Seal for a turbine engine

Abstract

The present document relates to an annular seal comprising a plurality of sealing sectors distributed circumferentially about a longitudinal axis (A), each sealing sector comprising an inner annular sector (30) connected to an outer annular sector by a return member, said inner annular sector (30) comprising: a first circumferential end (37) and a second circumferential end; a cylindrical outer upstream surface (32.1) extending circumferentially from the first circumferential end (37) to the second circumferential end; an outer downstream surface (46.1) extending circumferentially at a distance from the first and second ends (37), the outer downstream surface (46.1) having a first cylindrical surface (46.11) disposed at a first radial position and a second cylindrical surface (46.12) disposed at a second radial position different from the first radial position.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the design of a seal for a turbine engine, and to a turbine engine comprising such a seal. BACKGROUND

[0002] Climate change is a major issue of concern for numerous legislative and regulatory authorities worldwide. Indeed, countries have, are or will be adopting various carbon emission limitation measures. In particular, an ambitious standard applies to both new and in-service aircraft, requiring the implementation of technical solutions to make it compliant with current regulations. Civil aviation has been actively addressing climate change for many years.

[0003] Technical research and development efforts have led to significant improvements in the environmental performance of aircraft. The Applicant is considering factors affecting all stages of design and development to obtain more energy-efficient and environmentally friendly aeronautical components and products, the integration and use of which in civil aviation has a lesser impact on the environment, with the aim of increasing the energy efficiency of aircraft.

[0004] In this context, engine efficiency is constantly increasing, which sometimes affects the temperature of the gases or structural elements downstream of the combustion chamber. Controlling the temperature in the turbine is essential for mechanical strength and managing deformations associated with expansion.

[0005] French patent document FR 3 080 406 A1 describes a guide vane in which the vane is a hollow structure and is adapted to receive an air flow extracted from the compressor for cooling the vane.

[0006] Cooling air to the turbine can be extracted radially inside the combustion chamber as well as at the end of the compressor. This air flow passes through three seals: a seal downstream of the high-pressure compressor, called "CDP" (compressor discharge pressure seal), an inner seal called "FIS" (forward inner seal), and an outer seal called "FOS" (forward outer seal). These seals are generally labyrinth seals. The labyrinth seal is composed of fins arranged on the rotor, which interact with an abradable material on the stator. This abradable material can have a honeycomb structure.

[0007] The drawback of such a seal is that the friction between the fins and the abradable material tends to wear the material, with the result that the clearance between the rotor and the stator increases. This leads to an increase in the air flow passing through the seal. Depending on the seal concerned (CDP, FIS, FOS), this means an increase or a decrease in the air flow supplied to the turbine, thus deviating from the target air flow value. The increased clearance between these seals and the rotor therefore has two main consequences: a decrease in the efficiency of the turbine engine, and insufficient cooling of the turbine.

[0008] It is therefore necessary to ensure a constant flow through the seal throughout its lifetime. SUMMARY

[0009] The present invention aims to provide a turbine engine seal capable of controlling the flow of cooling air supplied to the turbine, regardless of its lifetime.

[0010] To this end, the present document relates to an annular seal 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; a cylindrical outer upstream surface extending circumferentially from the first circumferential end to the second circumferential end; an outer downstream surface extending circumferentially at a distance from the first end and the second end, the outer downstream surface having a first cylindrical surface arranged at a first radial position and a second cylindrical surface arranged at a second radial position different from the first radial position; and an outer central lip arranged between the outer upstream surface and the outer downstream surface, the outer central lip extending circumferentially from the first circumferential end to the second circumferential end.

[0011] Such a seal structure is different from a labyrinth seal. The outer upstream surface and the outer downstream surface form the surfaces against which the air rests on the seal. The dynamic pressure lift of the inner sectors on these surfaces ensures the maintenance of a predetermined gap with the internal rotor. The design of the inner ring sector thus makes it possible to carry out a hydrodynamic self-regulation of the position of the inner ring sector with respect to the rotor.

[0012] It should be made clear here that the seal in question is not a strict seal against which no air can pass, but rather a relative seal, the aim of which is to allow a controlled amount of air to pass.

[0013] It will be understood that this predetermined gap is a "target" gap, around which the gap can fluctuate slightly in certain operating conditions of the seal. This predetermined gap ensures a desired flow of air through the seal when the seal is in an equilibrium position. However, if the gap increases or decreases, the seal will return to the predetermined gap due to the spring-like behaviour of the inner ring sector, in particular ensured by the return member and the air flow.

[0014] More particularly, if the gap between the seal and the rotor becomes smaller than the predetermined gap, the air friction at the interface between the rotor and the inner surface of the seal tends to move the inner ring sector, thus increasing the gap. Conversely, if the gap between the seal and the rotor becomes greater than the predetermined gap, the force exerted by the return member is greater than the dynamic pressure lift of the inner ring sector, causing the inner ring sector to return to its equilibrium position, i.e. to the predetermined gap. The stepped design of the first cylindrical surface and the second cylindrical surface makes it possible to reduce the mass of the inner sector while maintaining the equilibrium.

[0015] This mechanical-pneumatic balancing of the intended gap also prevents any contact between the rotor and the seal, thus eliminating the wear problems encountered with traditional labyrinth seals. In particular, at cold state, the observed gap can be greater than in known designs.

[0016] The outer center lip forms an obstacle to the gas flow. It can extend radially a large part of the space between the inner and outer ring sectors. Alternatively, it can also have a narrow radial width. Thus, it can form a support surface for the secondary seal.

[0017] The "circumferential distribution" of the sealing sectors means that each sealing sector defines a portion of the circumference of the seal, and that the set of sealing sectors together make up the complete seal. Optionally, the distribution is uniform, in which case each sealing sector represents an equal portion of the circumference of the seal.

[0018] The terms "inner" and "outer", or synonymously "internal" and "external", are relative to the radial position with respect to the longitudinal central axis of the seal around which the sealing sectors are arranged. "Upstream" and "downstream" are understood as being in the direction of the main flow in a turbomachine.

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

[0020] This length ratio ensures the balancing of the seal, which controls the gap between the seal and the rotor, due to the higher pressure upstream of the seal.

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

[0022] In one embodiment, the wall provided at one circumferential end, and the base for connecting the return member to the inner ring sector, delimit the outer downstream surface in the circumferential direction.

[0023] This makes it possible to limit the edge effect and to precisely control the fluid flow, thus precisely controlling the gap between the seal and the rotor.

[0024] In one embodiment, the frustoconical inner surface extends away from the longitudinal axis at the downstream end of the inner ring sector.

[0025] This surface forms a nozzle, which can reduce the flow rate of the gas flow radially inside the inner ring sector. The angle of inclination of this conical surface with respect to the longitudinal axis can be less than 15° (inclined away from the axis in the downstream direction), and / or its extension in the axial direction can be less than 10% of the total axial length of the seal. These limits can prevent the nozzle from reducing the dynamic pressure lift 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 have a respective distal end, said distal ends being arranged at respective radii, the radius of the distal end of the upstream lip being greater than the radius of the distal end of the inner central lip. Said radii are measured with respect to the central axis of the turbine engine.

[0027] Thus, the radial space between the upstream lip and the rotor is greater than the radial space between the inner central lip and the rotor, thereby ensuring a pressure rise (air cushion) as it is easier for air to enter the space between the rotor, the upstream lip and the inner central lip than to escape. The difference between the two distal radial positions can be between 0.2 and 0.6 mm for a seal having a length of 15 mm or more.

[0028] The inner central lip can be described as "calibrated" as it can be one of the elements closest to the rotor.

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

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

[0031] Thus, the cavity is dimensioned so as to generate a pressure rise under the inner ring sector, without being too large so as to leave space for the other components of the ring sector, in particular the nozzle, the cylindrical inner surface.

[0032] In one embodiment, the first thickness is defined by the distance between the outer upstream surface and the first cavity, and the second thickness is defined by the distance between the first cylindrical surface and the first cavity, the second thickness preferably being at least 30% less than the first thickness.

[0033] This makes it possible to reduce the mass of the inner sector and to design the spring structure more precisely, ensuring good control of the gap throughout the service life of the seal.

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

[0035] The inner ring sector thus has sufficient rigidity to ensure that the design of the return member is robust: too thin an element can deform during use, thereby hindering the design of the return member and the ring sector geometry which is able to control the gap precisely throughout the service life of the seal.

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

[0037] This chamfering makes it so that only a small portion of the upstream airflow is directed under the inner ring segment. The chamfering size can be less than 0.2 mm.

[0038] In one embodiment, the inner ring segment comprises a truncated cone shaped front face forming an angle of greater than or equal to 90° with the upstream lip.

[0039] The recess thus created lightens the mass of the inner ring segment and redirects the air coming from upstream. This recess can be symmetrical, i.e. the upstream lip and the conical front face are symmetrical in a longitudinal section view with respect to the horizontal.

[0040] In one embodiment, the inner ring segment comprises a cylindrical inner downstream face whose axial length represents 15 to 25% of the total axial length of the inner ring segment.

[0041] This cylindrical downstream face pressurizes the inner cavity of the ring segment and increases the dynamic pressure lift of the inner ring segment, thus adjusting the clearance with the rotor.

[0042] In one embodiment, a second cavity is formed between the inner central lip and the cylindrical inner downstream face, the axial length of this second cavity being less than 10% of the total length of the inner ring segment.

[0043] This second cavity makes it possible to lighten the mass of the ring segment, while not modifying the airflow at the interface of the seal with the rotor.

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

[0045] According to one embodiment, the seal further comprises a secondary seal arranged in the radial space between the inner ring segment and the outer ring segment, upstream of the return member, the secondary seal abutting against the outer central lip.

[0046] This secondary seal prevents the passage of air axially with respect to the inner ring segment radially outside the seal. In other words, such a secondary seal ensures that the only path that allows air to pass through the seal is the (controlled) gap between the inner surface of the inner ring segment and the outer surface of the rotor facing the seal.

[0047] For example, the secondary seal can be chosen from a brush seal, a set of sealing sheets or gaskets. It can be supported upstream of the outer central lip or downstream of the outer central lip.

[0048] In one embodiment, the outer ring segment forms an outer collar, the ends of the inner ring segment being arranged end to end in the circumferential direction.

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

[0050] The inclination of the inner ring segment end makes it possible to reduce the gap present between two inner ring segments, thus improving the effectiveness of the seal.

[0051] In one embodiment, the seal comprises between 8 and 20 sealing segments.

[0052] This numerical range represents a good compromise: too few segments would result in segments that are too heavy, beyond the load capacity of the return means; too many segments would result in too many gaps between the segments, which could lead to air leakage.

[0053] In one embodiment, the outer ring segments of the seal can be a single piece, for example a collar. In other words, there is no physical separation between two circumferentially successive outer ring segments.

[0054] In one embodiment, such a collar can be a single body, i.e. manufactured as a single part without joints. In this case, one angular portion of the collar can be considered as an outer ring segment.

[0055] The application 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 comprising an air inlet located downstream of the high-pressure compressor, a channel separated from the inlet by the first seal, a chamber separated from the channel by the second seal, an air injector for introducing air into the chamber, a bleed outlet separated from the chamber by the third seal, and an air outlet for directing the air flow from the chamber to the high-pressure turbine, wherein at least one of the first, second and third seals is a seal according to any one of the embodiments described above.

[0056] Depending on the intended position, the first seal is a compressor discharge pressure seal (CDP) located downstream of the high-pressure compressor, the second seal is a forward inner seal (FIS) and the third seal is a forward outer seal (FOS).

[0057] It has been found that the seal of the application makes it possible to better control the gap throughout its service life than a labyrinth seal, thus ensuring the durability of the turbine engine performance and efficient turbine cooling throughout the service life of the seal. BRIEF DESCRIPTION OF DRAWINGS

[0058] Other features, details and advantages will become apparent from the following detailed description and from the analysis of the drawings, in which: Figure 1 is a schematic cross-sectional view of a turbine engine; Figure 2 is a cross-sectional view of a turbine cooling circuit; Figure 3 is a front view of a seal according to the present application; Figure 4 is an upstream direction isometric view of an inner ring segment; Figure 5 is a downstream direction isometric view of an inner ring segment; Figure 6 is a cross-sectional view of an inner ring segment. DETAILED DESCRIPTION

[0059] The accompanying drawings schematically depict various aspects of the application. The dimensions are not shown to scale; certain dimensions are exaggerated for the sake of legibility and understanding of the phenomena involved.

[0060] The axial direction is the direction of the longitudinal axis of the turbine engine, noted A. The radial direction is perpendicular and coplanar to the direction A. The circumferential or tangential direction is perpendicular to the axial and radial directions.

[0061] The application is preferably applicable to an aeronautical turbine engine. Thus, Figure 1 A cross-section of a turbofan engine 1 in a vertical plane perpendicular to the longitudinal axis A is schematically shown. From upstream to downstream in the direction of the airflow, it comprises 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 will be understood that the application is not limited to a turbine engine having this particular structure.

[0062] The air entering the turbine engine is cold. It is compressed by the compressors 3 and 4, the temperature rising to about 500-600°C. When the air leaves the combustion chamber 5, the temperature is about 1500 to 2000°C. The turbines 6 and 7 therefore receive very hot air and are subject to deformation and thermal wear by it. One way of regulating the temperature of the turbines is to extract a portion of cooler air from the radially inner side of the combustion chamber 5 and from the last stage of the compressor 4, and to direct this air downstream to cool the turbines.

[0063] Figure 2 A portion of the turbine engine is shown, in particular the combustion chamber and the seals. Figure 1 A portion of the turbine engine is shown, in particular the combustion chamber and the seals.

[0064] In the embodiment shown, this portion of the turbine engine has three seals: a compressor discharge pressure seal 10 (“CDP”), a forward inner seal 12 (“FIS”) and a forward outer seal 14 (“FOS”).

[0065] Figure 2 This is only one example configuration of an air cooling path in a turbine engine, the skilled person will be able to identify corresponding CDP, FIS and FOS seals in other cooling circuit geometries.

[0066] In the illustrated embodiment, the air inlet 9 allows extraction of air 16 downstream of the last compressor disc. The air 16 extracted downstream of the last compressor disc first passes through a seal 10 located radially inside the inlet of the combustion chamber 5.

[0067] The air 16 continues to flow in a channel 11 which can be annular around the axis A.

[0068] The air then passes through a second seal (front inner seal) 12 and enters a chamber 13 arranged between the second seal 12 and a third seal (front outer seal) 14.

[0069] The air is also collected radially inside the combustion chamber 5. An air injector 15 injects air from a chamber 17 located radially inside the combustion chamber into the chamber 13.

[0070] The air 16 from the compressor and the air from the air injector 15 are combined in the chamber 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 chamber 13. The seal 14 enables the air inside the chamber 13 to be regulated to a bleed circuit 20 which is arranged axially between the guide vanes 6.1 and the first stage rotating turbine disc 6.

[0071] The flow 18 is used to cool the turbine, in particular to cool the hollow blades and guide vanes of the turbine 6.

[0072] The amount of air regulated by the seals 10, 12, 14 is determined by the gap between these seals and the respective inner surface 22 facing the seals radially. In the illustrated embodiment, the surface 22 facing the seals 10, 12, 14 is the outer surface of the rotor assembly.

[0073] The seal of the invention will be described below with the number 10, but it should be noted that the description of this seal can additionally or alternatively apply to the other seals 12, 14.

[0074] Figure 3 A front view of the seal 10 perpendicular to the direction A is shown.

[0075] The seal 10 is composed of sectors distributed in a circumferential direction T around the axis A. Each sector represents one angular portion of an annulus extending 360° around the axis A. Each sector comprises an inner ring sector 30, an outer ring sector 60 and a return member 62. The return member 62 is connected to the inner ring sector 30 at a base 64 and the return member 62 is connected to the outer ring sector 60 at a base 66.

[0076] The seal 10 can be composed of 8 to 20 sectors.

[0077] The outer ring sector 60 can collectively form a single ring. In this case, the sector division is purely geometric. Alternatively, the outer ring sector 60 can be formed from independent components assembled together.

[0078] The return member 62 can be formed from two strips of thickness 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, or 4 strips) or different elastic spring technologies can be used.

[0079] The inner ring sector 30 is separated by a distance e. This distance is... Figure 3 The distance is exaggerated. This distance should be as small as possible to limit air leakage between fan segments without impeding the radial free movement of the inner ring fan segment 30. This distance can be less than 0.3 mm.

[0080] The sealing element can be a single piece, that is, the inner ring sector 30, the outer ring sector 60, the return component 62, and the bases 64 and 66 can be integrally formed.

[0081] The inner ring sector 30 is separated from the rotor 22 by a gap j. The seal 10 is designed to ensure a predetermined gap j. The predetermined gap can be between 0.1 and 1.0 mm, preferably less than 0.2 mm. This gap corresponds to the target airflow at a given engine speed or load.

[0082] 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 airflow pressure at the interface between the inner ring sector 30 and the rotor 22 will increase and tend to push the inner ring sector 30 away from axis A.

[0083] Figure 4 and Figure 5 An advantageous embodiment of the inner ring sector 30 is shown in isometric views of its upstream and downstream sides. The following paragraphs will describe this together. Figure 4 and Figure 5 .

[0084] Inner ring sector 30 from Figure 4 The circumferential end represented by surface 37 shown is... Figure 5 The surface 39 shown represents another circumferential end extending circumferentially.

[0085] The inner ring sector 30 may include an upstream portion 32 having a cylindrical outer upstream surface 32.1 and an inner upstream surface 32.2. The upstream portion extends from a circumferential end 37 to a circumferential end 39.

[0086] The upstream portion 32 includes a front surface 32.3 that can be tilted relative to axis A (and thus is truncated cone-shaped).

[0087] The inner ring sector 30 may include an upstream lip 42, the function of which is described below. This lip extends upstream and toward axis A. The upstream lip 42 has a chamfered distal end 42.1.

[0088] Lip 42 and front surface 32.3 can form an angle ( Figure 6 (α in the figure), the included angle can be greater than or equal to 90°. The lip 42 and the front surface 32.3 can each be tilted at least 45° relative to the longitudinal direction A.

[0089] The inner ring sector 30 may include an outer central lip 44 that protrudes outward from the outer upstream surface 32.1.

[0090] Downstream of lip 44, the downstream portion 46 includes an outer downstream surface 46.1, which comprises 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 radius of the second cylindrical surface 46.12 is smaller than the radius of the first cylindrical surface 46.11. (Connecting surface) Figure 5 (46.13) connects the first cylindrical surface 46.11 and the second cylindrical surface 46.12.

[0091] Therefore, the outer central lip 44 is disposed between the outer upstream surface 32.1 and the outer downstream surface 46.1.

[0092] The outer downstream surface 46.1 does not extend over the entire circumferential length of the inner ring sector 30. The outer downstream surface 46.1 extends at one end ( Figure 5 39) is defined circumferentially by wall 48 and at the other end 37 by base 64. Wall 48 rises radially to a height above the first cylindrical surface 46.11 and can rise to a height below the outer upstream surface 32.1. This has the effect of limiting aerodynamic disturbances (edge ​​effects), thus providing a design that allows for good control of the clearance between the seal and the rotor.

[0093] The thickness of the wall 48 can be approximately equal to the thickness of the outer central lip 44.

[0094] The base 64 may consist of a radially thicker portion having a generally cylindrical radial outer surface, and rounded corners connecting the first and second cylindrical surfaces 46.11, 46.12.

[0095] The downstream portion 46 may have a truncated conical inner surface 56 extending away from the longitudinal axis A at the downstream end of the inner ring sector 30. The thickness of the material may remain constant throughout the downstream portion 46 and the outer conical surface 46.14.

[0096] Upstream of the truncated conical surface 56, and opposite to the second cylindrical surface 46.12, is the inner downstream cylindrical surface 57.

[0097] The inner ring sector 30 may also include an inner central lip 58 extending radially toward axis A.

[0098] Upstream, the first cavity 53 is defined by the upstream lip 42 and the inner central lip 58. Downstream, the second cavity 55 is formed axially between the inner central lip 58 and the cylindrical surface 57.

[0099] Figure 6 yes Figure 4 A cross-sectional view of the inner ring sector 30 in the plane indicated by VI. The upstream is on the left and the downstream is on the right.

[0100] In the diagram, air from the left side encounters a blockage formed by lip 42 and front surface 32.3.

[0101] The angle of inclination of the upstream lip 42 relative to axis A ( Figure 6 The horizontal angle (in the middle) 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 inner surface of the upstream lip 42 can be between 1 and 1.5 mm.

[0102] Some of the air will be directed to the radially outer portion of the inner ring sector 30.

[0103] Secondary seal 59 abuts against outer center lip 44. Secondary seal 59 is indicated here by dashed lines. It can extend from upstream portion 32 to outer ring sector ( Figure 3 (60 in the middle). It can extend from the inner ring sector 30 to the outer ring sector 60 and is positioned upstream of the return component 62.

[0104] This secondary seal prevents contamination from upstream ( Figure 6 Air (on the left side of the middle section) passes axially relative to the inner ring sector 30 on the radially outer side of the seal. In other words, this type of secondary seal 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 facing the seal. This secondary seal can be, for example, a self-brushing seal, a set of sealing plates, or gaskets.

[0105] The upstream portion 32 of the inner ring sector 30 has a thickness E32, which is the distance between the outer upstream surface 32.1 and the first cavity 53 (or inner surface 32.2).

[0106] The upstream portion 32 has an axial length L32, which is defined as the portion between the upstream end of the inner ring sector 30 and the center lip 44, accounting for 40 to 45% of the total axial length L of the inner ring sector 30. The total length L can be between 10 and 50 mm, preferably at least 15 mm.

[0107] In the outer downstream section, two cylindrical surfaces 46.11 and 46.12 have radii R1 and R2, respectively. The radii are measured relative to axis A. R1 and R2 are different, and R1 is greater than R2. In the case shown, R1 is greater than R2. The difference between the two radii can be between 1 and 3 mm.

[0108] The thickness E46 of the downstream portion 46 is constant. This means that the distance between the second cavity 55 and the cylindrical surface 46.11 is equal to the distance between surfaces 57 and 46.12. The radial distance between the inner conical surface 56 and the outer conical surface 46.14 is also constant and 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 preferably at least twice or at least three times the value of E46. In other words, the second thickness E46 is preferably at least 50% smaller than the first thickness E32.

[0109] Therefore, in one embodiment, the distance E46 between the first cylindrical surface 46.11 and the first cavity 53 is equal to the distance E46 between the first cylindrical surface 46.11 and the second cavity 55, and is also equal to the distance E46 between the second cylindrical surface 46.12 and the inner downstream cylindrical surface 57.

[0110] The downstream portion 46 has an axial length L46, which is defined as the portion between the center lip 44 and the downstream end of the inner ring sector 30, accounting for 50% to 70% of the total axial length L of the inner ring sector 30.

[0111] An upstream lip 42 and an inner center lip 58 form a first cavity 53 between them. The upstream lip 42 extends to a radius R3, which is larger than the inner center lip 58's inner radius R4. Therefore, air rushes into this cavity and, when the gap between the annular fan section 30 and the rotor 22 is too small, generates pressure that pushes the annular fan section 30 radially outward. 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 inner distal end 58.1 of the lip 58 can be chamfered.

[0112] The axial length L53 of the first cavity 53 can account for 40% to 70% of the total axial length L of the inner ring sector 30. Preferably, it accounts for 50% to 60% of L.

[0113] The axial length L55 of the second cavity 55 can be less than 10% of the total axial length L of the inner ring sector 30.

[0114] The first cavity 53 (partially) overlaps axially with surfaces 32.1 and 46.11. Surface 46.11 partially overlaps axially with the first cavity 53 and completely overlaps with the second cavity 55.

[0115] The axial length L57 of the cylindrical inner downstream surface 57 may account for 15% to 25% of the total axial length L of the inner ring sector 30. Preferably, this length is about 20% of the length L. The cylindrical surface 57 may have the same radius R4 as the inner center lip 58.

[0116] Overall, L53 and L57 are particularly important for controlling airflow below the inner ring sector 30. The second chamber 55 may have a smaller axial length, primarily to limit the overall weight.

[0117] The included angle formed by nozzles 46, 14, and 56 can be less than 15°. The axial length of the nozzle is less than 10% of the total axial length L.

[0118] The axial length of lip 44 can be greater than or equal to 1 mm.

[0119] The radial height (R1-E46-R4) of the second cavity 55 can be less than 2 mm.

[0120] Various inner and outer surfaces 32.1, 32.2, 46.1, 56, and 57 increase the contact area with air and generate a dynamic pressure lift effect on the inner ring sector 30.

Claims

1. An annular seal (10, 12, 14) comprising a plurality of sealing segments (30, 60, 62, 64) circumferentially distributed around a longitudinal axis (A), each sealing segment comprising an inner annular segment (30) connected to an outer annular segment (60) via a return member (62), said inner annular segment (30) comprising: First circumferential end (37) and second circumferential end (39); A cylindrical outer upstream surface (32.1) extending circumferentially from the first circumferential end (37) to the second circumferential end (39). An outer downstream surface (46.1) extends circumferentially at a certain distance from the first and second ends (37, 39), the outer downstream surface (46.1) having a first cylindrical surface (46.11) disposed at a first radial position (R1) and a second cylindrical surface (46.12) disposed at a second radial position (R2) different from the first radial position (R1). An outer central lip (44) is disposed between the outer upstream surface (32.1) and the outer downstream surface (46.1), the outer central lip (44) extending circumferentially from the first circumferential end (37) to the second circumferential end (39); and The truncated cone-shaped inner surface (56) extends away from the longitudinal axis (A) at the downstream end of the inner ring sector (30).

2. The seal according to claim 1, characterized in that, The outer upstream surface (32.1) has an axial length (L32) that accounts for 40 to 45% of the total axial length (L) of the inner ring sector (30), and the outer downstream surface (46.1) has an axial length (L46) that accounts for 50 to 70% of the total axial length (L) of the inner ring sector (30).

3. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The wall (48) at one circumferential end (39) and the base (64) for connecting the return member (62) to the inner ring sector (30) define the outer downstream surface (46.1) in the circumferential direction.

4. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The inner ring sector (30) includes an upstream lip (42) protruding upstream toward the longitudinal axis (A) and an inner central lip (58) protruding radially toward the longitudinal axis (A), the upstream lip (42) and the inner central lip (58) each having a distal end (42.1, 58.1) arranged at corresponding radii (R3, R4), the radius (R3) of the distal end (42.1) of the upstream lip (42) being larger than the radius (R4) of the distal end (58.1) of the inner central lip (58).

5. The seal (10, 12, 14) according to claim 4, characterized in that, A first cavity (53) is formed between the upstream lip (42) and the inner central lip (58), and the axial length (L53) of the first cavity (53) accounts for 40 to 70% of the total axial length (L) of the inner ring sector (30).

6. The seal (10, 12, 14) according to claim 5, characterized in that, The first thickness (E32) is defined by the distance between the outer upstream surface (32.1) and the first cavity (53), and the second thickness (E46) is defined by the distance between the first cylindrical surface (46.11) and the first cavity (53), and the second thickness (E46) is preferably at least 50% smaller than the first thickness (E32).

7. The seal (10, 12, 14) according to any one of claims 4 to 6, characterized in that, The distal end (42.1) of the upstream lip (42) has a chamfer.

8. The seal (10, 12, 14) according to any one of claims 4 to 7, characterized in that, The inner ring sector (30) includes a truncated cone-shaped front surface (32.3) that forms an angle (α) greater than or equal to 90° with the upstream lip (42).

9. The seal (10, 12, 14) according to any one of the preceding claims, characterized in that, The inner ring sector (30) includes a cylindrical inner downstream surface (57) whose axial length (L57) accounts for 15 to 25% of the total axial length (L) of the inner ring sector (30).

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

11. The seal (10, 12, 14) according to claim 10 in conjunction with claim 5, characterized in that, A second cavity (55) is formed axially between the inner central lip (58) and the cylindrical inner downstream surface (57), wherein the distance (E46) between the first cylindrical surface (46.11) and the first cavity (53) is equal to the distance (E46) between the first cylindrical surface (46.11) and the second cavity (55), and is equal to the distance (E46) between the second cylindrical surface (46.12) and the cylindrical inner downstream surface (57).

12. The seal (10, 12, 14) according to any one of the preceding claims further includes a secondary seal (59) arranged radially between the inner ring sector (30) and the outer ring sector (60) and located upstream of the return member (62), the secondary seal (59) abutting against the outer center lip (44).

13. A turbine engine (1), comprising: High-pressure compressor (4); Combustion chamber (5); High-pressure turbine (6); The 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 channel (11) separated from the inlet (9) by a first seal (10), a chamber (13) separated from the channel (11) by a second seal (12), an air injector (15) for introducing air into the chamber (13), a vent outlet (20) separated from the chamber (13) by a third seal (14), and an air outlet (19) for directing airflow (18) from the chamber (13) 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 12.

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