Sealing gasket for turbomachine

Abstract

The present document presents an annular sealing gasket comprising a plurality of gasket sectors distributed circumferentially around a longitudinal axis (A), each gasket sector comprising an inner ring sector (30) connected to an outer ring sector by a return member, the inner ring sector (30) comprising: a first circumferential end (37) and a second circumferential end; an external upstream cylindrical surface (32.1) extending circumferentially from the first circumferential end (37) to the second circumferential end; an external downstream surface (46.1) extending circumferentially at a distance from the first and second ends (37), the external downstream surface (46.1) having a first cylindrical surface (46.11) arranged at a first radial position and a second cylindrical surface (46.12) arranged at a second radial position distinct from the first radial position.Figure from the summary: Figure 4.

Description

Title of the invention: Sealing gasket for turbomachine technical field

[0001] This disclosure relates to the design of a seal for a turbomachine and to a turbomachine comprising such a seal. Prior art

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain less energy-intensive and more environmentally friendly aeronautical components and products, whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.

[0004] In this context, engine efficiency is constantly being improved, which sometimes impacts the temperature of the gases or structural elements downstream of the combustion chamber. Controlling turbine temperatures is essential for reasons of mechanical strength and to control expansion deformations.

[0005] Patent document FR 3 080 406 Al describes a turbine distributor in which the blades are hollow and are adapted to receive a flow of air cooling the blades and taken from the compressor.

[0006] The turbine cooling air can be drawn downstream of the compressor and radially below the combustion chambers. This airflow passes through three seals: a high-pressure downstream compressor seal, called a "CDP" (compressor discharge pressure); an internal seal, called a "FIS" (forward inner seal); and an external seal, called a "FOS" (forward outer seal). These seals are generally labyrinth seals. They are formed of blades arranged on the rotor which cooperate with an abradable element on the stator. The abradable element may have a honeycomb-type structure.

[0007] The drawback of this type of seal lies in the fact that the friction of the blades on the abradable material tends to damage the abradable material and consequently increase the clearance between the rotor and stator. This leads to an increase in the airflow through the seals. Depending on the seal in question (CDPD, FIS, FOS), this means an increase or decrease in the airflow supplied to the turbines and therefore a deviation from a target airflow value. Thus, the increased clearance between these seals and the rotors can have two major consequences: a reduction in the turbomachine's efficiency and insufficient turbine cooling.

[0008] Therefore, there is a need to ensure a consistency of the flow rates through the sealing joints over the entire life of the joints. Summary

[0009] The present invention aims to provide a turbomachine sealing gasket that allows control of the cooling air flow supplied to the turbines, regardless of its lifespan.

[0010] To this end, the present document relates to an annular sealing joint comprising a plurality of sealing sectors distributed circumferentially around a longitudinal axis, each sealing sector comprising an inner ring sector connected to an outer ring sector by a return member, the inner ring sector comprising: a first circumferential end and a second circumferential end; an external upstream cylindrical surface extending circumferentially from the first circumferential end to the second circumferential end; an external downstream surface extending circumferentially at a distance from the first and second ends, the external downstream surface having a first cylindrical surface arranged at a first radial position and a second cylindrical surface arranged at a second radial position distinct from the first radial position;and an external central lip arranged between the external upstream surface and the external downstream surface, the external central lip extending circumferentially from the first circumferential extremity to the second circumferential extremity.

[0011] Such a seal architecture differs from a labyrinth seal. The external upstream and external downstream surfaces form air bearing surfaces on the seal. The bearing capacity of the internal sector on these surfaces ensures that a predefined clearance is maintained with the internal rotor. The design of the internal ring sector thus allows for hydrostatic self-regulation of the position of the internal ring sector relative to the rotor.

[0012] It is evident that the sealing in question here is not a strict sealing in the sense that air could not pass through the sealing joint, but a relative sealing, the purpose of the sealing joint being to allow a controlled amount of air to pass through.

[0013] It is understood that the predefined clearance is a "target" clearance, and that it is possible for the clearance to vary slightly around the predefined clearance value under certain operating conditions of the seal. When the seal is in its equilibrium position, the predefined 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 predefined clearance relative to a spring-like behavior of the internal ring sectors, ensured in particular by the return elements and the airflow.

[0014] More specifically, if the clearance between the seal and the rotor becomes smaller than the predefined clearance, air friction at the interface between the rotor and the inner surface of the seal tends to displace the inner ring sector, thereby increasing the clearance. Conversely, if the clearance between the seal and the rotor becomes larger than the predefined clearance, the return element exerts a force greater than the lift of the inner ring sectors, causing the inner ring sectors to return to their equilibrium positions, i.e., to the predefined clearance. The stepped design of the first and second cylindrical surfaces makes it possible to limit the mass of the inner sector while maintaining equilibrium.

[0015] This mechanical-aerodynamic balance, which regulates a predefined clearance, also prevents any contact between the rotor and the seal, thus eliminating the wear problem encountered with conventional labyrinth seals. In particular, when cold, the observed clearance can be greater than in known designs.

[0016] The outer central lip forms an obstacle to air circulation. It can extend radially over a large part of the space between the inner and outer ring sectors. Alternatively, it can be radially narrower. It can thus form a bearing surface for a secondary sealing element.

[0017] The "circumferential distribution" of the joint sectors means that each joint sector defines a portion of the joint's circumference, and that all the joint sectors together make up the complete joint. Optionally, the distribution is regular, and each joint sector then represents an equal portion of the sealing joint's circumference.

[0018] The terms "internal" and "external," or interchangeably "inside" and "outside," refer to a radial position relative to the longitudinal central axis of the joint around which the joint sectors are arranged. "Upstream" and "downstream" are to be understood in the principal direction of flow in a turbomachine.

[0019] According to one embodiment, the external upstream surface has an axial length of between 40 and 45% of the total axial length of the inner ring sector and the external downstream surface has an axial length of between 50 and 70% of the total axial length of the inner ring sector.

[0020] Since the pressure is higher upstream of the seal, this length ratio ensures a balance of the seal and therefore control of the play between the seal and the rotor.

[0021] The total axial length of the sealing gasket can be greater than or equal to 15 mm.

[0022] According to one embodiment, a wall arranged at a circumferential end and a base intended to connect the return member to the inner ring sector circumferentially delimit the external downstream surface.

[0023] It is thus possible to limit edge effects and to properly control the flow of the fluid and therefore to properly control the clearance between the seal and the rotor.

[0024] According to one embodiment, an internal frustoconical surface moves away from the longitudinal axis at a downstream end of the internal ring sector.

[0025] This surface forms a diffuser that reduces the flow rate passing radially under the inner ring sector. This conical surface may be inclined at less than 15° to the longitudinal axis (moving away from the axis downstream) and / or may extend axially over less than 10% of the total axial length of the seal. These limitations prevent the diffuser from compromising the load-bearing capacity of the inner ring sector.

[0026] According to one embodiment, the inner ring sector comprises an upstream lip projecting upstream and towards the longitudinal axis, and an inner central lip projecting radially towards the longitudinal axis, the upstream lip and the inner central lip each having a respective distal end arranged at a respective radius, the radius of the distal end of the upstream lip being greater than the radius of the distal end of the inner central lip. The radii are measured with respect to the central axis of the turbomachine.

[0027] The radial clearance between the upstream lip and the rotor is therefore greater than that between the inner central lip and the rotor, thus ensuring an increase in pressure (air cushion), as air enters the space between the rotor, the upstream lip, and the inner central lip more easily than it escapes. The difference between the radial positions of the two distal ends can be between 0.2 and 0.6 mm for a seal with a length of 15 mm or more.

[0028] The internal central lip can be said to be "calibrating" in the sense that it can be one of the elements closest to the rotor.

[0029] In other words, the inner lip forms an obstacle to air circulation which, together with the upstream lip, when the gap is less than the predefined gap, allows to increase the pressure at the interface between the seal and the rotor, in order to help push the seal radially outwards and assist in restoring the predefined clearance.

[0030] According to one embodiment, a first cavity is formed between the proximal lip and the inner central lip, the axial length of the first cavity being between 40 and 70% of the total axial length of the inner ring sector. Preferably, this range is reduced to 50 to 60%.

[0031] This cavity is thus of sufficient size to create an increase in pressure under the inner ring sector without being too large, leaving room for other components of the ring sector (diffuser, inner cylindrical surface in particular).

[0032] According to one embodiment, a first thickness is defined by the distance separating the external upstream surface from the first cavity and a second thickness is defined by the distance between the first cylindrical surface and the first cavity, the second thickness being preferably less than the first thickness by at least 30%.

[0033] It is thus possible to lighten the internal sector and to design more precisely springs guaranteeing good control of the play during the life of the sealing joint.

[0034] According to one embodiment, the first and second thicknesses are greater than 1 mm.

[0035] Thus, the inner ring sector has sufficient rigidity to ensure that the design of the return element is robust: elements with thicknesses that are too thin could deform in use and could prevent the design of a return element and a ring sector geometry that allows precise control of the play during the life of the seal.

[0036] According to one embodiment, the distal end of the upstream lip is chamfered.

[0037] This chamfer allows only a small portion of the upstream airflow to be directed under the internal sector. The chamfer may be less than 0.2 mm in size.

[0038] According to one embodiment, the inner ring sector comprises a frustoconical front surface which forms with the upstream lip an angle greater than or equal to 90°.

[0039] The recess thus formed lightens the inner ring sector and allows the air arriving from upstream to flow back. The recess can be symmetrical in the sense that the upstream lip and the conical front surface are, in a longitudinal section, symmetrical with respect to the horizontal.

[0040] According to one embodiment, the inner ring sector comprises an internal downstream cylindrical surface with an axial length between 15 and 25% of the total axial length of the inner ring sector.

[0041] This downstream cylindrical surface allows the internal cavities of the ring sector to be pressurized and the lift of the internal ring sector to be increased, thus regulating the clearance with the rotor.

[0042] According to one embodiment, a second cavity is formed between the internal central lip and the internal downstream cylindrical surface, the axial length of the second cavity being less than 10% of the total length of the internal ring sector.

[0043] The second cavity makes it possible to lighten the ring sector without altering the airflow at the interface between the sealing gasket and the rotor.

[0044] According to one embodiment, a second cavity is formed between the inner central lip and the inner downstream cylindrical surface, and the distance separating the first cylindrical surface from the first cavity is equal to the distance separating the first cylindrical surface from the second cavity, and is equal to the distance separating the second cylindrical surface from the inner downstream cylindrical surface.

[0045] According to one embodiment, the sealing joint further comprises a secondary sealing element arranged radially between the inner ring sector and the outer ring sector and arranged upstream of the return element, the secondary sealing element being supported on the outer central lip.

[0046] The secondary sealing element prevents air from passing axially through the sealing gasket above the inner ring sector. In other words, such a secondary sealing element ensures that the only path allowing air to pass through the sealing gasket is the (controlled) clearance between the inner surface of the inner ring sector and the outer surface of the rotor opposite the gasket.

[0047] The secondary sealing element can, for example, be chosen from a brush seal, a set of tabs, or a tile. It can be supported upstream of the external central lip or downstream of the external central lip.

[0048] In one embodiment, the outer ring sectors form an outer ferrule and the inner ring sectors have ends arranged end-to-end in the circumferential direction.

[0049] In such an embodiment, the circumferential ends of the inner ring sectors may have an angle of inclination with respect to the circumferential direction of between 30° and 90°. Alternatively, the angle may be between 0° and 30°.

[0050] An inclination of the ends of the inner ring sectors makes it possible to reduce the existing play between two inner ring sectors, thus improving the efficiency of the sealing joint.

[0051] In one embodiment, the sealing joint comprises between 8 and 20 sealing sectors.

[0052] This range of values ​​constitutes a good compromise between too few sectors, synonymous with sectors that are heavy for the return mechanisms, and too many sectors, synonymous with many inter-sector gaps and therefore potential air leaks.

[0053] In one embodiment, the outer ring sectors of a sealing gasket may be a single piece, for example a ferrule. In other words, there is no physical separation between two circumferentially successive outer ring sectors.

[0054] In one embodiment, such a ferrule may be monolithic, that is, made in a single piece without joining. In such a case, an angular portion of the ferrule may be considered as a sector of the outer ring.

[0055] The invention also relates to a turbomachine comprising: a high-pressure compressor; a combustion chamber; a high-pressure turbine; a first, a second and a third sealing ring; and a cooling air supply circuit to the high-pressure turbine, the air supply circuit comprising an air inlet downstream of the high-pressure compressor, a duct separated from the inlet by the first sealing ring, a housing separated from the duct by the second sealing ring, an air injector opening into the housing, a purge outlet separated from the housing by the third sealing ring and an air outlet from the housing directing the airflow to the high-pressure turbine, at least one of the first, second and third sealing rings being in accordance with one of the embodiments described above.

[0056] Depending on the position envisaged, the first seal is a seal downstream of the high-pressure compressor (called "CDP" for "compressor discharge pressure" in English), the second seal is a forward inner seal (called "FIS" for "forward inner seal" in English) and the third seal is a forward outer seal (called "FOS" for "forward outer seal" in English).

[0057] It has been found that the sealing gaskets of the invention allow better control of the clearance during their lifetime than labyrinth sealing gaskets, and thus ensure maintenance of the turbomachine's performance and efficient cooling of the turbines throughout the life of the gasket. Brief description of the drawings

[0058] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0059] [Fig.1] is a schematic cross-sectional view of a turbomachine;

[0060] [Fig.2] is a cross-sectional view of a turbine cooling circuit;

[0061] [Fig.3] is a front view of a sealing joint according to the invention;

[0062] [Fig.4] is an upstream isometric view of an inner ring sector;

[0063] [Fig.5] is a downstream isometric view of an inner ring sector;

[0064] [Fig.6] is a cross-sectional view of an inner ring sector. Description of the implementation methods

[0065] The figures schematically depict various aspects of the invention. The dimensions are not shown to scale: some dimensions are enlarged to facilitate reading the drawings and understanding the phenomena involved.

[0066] The axial direction is that of the longitudinal axis of the turbomachine, denoted A. The radial direction is perpendicular and coplanar to the direction A. The circumferential or tangential direction is orthogonal to the axial direction and to the radial direction.

[0067] The present invention falls preferably within the field of turbomachinery for aircraft. As such, [Fig. 1] schematically represents, in cross-section along a vertical plane passing through its longitudinal axis A, a turbofan engine 1. It comprises, from upstream to downstream along the airflow path, 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 is understood that the invention is not limited to a turbomachine specifically with this structure.

[0068] The air entering the turbomachine is cold. It is compressed by compressors 3 and 4 and its temperature rises to approximately 500-600°C. At the outlet of the combustion chamber 5, the air is at a temperature of around 1500 to 2000°C. The turbines 6 and 7 therefore receive very hot air and are thus subject to deformation and thermal wear. One way to regulate the temperature of the turbines is to draw cooler air from below the combustion chamber 5 and at the level of the last stages of compressor 4, and to route this air downstream to cool the turbines.

[0069] Fig. 2 represents a portion of the turbomachine of Fig. 1, and in particular the combustion chamber and sealing gaskets.

[0070] In the embodiment shown, the turbomachine portion has three seals: a seal 10 downstream of the high-pressure compressor (“CDP”), an internal seal before 12 (“FIS”), and an external seal before 14 (“FOS”).

[0071] Fig. 2 is only one example of a configuration for an air cooling path in a turbomachine, and a person skilled in the art will be able to identify the respective CDP, FIS and FOS seals in other cooling circuit geometries.

[0072] In the illustrated embodiment, an 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 the sealing gasket 10, which is located radially below the inlet of the combustion chamber 5.

[0073] The air 16 continues its path in a conduit 11 which can be annular around the axis A.

[0074] The air then passes through a second seal (front internal sealing seal) 12 and opens into a housing 13 arranged between the second seal 12 and a third seal (front external sealing seal) 14.

[0075] Air is also taken from under the combustion chamber 5. Air injectors 15 from a cavity 17 under the combustion chamber open into the housing 13.

[0076] The air 16 from the compressor and that from the injectors 15 meet at the housing 13. This air is then directed to a cooling circuit 18 of the first stage of the turbine 6 via an outlet 19 of the housing 13. The seal 14 allows regulation of an air outlet from the housing 13 to a purge circuit 20, axially positioned between a distributor 6.1 and the first moving wheel of the turbine 6.

[0077] The flow 18 is intended to cool the turbine and in particular to cool the hollow blades of the turbine 6.

[0078] The quantities of air regulated by the seals 10, 12, 14 are dictated by the clearance between these seals and a respective internal surface 22 radially opposite the seals. In the embodiment shown, the surface 22 opposite the seals 10, 12, 14 is an external surface of a rotor assembly.

[0079] In the following, the sealing gasket of the invention will be described with the number 10, but it should be noted that what is described for this gasket can also, or alternatively, be applied to the other sealing gaskets 12, 14.

[0080] Fig. 3 shows a joint 10 in front view, perpendicular to direction A.

[0081] The joint 10 is composed of sectors which are distributed in a circumferential direction T around the axis A. Each sector counts as an angular part of a ring describing 360° around the axis A. Each sector comprises an internal annular sector 30, an external annular sector 60, and a return member 62. The return member 62 is linked to the internal annular sector 30 at a base 64, and the return member 62 is linked to the external annular sector 60 at a base 66.

[0082] The joint 10 can be formed from 8 to 20 sectors.

[0083] The external annular sectors 60 can together form a single ring. The sectoring is in this case purely geometric. Alternatively, the external annular sectors 60 can be formed from separate pieces, assembled together.

[0084] The return member 62 may be formed of two blades of a thickness designed to give them a predetermined elasticity, for example between 0.7 and 2.0 mm. The total thickness of the return member may be between 2.5 and 5.0 mm. It is understood that another number of blades (1, 3, 4) or another elastic spring technology may be used.

[0085] The internal annular sectors 30 are spaced apart from each other by a distance e. This distance is exaggerated in [Fig. 3]. It is as small as possible to limit air leakage between the sectors, without hindering the free radial movement of the internal annular sectors 30. This distance can be less than 0.3 mm.

[0086] The seal can be monobloc, that is to say that the inner ring sectors 30, the outer ring sectors 60, the return members 62 and the bases 64, 66 can be formed from a single piece.

[0087] The internal annular sectors 30 are spaced from a rotor 22 by a clearance j. The seal 10 is designed to ensure a predefined clearance j. The predefined clearance can be between 0.1 and 1.0 mm. It is preferably less than 0.2 mm. This clearance corresponds to a target airflow for a given engine speed or load.

[0088] If, during the operation of the turbomachine, the clearance j becomes too large, the return member 62 will tend to apply a force radially towards the axis A to reduce the clearance j. Conversely, if the clearance j becomes too small, the airflow passing through the interface between the inner ring sector 30 and the rotor 22 will increase in pressure and will tend to move the inner ring sector 30 away from the axis A.

[0089] Figures 4 and 5 illustrate an advantageous embodiment of the inner ring sector 30, in isometric view, respectively from the upstream and downstream sides. Figures 4 and 5 are described together in the following paragraphs.

[0090] The inner ring sector 30 extends circumferentially from one end materialized by the surface 37 on the [Fig.4] to another circumferential end materialized by the surface 39 of the [Fig.5].

[0091] The inner ring sector 30 may include an upstream portion 32 having an external upstream surface 32.1, cylindrical, and an internal upstream surface 32.2. This upstream portion extends from the circumferential end 37 to the circumferential end 39.

[0092] The upstream portion 32 includes a frontal surface 32.3 which can be inclined with respect to the axis A (and therefore frustoconical).

[0093] The inner ring sector 30 may include an upstream lip 42, the function of which will be described below. This lip extends upstream and towards axis A. The upstream lip 42 has a distal end 42.1 which may be chamfered.

[0094] The lip 42 and the front surface 32.3 can form an angle (a in [Fig. 6]) which can be greater than or equal to 90°. The lip 42 and the front surface 32.3 can each be inclined at an angle of at least 45° with respect to the longitudinal direction A.

[0095] The inner ring sector 30 may include an external central lip 44 which projects outwards from the external upstream surface 32.1.

[0096] Downstream of the lip 44, a downstream portion 46 comprises an external downstream surface 46.1 including a first cylindrical surface 46.11 and a second cylindrical surface 46.12. These cylindrical surfaces 46.11 and 46.12 have different radii. The second cylindrical surface 46.12 has a radius smaller than the radius of the first cylindrical surface 46.11. A connecting surface (46.13 in [Fig. 5]) connects the first cylindrical surface 46.11 to the second cylindrical surface 46.12.

[0097] Thus, the external central lip 44 is arranged between the external upstream surface 32.1 and the external downstream surface 46.1.

[0098] The external downstream surface 46.1 does not extend circumferentially over the entire circumferential length of the inner ring sector 30. The external downstream surface 46.1 is circumferentially delimited by a wall 48 at one end (39 in [Fig. 5]) and by the base 64 at the other end 37. The wall 48 rises radially to a height greater than that of the first cylindrical surface 46.11 and can rise to a height less than that of the external upstream surface 32.1. This has the effect of limiting aerodynamic disturbances (edge ​​effects) and thus providing a design that allows good control of the clearance between the seal and the rotor.

[0099] The thickness of the wall 48 can be substantially equal to that of the outer central lip 44.

[0100] The base 64 can be made up of a radial overthickness having a radially external surface substantially cylindrical and fillets connecting to the first and second cylindrical surfaces 46.11, 46.12.

[0101] The downstream portion 46 may have an internal frustoconical surface 56 moving away from the longitudinal axis A at a downstream end of the internal ring sector 30. The material thickness may be constant over the entire downstream portion 46 and an external conical surface 46.14.

[0102] Upstream of the frustoconical surface 56, and opposite the second cylindrical surface 46.12, there is an internal downstream cylindrical surface 57.

[0103] The inner ring sector 30 may also include an inner central lip 58, extending radially towards the axis A.

[0104] Upstream, a first cavity 53 is delimited by the upstream lip 42 and the internal central lip 58. Downstream, a second cavity 55 is formed axially between the internal central lip 58 and the cylindrical surface 57.

[0105] Fig. 6 is a cross-sectional view of the inner ring segment 30 in the plane marked VI in Fig. 4. The upstream is on the left and the downstream is on the right.

[0106] The air coming from the left of the figure meets a blocking zone formed by the lip 42 and the frontal surface 32.3.

[0107] The inclination of the upstream lip 42 with respect to axis A (horizontal direction in [Fig. 6]) can be between 30° and 60°. The angle formed with the front surface 32.3 can be greater than or equal to 90°. The axial length of the internal surface of the upstream lip 42 can be between 1 and 1.5 mm.

[0108] A portion of the air will move towards a radially external part of the inner ring sector 30.

[0109] A secondary sealing element 59 can support the outer central lip 44. The secondary sealing element 59 is shown here in dashed lines. It can extend from the upstream portion 32 to the outer ring sector (60 in [Fig. 3]). It can extend from the inner ring sector 30 to the outer ring sector 60 and be positioned upstream of the return element 62.

[0110] The secondary sealing element prevents air from upstream (on the left in [Fig. 6]) from passing axially through the seal radially above the inner ring sector 30. In other words, such a secondary sealing element ensures that the only path allowing air to pass through the seal is the (controlled) gap between the inner surface 32.1 of the inner ring sector 30 and the outer surface 22 of the rotor opposite the seal. The secondary sealing element can, for example, be selected from a brush seal, a set of tabs, or a shim.

[0111] The upstream portion 32 of the inner ring sector 30 has a thickness E32, the distance between the external upstream surface 32.1 and the first cavity 53 (or the internal surface 32.2).

[0112] The upstream portion 32 has an axial length L32, defined between the upstream end of the inner ring sector 30 and the central lip 44, which is between 40 and 45% of the total axial length L of the inner ring sector 30. The total length L can be between 10 and 50 mm and preferably be at least 15 mm.

[0113] In the external downstream part, the two cylindrical surfaces 46.11, 46.12 have respective radii RI and R2. The radii are measured with respect to axis A. RI is different from R2 and RI is greater than R2. In the illustrated case, RI is greater than R2. The difference between the two radii can be between 1 and 3 mm.

[0114] The thickness E46 of the downstream portion 46 is constant. That is to say, the distance between the second cavity 55 and the cylindrical surface 46.11 is equal to that between the surface 57 and the surface 46.12. The radial distance between the internal conical surface 56 and the external conical surface 46.14 is constant and is also equal to E46. The value of E46 may be greater than or equal to 1.5 mm. The value of E32 is greater than E46 and may preferably be at least 2 times or at least 3 times the value of E46. In In other words, the second thickness E46 is preferentially less than the first thickness E32 by at least 50%.

[0115] Thus, in one embodiment, the distance E46 separating the first cylindrical surface 46.11 from the first cavity 53 is equal to the distance E46 separating the first cylindrical surface 46.11 from the second cavity 55, and is equal to the distance E46 separating the second cylindrical surface 46.12 from the internal downstream cylindrical surface 57.

[0116] The downstream portion 46 has an axial length L46, defined between the central lip 44 and the downstream end of the inner ring sector 30, which is between 50 and 70% of the total axial length L of the inner ring sector 30.

[0117] The upstream lip 42 and the internal central lip 58 form a first cavity 53 between them. The upstream lip 42 extends to a radius R3 which is larger than the internal radius R4 of the internal central lip 58. Thus, air rushes into this cavity and creates pressure that pushes the ring sector 30 radially outwards when the clearance between the ring sector and the rotor 22 is too small. The axial length of the lip 58 can be between 1 and 1.5 mm. R3 can exceed R4 by 0.2 to 0.6 mm. The internal distal end 58.1 of the lip 58 can be chamfered.

[0118] The axial length L53 of the first cavity 53 can be between 40% and 70% of the total axial length L of the inner ring sector 30. It is preferably between 50% and 60% of L.

[0119] The axial length L55 of the second cavity 55 may be less than 10% of the total axial length L of the inner ring sector 30.

[0120] The first cavity 53 axially overlaps (partially) the surfaces 32.1 and 46.11. The surface 46.11 axially overlaps the first cavity 53 partially and axially overlaps the second cavity 55 completely.

[0121] The axial length L57 of the internal downstream cylindrical surface 57 can be between 15% and 25% of the total axial length L of the internal ring sector 30. Preferably this length is about 20% of the length L. The cylindrical surface 57 can have the same radius R4 as the internal central lip 58.

[0122] In general, L53 and L57 are particularly important for controlling the airflow that passes under the inner ring sector 30. The second cavity 55 can be of small axial length and is essentially intended to limit the weight of the assembly.

[0123] The angle formed by the diffuser 46.14, 56 may be less than 15°. The diffuser extends axially over less than 10% of the total axial length L.

[0124] The axial length of the lip 44 can be greater than or equal to 1 mm.

[0125] The radial height of the second cavity 55 (R1-E46-R4) may be less than 2 mm.

[0126] The various internal and external surfaces 32.1, 32.2, 46.1, 56, 57 multiply the contact surfaces with the air and create a lift effect on the inner ring sector 30.

Claims

Demands

1. Annular sealing gasket (10, 12, 14) comprising a plurality of gasket sectors (30, 60, 62, 64) distributed circumferentially around a longitudinal axis (A), each gasket sector comprising an inner ring sector (30) connected to an outer ring sector (60) by a return member (62), the inner ring sector (30) comprising: a first circumferential end (37) and a second circumferential end (39); an external upstream cylindrical surface (32.1) extending circumferentially from the first circumferential end (37) to the second circumferential end (39); an external downstream surface (46.1) extending circumferentially at a distance from the first and second extremities (37, 39), the external downstream surface (46.1) having a first cylindrical surface (46.11) arranged in a first radial position (RI) and a second cylindrical surface (46.12) arranged at a second radial position (R2) distinct from the first radial position (RI); an external central lip (44) arranged between the external upstream surface (32.1) and the external downstream surface (46.1), the external central lip (44) extending circumferentially from the first circumferential end (37) to the second circumferential end (39); and an internal frustoconical surface (56) extending away from the longitudinal axis (A) at a downstream end of the internal ring sector (30).

2. Joint according to claim 1, wherein the upstream external surface (32.1) has an axial length (L32) between 40 and 45% of the total axial length (L) of the inner ring sector (30) and the downstream external surface (46.1) has an axial length (L46) between 50 and 70% of the total axial length (L) of the inner ring sector (30).

3. Joint (10, 12, 14) according to any one of the preceding claims, wherein a wall (48) arranged at a circumferential end (39) and a base (64) intended to connect the return member (62) to the inner ring sector (30) circumferentially delimit the external downstream surface (46.1).

4. Joint (10, 12, 14) according to any one of the preceding claims, wherein the inner ring sector (30) comprises an upstream lip (42) projecting upstream and towards the longitudinal axis (A), and an inner central lip (58) projecting radially towards the longitudinal axis (A), the upstream lip (42) and the inner central lip (58) each having a respective distal end (42.1, 58.1) arranged at a respective radius (R3, R4), the radius (R3) of the distal end (42.1) of the upstream lip (42) being greater than the radius (R4) of the distal end (58.1) of the inner central lip (58).

5. Joint (10, 12, 14) according to claim 4, in which a first cavity (53) is formed between the upstream lip (42) and the internal central lip (58), the axial length (L53) of the first cavity (53) being between 40 and 70% of the total axial length (L) of the internal ring sector (30).

6. Joint (10, 12, 14) according to claim 5, wherein a first thickness (E32) is defined by the distance separating the external upstream surface (32.1) from the first cavity (53) and a second thickness (E46) is defined by the distance between the first cylindrical surface (46.11) and the first cavity (53), the second thickness (E46) being preferably less than the first thickness (E32) by at least 50%.

7. Joint (10, 12, 14) according to any one of claims 4 to 6, wherein the distal end (42.1) of the upstream lip (42) is chamfered.

8. Joint (10, 12, 14) according to any one of claims 4 to 7, wherein the inner ring sector (30) comprises a frustoconical front surface (32.3) which forms with the upstream lip (42) an angle (a) greater than or equal to 90°.

9. Joint (10, 12, 14) according to any one of the preceding claims, wherein the inner ring sector (30) comprises an internal downstream cylindrical surface (57) of an axial length (L57) between 15 and 25% of the total axial length (L) of the inner ring sector (30).

10. Joint (10, 12, 14) according to claim 9 in combination with any one of claims 5 to 9, wherein a second cavity (55) is formed axially between the inner central lip (58) and the inner downstream cylindrical surface (57), the axial length (L55) of the second cavity (55) being less than 10% of the total length (L) of the inner ring sector (30).

11. Joint (10, 12, 14) according to claim 10 in combination with claim 5, wherein a second cavity (55) is formed axially between the inner central lip (58) and the inner downstream cylindrical surface (57), and wherein the distance (E46) separating the first cylindrical surface (46.11) from the first cavity (53) is equal to the distance (E46) separating the first cylindrical surface (46.11) from the second cavity (55), and is equal to the distance (E46) separating the second cylindrical surface (46.12) from the inner downstream cylindrical surface (57).

12. Seal (10, 12, 14) according to any one of the preceding claims, further comprising a secondary 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 secondary sealing member (59) being supported on the outer central lip (44).

13. Turbomachine (1) comprising: a high-pressure compressor (4); a combustion chamber (5); a high-pressure turbine (6); a first, a second and a third sealing (10, 12, 14); and a cooling air supply circuit (9-20) to the high-pressure turbine (6), the air supply circuit comprising an air inlet (9) downstream of the high-pressure compressor (4), a conduit (11) separated from the inlet (9) by the first seal (10), a housing (13) separated from the conduit (11) by the second seal (12), an air injector (15) opening into the housing (13), a purge outlet (20) separated from the housing (13) by the third seal (14) and an air outlet (19) from the housing (13) directing the airflow (18) to the high-pressure turbine (6), at least one of the first, second and third seals (10, 12, 14) conforming to any one of claims 1 to 12.

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