technological solutions to bring them into compliance with current regulations. For many years, civil aviation has been actively contributing to the fight against climate change.

[0003] Technological research and development efforts have led to significant improvements in aircraft environmental performance. The applicant is considering factors influencing all phases of design and development to obtain more energy-efficient and environmentally friendly aerospace components and products, whose integration and use in civil aviation have modest environmental consequences, aiming to improve aircraft energy efficiency.

[0004] Against this backdrop, engine efficiency is constantly improving, which can sometimes affect the temperature of gases or structural components downstream of the combustion chamber. Controlling the temperature in the turbine is crucial for mechanical strength and managing expansion-related deformation.

[0005] French patent document FR 3 080 406 A1 describes nozzle guide vanes, wherein the vanes are hollow and adapted to receive airflow from cooling vanes drawn from a compressor.

[0006] Cooling air flowing to the turbine can be drawn from downstream of the compressor and radially inward relative to the combustion chamber. This airflow passes through three seals: a seal located downstream of the high-pressure compressor, called the "CDP" (Compressor Exhaust Pressure Seal); an inner seal called the "FIS" (Front Inner Seal); and an outer seal called the "FOS" (Front Outer Seal). These seals are typically labyrinth seals. Labyrinth seals consist of fins arranged on the rotor that interact with an abrasive material on the stator. This abrasive material can have a honeycomb cellular structure.

[0007] The disadvantage of this type of seal is that the friction between the fins and the abrasive material tends to wear down the abrasive material, and thus often increases the clearance between the rotor and stator. This leads to an increase in airflow through the seal. Depending on the seal involved (CDP, FIS, FOS), this means an increase or decrease in the airflow supplied to the turbine, thus deviating from the optimized target airflow value. The increased clearance between these seals and the rotor can have two main consequences: reduced turbine engine efficiency and insufficient turbine cooling.

[0008] Therefore, it is necessary to ensure that the flow rate through the seal remains constant throughout the seal's entire service life. Summary of the Invention

[0009] The present invention aims to provide a turbine engine seal that allows control of the flow rate of cooling air supplied to the turbine, independent of its service life.

[0010] Therefore, this document relates to an annular seal comprising a plurality of sealing sectors circumferentially distributed around a longitudinal axis, each sealing sector comprising an inner annular sector connected to an outer annular sector via a return member, the inner annular sector comprising: a core; an outer upstream platform and an inner upstream platform, both extending upstream from the core and radially spaced apart from each other; and an outer downstream platform and an inner downstream platform, both extending downstream from the core and radially spaced apart from each other.

[0011] This seal architecture differs from the labyrinth seal. The platform has surfaces (upper and lower surfaces, respectively) that increase the air contact surface area on the seal. The dynamic lift of the inner sector at these surfaces ensures a predetermined clearance with the internal rotor. This design of the inner ring sector therefore allows for hydrostatic self-adjustment of the inner ring sector's position relative to the rotor.

[0012] It is clear here that the seal in question is not a seal in the strict sense, meaning that air cannot pass through it, but rather a relative seal whose purpose is to allow a controlled amount of air to pass through.

[0013] It should be understood that the predetermined clearance is a "target" clearance, and under certain operating conditions of the seal, the clearance may vary slightly around the predetermined value. When the seal is in its equilibrium position, the predetermined clearance ensures that the airflow through the seal is the desired airflow. However, if the clearance increases or decreases, the seal will return to the predetermined clearance due to the spring-like behavior of the inner ring sector, which is ensured in particular by the return member and the airflow.

[0014] More specifically, if the gap between the seal and the rotor becomes smaller than the predetermined gap, air friction on the platform tends to move the inner ring sector, thus increasing the gap. Conversely, if the gap between the seal and the rotor becomes larger than the predetermined gap, the force applied by the return member is greater than the dynamic lift of the platform, and the inner ring sector then returns to its equilibrium position, i.e., returns to the predetermined gap.

[0015] This mechanical-aerodynamic balance, which adjusts the predetermined gap, also prevents any contact between the rotor and the seal, thus eliminating the wear problems encountered with conventional labyrinth seals.

[0016] The "circumferential distribution" of sealing sectors means that each sealing sector defines a portion of the seal's circumference, and together the group of sealing sectors forms a complete seal. Alternatively, the distribution is regular, and each sealing sector then represents an equal portion of the seal's circumference.

[0017] The terms "inner" and "outer," or interchangeably "internal" and "external," refer to the radial position relative to the central axis of the seal surrounding the sealing sector. "Upstream" and "downstream" are understood to refer to the mainstream direction in a turbine engine.

[0018] According to one embodiment, the inner ring sector includes an upstream lip that protrudes upstream from the upstream end of the inner upstream platform and tilts away from the outer upstream platform.

[0019] The lips diverge upstream, thereby capturing a larger volume of air and directing it radially into the chambers formed between the upstream platforms.

[0020] According to one embodiment, the upstream platforms are connected to each other by a central reinforcement located at the circumferential center of the inner ring sector and / or by two lateral reinforcements located at the circumferential ends of the inner ring sector, and / or the downstream platforms are connected to each other by a central reinforcement located at the circumferential center of the inner ring sector and / or by two lateral reinforcements located at the circumferential ends of the inner ring sector.

[0021] These reinforcements allow for structural strengthening and stabilization of the circumferential position of the inner ring sector, resulting in better control of the clearance between the seal and the rotor.

[0022] According to one embodiment, the return member is connected to the inner ring sector at its base located at the circumferential end of the outer downstream platform. Alternatively, the return member may be connected to the inner ring sector at its base located at the circumferential end of the outer upstream platform.

[0023] By connecting the return member to the circumferential end, a flexible return member that does not lose its elasticity due to fatigue can be used, thus maintaining good control of the clearance even when the seal wears.

[0024] According to one embodiment, the outer downstream platform has an outer surface and the outer upstream platform has an inner surface, the outer surface of the outer downstream platform being closer to the longitudinal axis than the inner surface of the outer upstream platform.

[0025] According to one embodiment, the inner ring sector includes a central outer lip that protrudes from the core and extends radially relative to the longitudinal axis.

[0026] The central lip forms an obstruction to airflow. It can extend radially over most of the space between the inner and outer ring sectors. Alternatively, it can be radially narrower. It can thus form a support surface for auxiliary sealing components.

[0027] In one embodiment, the seal further includes an auxiliary sealing member radially disposed between the inner and outer ring sectors and upstream of the return member, the auxiliary sealing member being supported on the central outer lip.

[0028] The auxiliary sealing member prevents air from passing radially through the seal axially above the inner ring sector. In other words, this auxiliary seal ensures that the only path allowing air to pass through the seal is the (controlled) gap between the inner surface of the inner ring sector and the outer surface of the rotor facing the seal.

[0029] The auxiliary sealing member can be selected, for example, from a brush seal, a set of tabs, or a gasket. It can be supported on the central outer lip upstream or downstream of the central outer lip.

[0030] According to one embodiment, the inner ring sector includes a central inner lip that extends radially relative to the longitudinal axis and protrudes from the core.

[0031] The inner lip forms an obstruction to airflow. When the gap is smaller than the predetermined gap, it increases the pressure at the interface between the seal and the rotor, thereby helping to push the seal radially outward and assisting in restoring the predetermined gap.

[0032] According to one embodiment, the axial length of the upstream platform is between 30% and 50% of the total axial length of the inner ring sector.

[0033] This ratio is considered sufficient for the platform to perform its hydrostatic functions without unnecessarily increasing the weight or size of the seals.

[0034] According to one embodiment, the axial length of the inner downstream platform is less than 40% of the total axial length of the inner ring sector, and the axial length of the outer downstream platform is at least equal to the axial length of the inner downstream platform.

[0035] In one embodiment, the radial thickness of the platform is greater than 1 mm.

[0036] The platform therefore has sufficient rigidity to ensure that the design of the return component and the dimensions of the platform are robust: a platform that is too thin may deform during use and prevent precise control of the gap during the service life of the seal.

[0037] In one embodiment, the outer ring sector forms an outer sleeve, and the inner ring sector has ends arranged end-to-end in the circumferential direction.

[0038] In this embodiment, the circumferential end of the inner ring sector can have an angle of inclination between 30° and 90° relative to the circumferential direction. Alternatively, the angle can be between 0° and 30°.

[0039] The tilting of the ends of the inner ring sector allows for a reduction in the gap between the two inner ring sectors, thereby improving the effectiveness of the seal.

[0040] In one embodiment, the seal includes 8 to 20 sealing sectors.

[0041] This range represents a good trade-off between too few sectors (which would result in sectors that are too heavy for the return component) and too many sectors (which would result in a large number of inter-sector gaps and therefore potential air leaks).

[0042] In one embodiment, the outer ring sector of the seal can be a single piece, such as a sleeve. In other words, there is no physical separation between two circumferentially continuous outer ring sectors.

[0043] In one embodiment, the sleeve can be a single unit, meaning it is made as a single piece without any connections. In this case, the corner portions of the sleeve will be considered as outer ring sectors.

[0044] The present invention also relates to a turbine engine, comprising: a high-pressure compressor; a combustion chamber; a high-pressure turbine; first, second, and third seals; and an air supply circuit for supplying cooling air to the high-pressure turbine, the air supply circuit including an air inlet located downstream of the high-pressure compressor, a channel separated from the inlet by the first seal, a housing separated from the channel by the second seal, an air injector for bringing air into the housing, a purge outlet separated from the housing by the third seal, and an air outlet from the housing for directing airflow to the high-pressure turbine, wherein at least one of the first, second, and third seals is according to one of the above embodiments.

[0045] Based on the intended locations, the first seal is the compressor exhaust pressure seal (CDP) located downstream of the high-pressure compressor, the second seal is the front inner seal (FIS), and the third seal is the front outer seal (FOS).

[0046] It has been found that the seal of the present invention allows for better clearance control than labyrinth seals throughout their service life, and thus ensures continuous turbine engine performance and effective turbine cooling throughout the entire service life of the seal. Attached Figure Description

[0047] Other features, details, and advantages will become apparent from the following detailed description and analysis of the accompanying drawings, in which: [ Figure 1 [This is a schematic cross-sectional view of a turbine engine;] [ Figure 2 [This is a cross-sectional view of the turbine cooling circuit;] [ Figure 3 [This is a front view of the seal according to the present invention;] [ Figure 4 [This is an isometric view of the upstream section of the inner ring sector;] [ Figure 5 [This is an isometric view of the downstream section of the inner ring sector;] [ Figure 6 [] is a cross-sectional view of the inner ring sector. Detailed Implementation

[0048] These figures schematically depict various aspects of the invention. Dimensions are not shown to scale: some dimensions have been enlarged to facilitate reading the figures and understanding the phenomena involved.

[0049] The axial direction is the direction of the longitudinal axis A of the turbine engine. The radial direction is perpendicular to and coplanar with direction A. The circumferential or tangential direction is orthogonal to both the axial and radial directions.

[0050] This invention is preferably applicable to the context of aircraft turbine engines. In this context, Figure 1 The cross-section of a turbofan engine 1 is schematically shown in a vertical plane passing through its longitudinal axis A. Along the airflow direction from upstream to downstream, it includes a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, and a low-pressure turbine 7. It should be understood that the invention is not limited to turbofan engines having this specific structure.

[0051] The air entering the turbine engine is cold. It is compressed by compressors 3 and 4, raising its temperature to approximately 500-600°C. When it leaves combustion chamber 5, the air is at a temperature of approximately 1500 to 2000°C. Therefore, turbines 6 and 7 receive very hot air and thus undergo deformation and thermal wear. One way to regulate turbine temperature is to draw in some cooler air radially inside combustion chamber 5 and in the last stage of compressor 4, and direct this air downstream to cool the turbine.

[0052] Figure 2 It indicates Figure 1 It is a part of the turbine engine, especially the combustion chamber and seals.

[0053] In the illustrated embodiment, this part of the turbine engine has three seals: compressor exhaust pressure seal 10 ("CDP"), front inner seal 12 ("FIS"), and front outer seal 14 ("FOS").

[0054] Figure 2 This is just one example configuration of the air cooling path in a turbine engine, and those skilled in the art will be able to identify the corresponding seals CDP, FIS, and FOS in other cooling circuit geometries.

[0055] In the illustrated embodiment, air inlet 9 allows air 16 to be drawn downstream of the last compressor disc. The air 16 drawn downstream of the last compressor disc first passes through seal 10, which is located radially inward relative to the inlet of combustion chamber 5.

[0056] Air 16 continues to flow in channel 11, which can be looped around axis A.

[0057] Air then passes through the second seal (front inner seal) 12 and enters the housing 13 arranged between the second seal 12 and the third seal (front outer seal) 14.

[0058] Air is also collected radially inside the combustion chamber 5. Injector 15 injects air from chamber 17, which is radially inside the combustion chamber, into housing 13.

[0059] Air 16 from the compressor and air from the ejector 15 converge at the housing 13. This air is then directed through outlet 19 from the housing 13 to the cooling circuit 18 of the first stage of the turbine 6. Seal 14 allows regulation of the air discharged from the housing 13 to the purge circuit 20, which is axially located between the nozzle guide vane 6.1 and the first rotating turbine wheel 6.

[0060] Flow 18 is designed to cool the turbine, especially the hollow blades and impeller of turbine 6.

[0061] The amount of air regulated by seals 10, 12, 14 is determined by the gap between these seals and the respective inner surfaces 22 facing the seals. In the illustrated embodiment, the surface 22 facing the seals 10, 12, 14 is the outer surface of the rotor assembly.

[0062] In the following text, the seal of the present invention will be described by the numeral 10, but it should be noted that the description of this seal may be applied alternatively to other seals 12, 14.

[0063] Figure 3 A front view of the seal 10 perpendicular to direction A is shown.

[0064] The seal 10 consists of sectors distributed around axis A in the circumferential direction T. Each sector represents a corner portion of a ring extending 360° around axis A. Each sector includes an inner annular sector 30, an outer annular sector 60, and a return member 62. The return member 62 is connected to the inner annular sector 30 at a base 64 and to the outer annular sector 60 at a base 66.

[0065] The seal 10 can be formed from 8 to 20 sectors.

[0066] The outer ring sector 60 can be formed together to form a single ring. In this case, the division into sectors is purely geometric. Alternatively, the outer ring sector 60 can be formed from separate components assembled together.

[0067] The return member 62 can be formed of two strips, the thickness of which is designed to impart a predetermined elasticity, for example, between 0.7 and 2.0 mm. The total thickness of the return member can be between 2.5 and 5.0 mm. It should be understood that different numbers of strips (1, 3, 4) or different elastic spring techniques can be used.

[0068] The inner ring sector is spaced 30 units apart by a distance e. This distance is... Figure 3 The size is exaggerated. It is as small as possible to limit air leakage between sectors without impeding the free radial movement of the inner annular sector 30. This distance can be less than 0.3 mm.

[0069] The seal can be a single unit, meaning that the inner ring sector 30, the outer ring sector 60, the return member 62, and the bases 64 and 66 can be formed as one piece.

[0070] The inner annular sector 30 is spaced apart from the rotor 22 by a gap j. The seal 10 is designed to ensure the predetermined gap j. The predetermined gap can be between 0.1 and 1.0 mm. It is preferably less than 0.2 mm. This gap corresponds to the target airflow for a given engine speed or load.

[0071] If the clearance j becomes too large during turbine engine operation, the return member 62 will tend to apply a radial force toward axis A to reduce the clearance j. Conversely, if the clearance j becomes too small, the pressure of the airflow through the interface between the inner annular sector 30 and the rotor 22 will increase and tend to push the inner annular sector 30 away from axis A.

[0072] Figure 4 and Figure 5 Upstream and downstream isometric views of an advantageous embodiment of the inner ring sector 30 are shown respectively.

[0073] The inner ring sector 30 may include a core 31, meaning a solid element forming the core of the inner ring sector 30 from which various structural elements of the inner ring sector 30 extend. In this example, the core 31 is bent about axis A.

[0074] The inner ring sector 30 may include an outer upstream platform 32 and an inner upstream platform 34. These platforms 32, 34 are curved to follow a curvature about axis A. They are located upstream of the core 31. They are radially spaced apart from each other. This forms a recess 36 between platforms 32, 34. The inner platform 34 may be slightly recessed axially, for example, 5 to 10% of the axial length of platform 32 (see...). Figure 6 ).

[0075] The inner ring sector 30 extends from one end (formed by surface 37) to the other circumferential end (formed by surface 39). Platforms 32 and 34 extend from one end 37 of the inner ring 30 to the other end 39.

[0076] The inner ring sector 30 can be reinforced by a reinforcing member connecting the outer upstream platform 32 to the inner upstream platform 34. The reinforcing member may include a central reinforcing member 38 disposed at the circumferential center of the inner ring sector 30, which may be substantially in the middle of the inner ring sector 30. The central reinforcing member 38 divides the recess 36 into two parts. Alternatively, the reinforcing member may include lateral reinforcing members 40 disposed at the circumferential ends of the inner ring sector 30. The recess 36 is thus circumferentially defined.

[0077] When the inner upstream platform 34 is axially recessed relative to the outer upstream platform 36, the reinforcements 38 and 40 may have upstream surfaces that are inclined between 30° and 80° relative to axis A.

[0078] The inner ring sector 30 may include an upstream lip 42 extending from the upstream end 34.3 of the inner upstream platform 34. The function of this lip is described below. The lip extends upstream in an open manner. It can form an angle between 30° and 60° relative to axis A. The tilt angle of the lip 42 may optionally be the same as the angle formed by the reinforcements 38, 40 with axis A.

[0079] The inner ring sector 30 may include a lip 44 that protrudes from the core 31 and extends radially outward from axis A.

[0080] From a downstream perspective, Figure 5 The inner ring sector 30 is shown to include an outer downstream platform 46 and an inner downstream platform 48. These platforms 46, 48 are curved to follow a curvature about axis A. They are located downstream of the core 31. The outer downstream platform 46 may be radially offset relative to the inner downstream platform 48. This forms a recess 50. Platforms 46, 48 extend from one end 37 of the inner ring 30 to the other end 39.

[0081] The inner ring sector 30 can be reinforced by a reinforcing member connecting the outer downstream platform 46 to the inner downstream platform 48. The reinforcing member may include a central reinforcing member 52 disposed at the circumferential center of the inner ring sector 30, which may be substantially in the middle of the inner ring sector 30. The central reinforcing member 52 divides the recess 50 into two parts. Alternatively, the reinforcing member may include lateral reinforcing members 54 disposed at the circumferential ends of the inner ring sector 30. The recess 50 is thus circumferentially defined.

[0082] The reinforcing members 38, 40, 52, and 54 have a thickness (in the circumferential direction) that can be between 1% and 10% of the circumferential length of the inner ring sector 30.

[0083] The inner downstream platform 48 may have a tapered inner surface, for example, forming a truncated cone 56.

[0084] The inner ring sector 30 may also include a central inner lip 58 that extends radially from the core 31 toward axis A.

[0085] In summary, the inner ring sector 30 includes: a core 31; an outer upstream platform 32 and an inner upstream platform 34, both extending upstream from the core 31 and spaced apart from each other radially; and an outer downstream platform 46 and an inner downstream platform 48, both extending downstream from the core 31 and spaced apart from each other radially.

[0086] Figure 4 and Figure 5 The presence of base 64 is also highlighted, returning to the attachment point of member 62. The base can advantageously be located at the circumferential end of the inner ring sector 30. Base 64 may consist of a radial overhang having a substantially cylindrical radial outer surface and rounded corners connecting to the outer surface of the outer downstream platform. Base 64 is shown here on the outer downstream platform 46, or it may be located on the outer upstream platform.

[0087] Figure 6 yes Figure 4 A cross-sectional view of the inner ring sector 30 in the plane marked VI.

[0088] The outer upstream platform 32 has an outer surface 32.1 and an inner surface 32.2. The thickness of the outer upstream platform 32, denoted as E32, is the distance between the outer surface 32.1 and the inner surface 32.2.

[0089] The inner upstream platform 34 has an outer surface 34.1 and an inner surface 34.2. The thickness of the inner upstream platform 34, denoted as E34, is the distance between the outer surface 34.1 and the inner surface 34.2.

[0090] The downstream platform 46 has an outer surface 46.1 and an inner surface 46.2. The thickness of the downstream platform 46, denoted as E46, is the distance between the outer surface 46.1 and the inner surface 46.2. The outer surface 46.1 of the downstream platform 46 may be closer to the longitudinal axis A than the inner surface 32.2 of the upstream platform 32.

[0091] The inner downstream platform 48 has an outer surface 48.1 and an inner surface 48.2. The thickness of the inner downstream platform 48, denoted as E48, is the distance between the outer surface 48.1 and the inner surface 48.2.

[0092] Thicknesses E32, E34, E46, and E48 can be greater than 1 mm.

[0093] The corresponding lengths of platforms 32, 34, 46, and 48 are denoted as L32, L34, L46, and L48. Length L34 is between 20% and 70% of the total axial length L of the seal, and preferably between 30% and 50%. The value of L can be between 10 and 50 mm. It is preferably greater than 15 mm. Length L32 is greater than or equal to L34.

[0094] The length L48 is less than 60% of the length L, and preferably less than 40%. The length L46 is greater than or equal to the length L48.

[0095] Recesses 36 and 50 have radial heights E36 and E50, respectively, greater than 1 mm. Their radial heights can be constant.

[0096] The auxiliary sealing member 59 can be supported on the outer central lip 44. The auxiliary sealing member 59 is indicated here by dashed lines. It extends from the outer upstream platform 32 to the outer ring sector ( Figure 3 (60 in the middle). It can be arranged upstream of the return component 62.

[0097] Auxiliary sealing components prevent from upstream ( Figure 6 Air (on the left side of the inner ring sector 30) passes radially and axially through the seal relative to the inner ring sector 30. In other words, this auxiliary sealing member ensures that the only path allowing air to pass through the seal is the (controlled) gap j between the inner surfaces 34.2, 48.2 of the inner ring sector 30 and the outer surface 22 of the rotor facing the seal, as shown. Figure 3 As shown. The auxiliary sealing component can be selected, for example, from a brush seal, a set of tabs, or a gasket.

[0098] The central outer lip 44 may have an upstream protrusion, which serves as a baffle 44.1, further enhancing the seal in this area.

[0099] The various inner and outer surfaces of platforms 32, 34, 46, and 48 increase the contact surface area with air and generate a dynamic lift effect on the inner ring sector 30.

[0100] The upstream lip 42 and the central inner lip 58 form an obstruction to the airflow, generating positive pressure on their inner surfaces. The upstream lip 42 relative to axis A ( Figure 6 The tilt (horizontal direction) can be between 30° and 60°. The radial clearance between the lip 42 and the rotor is greater than the radial clearance between the central inner lip 58 and the rotor to ensure an air buffering effect, making it easier for air to enter the chamber between the lip 42 and the lip 58 than to escape from it.

[0101] Downstream, the truncated cone 56 acts as a diffuser, restricting airflow through the seal. The inclination of the truncated cone relative to axis A can be between 20° and 45°. Too small an angle reduces the diffusion effect, while too large an angle reduces the dynamic lift on the inner annular sector 30. Although the lip 42 and the truncated cone 56 have their own local effects on the airflow, these elements also exhibit a synergistic effect in maintaining the mechanical balance of the inner annular sector 30, allowing it to maintain its orientation relative to axis A.

[0102] In a variant not shown, the inner ring sector 30 has neither an upstream platform nor a downstream platform.

Claims

1. An annular seal (10, 12, 14) comprising a plurality of sealing sectors (30, 60, 62, 64) circumferentially distributed around a longitudinal axis (A), each sealing sector comprising an inner annular sector (30) connected to an outer annular sector (60) via a return member (62), the inner annular sector (30) comprising: Core (31); The outer upstream platform (32) and the inner upstream platform (34) both extend upstream from the core (31) and are radially spaced apart from each other; as well as The outer downstream platform (46) and the inner downstream platform (48) both extend downstream from the core (31) and are radially spaced apart from each other.

2. The sealing element (10, 12, 14) according to claim 1, characterized in that, The inner ring sector (30) includes an upstream lip (42) that protrudes upstream from the upstream end (34.3) of the inner upstream platform (34) and slopes away from the outer upstream platform (32).

3. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The upstream platforms (32, 34) are connected to each other by a central reinforcement (38, 52) located at the circumferential center of the inner ring sector (30) and / or by two lateral reinforcements (40, 54) located at the circumferential ends (37, 39) of the inner ring sector (30), and / or the downstream platforms (46, 48) are connected to each other by a central reinforcement (38, 52) located at the circumferential center of the inner ring sector (30) and / or by two lateral reinforcements (40, 54) located at the circumferential ends (37, 39) of the inner ring sector (30).

4. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The return component (62) is connected to the inner ring sector (30) at the base (64) of the circumferential end (37, 39) of the outer downstream platform (46).

5. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The outer downstream platform (46) has an outer surface (46.1) and the outer upstream platform (32) has an inner surface (32.2). The outer surface (46.1) of the outer downstream platform (46) is closer to the longitudinal axis (A) than the inner surface (32.2) of the outer upstream platform (32).

6. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The inner ring sector (30) includes a central outer lip (44) that protrudes from the core (31) and extends radially relative to the longitudinal axis (A).

7. The seal (10, 12, 14) according to the preceding claim further includes an auxiliary sealing member (59) arranged radially between the inner ring sector (30) and the outer ring sector (60) and arranged upstream of the return member (62), the auxiliary sealing member (59) being supported on the central outer lip (44).

8. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The inner ring sector (30) includes a central inner lip (58) that extends radially relative to the longitudinal axis (A) and protrudes from the core (31).

9. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The axial length (L32, L34) of the upstream platform (32, 34) is between 30% and 50% of the total axial length (L) of the inner ring sector (30).

10. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The axial length (L48) of the inner downstream platform (48) is less than 60% and preferably less than 40% of the total axial length (L) of the inner ring sector (30), and the axial length (L46) of the outer downstream platform (46) is at least equal to the axial length (L48) of the inner downstream platform (48).

11. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The radial thickness (E32, E34, E46, E48) of the platform (32, 34, 46, 48) is greater than 1 mm.

12. A turbine engine (1), comprising: High-pressure compressor (4); Combustion chamber (5); High-pressure turbine (6); First, second, and third seals (10, 12, 14); and An air supply circuit (9-20) for supplying cooling air to the high-pressure turbine (6) includes an air inlet (9) located downstream of the high-pressure compressor (4), a passage (11) separated from the inlet (9) by a first seal (10), a housing (13) separated from the passage (11) by a second seal (12), an air injector (15) that brings air into the housing (13), a purge outlet (20) separated from the housing (13) by a third seal (14), and an air outlet (19) from the housing (13) that directs the airflow (18) to the high-pressure turbine (6). At least one of the first, second, and third seals (10, 12, 14) is a seal according to any one of claims 1 to 11.

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