Seal for a turbine engine

Abstract

The present disclosure relates to a seal assembly (10), comprising: - a rotor (30),- an annular seal (20), the annular seal (20) comprising a radially inner surface (S1) radially facing the radially outer surface (S2) of the rotor, the radially inner surface (S1) of the annular seal (20) comprising a longitudinal annular portion with limited radial contact (S11) defining a first radial clearance (J1) between the longitudinal annular portion with limited radial contact (S11) and the radially outer surface (S2) of the radially facing rotor, characterised in that the radially inner surface (S1) comprises at least one longitudinal portion with preferential radial contact (S12) defining a second radial clearance (J2) between the at least one longitudinal portion with preferential radial contact (S12) and the radially outer surface (S2) of the radially facing rotor, the second radial clearance (J2) being less than the first radial clearance (J1).

Description

Description Title: Sealing gasket for turbomachine technical field

[0001] This disclosure relates to a seal, and in particular a seal for an aeronautical turbomachine. Previous technique

[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 different countries. 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 result in moderate environmental consequences, with the aim of improving aircraft energy efficiency.

[0004] In this context, engine efficiency is constantly being improved, which sometimes impacts the temperature of the exhaust gases or structural elements downstream of the combustion chamber. Controlling turbine temperatures is crucial for mechanical strength and managing expansion deformations. To this end, the use of ventilation systems is a well-established practice.

[0005] In general, the design of ventilation systems for an aircraft turbomachine is complex and represents a potential loss of performance. To ensure that the ventilation systems are not supplied with more cooling air than necessary, and thus do not unduly impair the turbomachine's performance, labyrinth seals are typically installed at the air intake points between the rotor and the stator. These seals ensure controlled airflow at the locations where they are installed.

[0006] It is common to use labyrinth seals with opposing blades that interact with an abradable element having a honeycomb structure. However, this type of seal has a major drawback: wear caused by friction between the blades and the abradable element. This leads to increased clearance and therefore air leakage through the seal. Such an increase in air leakage causes a rise in air temperature and a decrease in turbomachine efficiency.

[0007] To ensure consistent flow rates through the seals throughout their service life, a hydrodynamic type annular seal was developed. In a nominal operating configuration where the rotor is rotating, this type of seal operates with a controlled and small annular clearance between the seal and the rotor, typically less than 0.2 mm. This clearance is created by the rotor's rotation, which generates a repulsive force between the two parts.

[0008] However, when stationary and at low rotational speeds, before the repulsion effect begins, the seal and the rotor are in contact, which influences wear and degradation of the seal surface. This is especially important when the seal's surface facing the rotor is aerodynamically engineered, for example, with hollow patterns to improve performance. These hollow patterns can gradually wear away due to repeated contact between the rotor and the seal, thus reducing the sealing performance.

[0009] In this context, there is therefore a need for a hydrodynamic type seal that wears less and offers better sealing performance over its lifetime. Summary

[0010] This disclosure addresses that need.

[0011] A sealing assembly is proposed comprising a rotor and a longitudinal axis annular seal. The annular seal surrounds the rotor and is configured to seal against a radially external surface of the rotor. The annular seal includes a radially internal surface facing the radially external surface of the rotor. This radially internal surface of the annular seal includes a longitudinal annular portion with limited radial contact, defining a first radial clearance, which extends annularially between this longitudinal annular portion with limited radial contact and the radially external surface of the rotor.The said radially internal surface further includes at least one longitudinal portion with preferential radial contact defining a second radial clearance, which extends in particular in an annular manner, between said at least one longitudinal portion with preferential radial contact and said radially external surface of the rotor facing radially, the second radial clearance being less than the first radial clearance.

[0012] The first radial set and the second radial set each correspond to a radial set relative to the longitudinal axis of the annular sealing joint.

[0013] In particular, the first radial clearance corresponds to the operating clearance of the annular seal under nominal operating conditions, that is, when the rotor is rotating at its nominal speed. Nominal operating conditions are defined as operating conditions during which the annular seal is free from the radially external surface of the rotor. In other words, under nominal operating conditions, the first radial clearance is non-zero.

[0014] More specifically, the annular sealing ring is of the hydrodynamic type. Such a hydrodynamic ring operates with a predefined operating clearance, also referred to as the "target clearance," between the longitudinal annular portion with limited radial contact on the radially internal surface of the ring and the radially external surface of the opposing rotor. This operating clearance is small, typically less than 0.2 mm. The clearance between the ring and the rotor then varies slightly around the predefined operating clearance value under the ring's operating conditions. When the ring is in its equilibrium position, the operating clearance ensures that the airflow through the ring is the desired airflow. However, if the clearance increases or decreases, the ring will be returned to the operating clearance by a radial displacement of the radially internal surface of the ring.More specifically, if the joint clearance becomes less than the operating clearance, the radial pressure under the radially internal surface of the joint induces a displacement of the latter so as to increase the clearance, while if the joint clearance becomes greater than the operating clearance, a system can exert a force greater than the pressure exerted radially under the radially internal surface of the joint so as to bring said surface back to its equilibrium position.

[0015] The use of this type of seal offers the advantage of controlling leakage at the sealing point, thus improving the turbomachine's performance. It is clear that the seal's tightness is not absolute, meaning that air could not pass through it completely, but rather a relative tightness. The seal's purpose is to allow a controlled amount of air to pass through, but only between the seal and the rotor.

[0016] This mechanical-aerodynamic balance, which regulates a predefined operating clearance, also limits the contact between the rotor and the seal, thus avoiding the wear problem encountered with conventional labyrinth seals.

[0017] Furthermore, the implementation of the second radial clearance, lower than the first radial clearance, allows for a portion—here referred to as the longitudinal portion with preferential radial contact—that is closer radially to the outer radial surface of the rotor. This closer contact is therefore favored in the event of contact between the seal and the rotor, particularly at low rotational speeds, i.e., at a rotational speed of approximately 5% of the rotor's nominal rotational speed. In other words, before the repulsion effect begins, the annular seal and the rotor can preferentially make contact at the longitudinal portion with preferential radial contact on the inner radial surface of the annular seal, thus protecting the longitudinal annular portion with limited radial contact on the inner radial surface of the annular seal.The longitudinal annular portion with limited radial contact, which defines the operating clearance (corresponding to the first radial clearance) of the annular seal, is thus protected from any wear or degradation by contact with the rotor. The sealing assembly as disclosed herein therefore improves wear resistance and thus the performance and service life of the annular seal, and more generally, improves the performance of the turbomachine.

[0018] The longitudinal annular portion with limited radial contact on the radially internal surface of the annular sealing ring may, in particular, have a shape complementary to the radially external surface of the rotor facing radially. The initial radial clearance remains constant between these two surfaces.

[0019] In particular, the longitudinal annular portion with limited radial contact of the radially internal surface of the annular sealing gasket may have a cylindrical shape.

[0020] The longitudinal portion with preferential radial contact on the radially internal surface of the annular sealing ring may, in particular, have a shape complementary to the radially external surface of the rotor opposite it. The second radial clearance remains constant between these two surfaces.

[0021] The longitudinal portion with preferential radial contact is advantageously annular.

[0022] In particular, the longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing gasket may have a cylindrical shape.

[0023] The initial radial clearance can advantageously be between 0.05 mm and 0.20 mm, preferably between 0.10 mm and 0.15 mm. These clearance values ​​ensure sufficient sealing at the gasket while reducing the risk of contact between the gasket and the rotor.

[0024] The ratio between the second radial clearance and the first radial clearance is preferably less than 0.8. This characteristic allows for a sufficient gap between the first radial clearance and the second radial clearance to avoid contact between the longitudinal annular portion with limited radial contact of the radially internal surface of the annular sealing ring and the rotor, while limiting the frequency of contact between the longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing ring and the rotor.

[0025] In one embodiment, at least one longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing gasket projects radially inward relative to the longitudinal annular portion with limited radial contact of the radially internal surface of the annular sealing gasket. This projection allows for the implementation of the clearance gap between the first radial clearance and the second radial clearance.

[0026] In particular, at least one longitudinal portion with preferential radial contact of the radially internal surface of the sealing ring extends radially inward relative to the longitudinal annular portion with limited radial contact of the radially internal surface of the sealing ring by a radial distance corresponding to the difference between the first and second radial clearances. In this configuration, the clearance gap is entirely borne by the sealing ring, which is easier to machine.

[0027] It should be noted that the longitudinal portion with preferential radial contact is defined as the part of the radially internal surface of the annular sealing joint that defines the second radial clearance.

[0028] Therefore, the annular sealing ring may have a protruding and a non-protruding portion that do not, as such, delineate the internal radial surface of the ring into the longitudinal annular portion with limited radial contact and the longitudinal portion with preferential radial contact. In other words, at the protruding portion of the ring, the internal radial surface may include a portion of the longitudinal annular portion with limited radial contact (because it is at a radial distance from the rotor equivalent to the first radial clearance) and at least a portion of the longitudinal portion with preferential radial contact (because it is at a radial distance from the rotor equivalent to the second radial clearance).

[0029] Advantageously, the radially internal surface of the annular sealing ring extends longitudinally over a first length, and at least one longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing ring extends longitudinally over a second length, the ratio of the second length to the first length being between 0.05 and 0.1. As explained previously, the longitudinal portion with preferential radial contact is defined as the part of the radially internal surface of the annular sealing ring that defines the second radial clearance. The second length therefore corresponds to the length over which the second radial clearance extends along the longitudinal axis.The above length value range advantageously allows for a sufficient surface area of ​​at least one longitudinal portion with preferential radial contact to limit the contacts between the seal and the rotor while maintaining good seal performance.

[0030] It should be noted that when at least one longitudinal portion with preferential radial contact comprises two or more longitudinal portions with preferential radial contact, the second length is understood to be the sum of the lengths of each of said longitudinal portions with preferential radial contact.

[0031] In one embodiment, the radially external surface of the rotor includes a longitudinal annular portion with limited radial contact such that the first radial clearance is defined between said longitudinal annular portion with limited radial contact of the radially external surface of the rotor and the longitudinal annular portion with limited radial contact of the radially internal surface of the annular sealing ring. The radially external surface of the rotor further includes a longitudinal annular portion with preferential radial contact such that the second radial clearance is defined between said longitudinal annular portion with preferential radial contact of the radially external surface of the rotor and the longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing ring.The longitudinal annular portion with preferential radial contact on the radially external surface of the rotor advantageously projects radially outwards relative to the longitudinal annular portion with limited radial contact on the radially external surface of the rotor, specifically by a radial distance corresponding to the difference between the first and second radial clearances. In this configuration, the clearance gap is entirely borne by the rotor.

[0032] Furthermore, at least one longitudinal portion with preferential radial contact on the radially internal surface of the annular sealing ring can advantageously extend to one longitudinal end of the sealing ring. Indeed, during rotation, the annular sealing ring can take on a convex shape towards the middle of the seal along its longitudinal axis. Implementing the longitudinal portion with preferential radial contact at one longitudinal end of the seal promotes seal / rotor contact at the level of the longitudinal portion with preferential radial contact.

[0033] According to one embodiment, the radially internal surface of the annular sealing joint may include a single longitudinal portion with preferential radial contact arranged at a longitudinal end of the annular sealing joint, for example at an upstream end or at a downstream end of the annular sealing joint.

[0034] In one embodiment, the radially internal surface of the annular sealing ring may advantageously comprise two longitudinal portions with preferential radial contact, each longitudinal portion extending from one of the two opposite longitudinal ends of the annular sealing ring. This configuration advantageously promotes seal / rotor contact at the longitudinal portions with preferential radial contact, particularly when the rotor is convex towards the middle along its longitudinal axis during operation.

[0035] Furthermore, the annular seal may include hollow patterns opening onto the longitudinal annular portion with limited radial contact on the radially internal surface of the seal. These patterns further improve the mechano-aerodynamic behavior of the annular seal and thus its wear resistance. In this configuration, the implementation of the longitudinal portion with preferential radial contact, defining the second radial clearance, limits the contact between the seal and the rotor at the level of the longitudinal annular portion with limited radial contact, thereby protecting the hollow patterns from wear. The seal's performance is consequently improved.

[0036] At least one longitudinal portion with preferential radial contact may advantageously have a smooth surface, in other words, a surface free of hollow patterns. Such a surface is preferable from a wear perspective because the contacts between said longitudinal portion with preferential radial contact and the rotor are then planar-to-planar contacts.

[0037] More specifically, the annular sealing gasket may include at least one row of hollow patterns opening onto the longitudinal annular portion with limited radial contact of the radially internal surface of the annular sealing gasket.

[0038] The annular sealing gasket may include one or between two and five rows of hollow patterns.

[0039] Each of the hollow patterns can advantageously extend in a direction having a component along the axis of the annular sealing joint.

[0040] Each row of hollow patterns includes, in particular, a plurality of hollow patterns distributed circumferentially.

[0041] According to one embodiment, the rotor may include hollow patterns, for example at least one row of hollow patterns, opening onto the longitudinal annular portion with limited radial contact of the radially external surface of the rotor.

[0042] In particular, the rotor's hollow patterns are offset longitudinally by one-third of the length relative to the longitudinal portion of the radially internal surface of the annular seal. Advantageously, this third length is greater than or equal to the maximum possible relative displacement between the rotor and the annular seal. This feature prevents contact between the rotor and the seal from damaging the rotor's hollow patterns.

[0043] Advantageously, the annular sealing gasket comprises a plurality of sealing sectors distributed circumferentially around the longitudinal axis.

[0044] The annular sealing gasket can, for example, comprise between eight and twenty sealing sectors.

[0045] The annular sealing gasket is preferably made of a nickel-based alloy material.

[0046] The rotor is preferably made of a nickel-based alloy material.

[0047] Advantageously, the annular sealing ring may have, on the longitudinal portion of its internal radially contacting surface with preferential radial contact, a lower hardness than the hardness of the rotor on the portion of the rotor's external radially contacting surface that is radially opposite said longitudinal portion with preferential radial contact. This characteristic promotes wear of the seal rather than the rotor, thus protecting the rotor.

[0048] More specifically, the rotor may include a coating, for example zirconium oxide, at least on the part of the radially external surface of the rotor that is radially opposite the longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing gasket.

[0049] In addition, the sealing assembly is advantageously configured to allow radial movement of the radially internal surface of the annular sealing gasket.

[0050] The sealing assembly may include at least one, for example one or two, radial retaining elements configured to exert a radially inward restoring force on the annular sealing ring. This radial retaining element may, for example, include a helical spring surrounding the annular sealing ring and located in an annular groove of the sealing ring, the helical spring being configured to exert a radially inward restoring force on the annular sealing ring.

[0051] More specifically, the annular sealing ring may include a first annular groove opening radially outwards upstream of the annular sealing ring and a second annular groove opening radially outwards downstream of the annular sealing ring. The first annular groove is designed to receive a first helical spring configured to exert a radially inward restoring force on the annular sealing ring. The second annular groove is designed to receive a second helical spring configured to exert a radially inward restoring force on the annular sealing ring.

[0052] Advantageously, the sealing assembly further comprises a distributor centered on the longitudinal axis, the distributor having a ring of fixed vanes and a foot at its radially internal end. The annular sealing ring is in linear annular mechanical connection with the distributor foot. This connection allows radial movement of the annular sealing ring and therefore of its radially internal surface, which contributes to establishing the clearance during operation.

[0053] The dispenser is preferably made of a nickel-based alloy material.

[0054] According to another aspect, a turbine is proposed comprising the sealing assembly as previously described, in particular a low pressure turbine or a high pressure turbine.

[0055] According to another aspect, a turbomachine is proposed comprising the turbine as previously described. Brief description of the drawings

[0056] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which:

[0057] [Fig. 1] schematically illustrates an example of an aeronautical turbomachine.

[0058] [Fig. 2] schematically illustrates a partial cross-sectional view (figure 2A) of the sealing assembly according to one embodiment and an enlarged view (figure 2B) of said partial view.

[0059] [Fig. 3] schematically illustrates a partial cross-sectional view (figure 3A) of the sealing assembly according to another embodiment and an enlarged view (figure 3B) of said partial view.

[0060] [Fig. 4] schematically illustrates a partial cross-sectional view of the sealing assembly according to another embodiment.

[0061] [Fig. 5] schematically illustrates a partial cross-sectional view of the sealing assembly according to another embodiment.

[0062] [Fig. 6] and [Fig. 7] schematically illustrate two partial views of an annular sealing joint according to one embodiment. Description of the implementation methods

[0063] The figures schematically depict various aspects of the invention. Dimensions are not shown to scale; some dimensions are enlarged to facilitate reading the drawings and understanding the phenomena involved.

[0064] The present invention falls preferably within the field of turbomachinery for aircraft. As such, Figure 1 schematically represents, in cross-section along a vertical plane passing through its longitudinal axis X1, a turbofan engine 1.

[0065] The turbomachine 1 comprises, from upstream AM to downstream AV according to the direction of gas flow within the turbomachine 1, a blower 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, a low-pressure turbine 7 and an exhaust system downstream of the turbomachine 1.

[0066] The gas flow, including air, entering upstream of the turbomachine 1 first circulates through the blower 2 and then divides, on the one hand, into an annular circulation channel called the primary channel 8, and on the other hand, into an annular circulation channel called the secondary channel 9 surrounding the primary channel 8. The low pressure compressor 3, the high pressure compressor 4, the combustion chamber 5, the high pressure turbine 6 and the low pressure turbine 7 are located in the primary channel 8.

[0067] This disclosure relates to a sealing assembly intended for use in a turbomachine turbine as previously described, in particular the low pressure turbine 7 or the high pressure turbine 6.

[0068] With reference to Figures 2A, 2B, 3A and 3B of this disclosure, the assembly 10 comprises a rotor 30 and an annular sealing ring 20 with longitudinal axis X2. The annular sealing ring 20 surrounds the rotor 30 and is configured to cooperate in non-contact sealing with a radially external surface S2 of the rotor 30 in radial opposition.

[0069] The annular sealing ring 20 comprises a radially internal surface S1 facing radially from the radially external surface S2 of the rotor. The radially internal surface S1 of the annular sealing ring 20 comprises a longitudinal annular portion with limited radial contact S11 defining a first radial clearance J1, which extends, in particular, annularly between the longitudinal annular portion with limited radial contact S11 and the radially external surface S2 of the rotor facing radially. The radially internal surface S1 further comprises at least one longitudinal portion with preferential radial contact S12 defining a second radial clearance J2, which extends, in particular, annularly between the at least one longitudinal portion with preferential radial contact S12 and the radially external surface S2 of the rotor facing radially. The second radial clearance J2 is less than the first radial clearance J1.

[0070] In this document, the terms "longitudinal," "radial," and "circumferential" are defined with respect to the longitudinal axis X2 of the annular sealing ring. The terms "inner" and "outer," as well as "internal" and "external," are then defined in the radial direction with respect to the longitudinal axis X2. The longitudinal axis X2 of the annular sealing ring can, in particular, coincide with the longitudinal axis X1 of the turbomachine 1.

[0071] In addition, the sealing assembly is advantageously configured to allow radial movement of the radially internal surface of the annular sealing gasket.

[0072] The sealing assembly may include at least one, for example one or two, radial retaining elements 60 configured to exert a radially inward restoring force on the annular sealing ring. This radial retaining element may, for example, include a helical spring surrounding the annular sealing ring and mounted in an annular groove of the annular sealing ring, this helical spring being configured to exert a radially inward restoring force on the annular sealing ring.

[0073] The sealing assembly 10 may further include a distributor 40 centered on the longitudinal axis X2, the distributor having a ring of fixed vanes and a foot at the radially internal end of the distributor, the annular sealing gasket 20 being in annular linear mechanical connection 50 with the foot of the distributor 40. This connection allows a radial movement of the annular sealing gasket 20 and therefore of its radially internal surface S1 which contributes to the establishment of the clearance in operation.

[0074] The annular sealing ring 20 is preferably made of a nickel-based alloy material. Similarly, the rotor 30 and the distributor 40 can be made of a nickel-based alloy material.

[0075] Advantageously, the annular sealing ring 20 can have, on the longitudinal portion with preferential radial contact S12 of its internal radial surface, a lower hardness than the hardness of the rotor on the portion of the external radial surface of the rotor that is radially opposite said longitudinal portion with preferential radial contact S12. This characteristic promotes wear of the seal and not of the rotor, thus protecting the rotor.

[0076] More specifically, the rotor 30 may include a coating, for example of zirconium oxide, at least on the part of the radially external surface of the rotor which is radially opposite the longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing gasket.

[0077] The spacing between the rotor and the seal in figures 2A, 2B, 3A and 3B is intentionally exaggerated to facilitate identification of the first radial set J1 and the second radial set J2.

[0078] The first radial set J1 and the second radial set J2 each correspond to a radial set with respect to the longitudinal axis X2 of the annular sealing joint 20.

[0079] In particular, the first radial clearance J1 corresponds to the operating clearance of the annular seal during nominal operation, that is, when the rotor is rotating at its nominal speed. Nominal operation is defined as an operating regime during which the annular seal is free from the radially external surface of the rotor. In other words, during nominal operation, the first radial clearance is non-zero.

[0080] More specifically, the annular sealing ring is of the hydrodynamic type. Such a hydrodynamic ring operates with a predefined operating clearance, also referred to as the "target clearance," between the longitudinal annular portion with limited radial contact on the radially inner surface of the ring and the radially outer surface of the opposing rotor. This operating clearance is small, typically less than 0.2 mm. The clearance between the ring and the rotor then varies slightly around the predefined operating clearance value under the ring's operating conditions. When the ring is in its equilibrium position, the operating clearance ensures that the airflow through the ring is the desired airflow.

[0081] However, if the clearance increases or decreases, the seal will be returned to its operating clearance by a radial displacement of the radially internal surface of the seal. More precisely, if the seal clearance becomes less than the operating clearance, the radial pressure under the radially internal surface of the seal induces a displacement of this surface such as to increase the clearance, while if the seal clearance becomes greater than the operating clearance, at least one radial retaining element exerts a restoring force greater than the pressure exerted radially under the radially internal surface of the seal so as to return said surface to its equilibrium position.

[0082] The use of this type of seal offers the advantage of controlling leakage at the sealing point, thus improving the turbomachine's performance. It is clear that the seal's tightness is not absolute, meaning that air could not pass through it completely, but rather a relative tightness. The seal's purpose is to allow a controlled amount of air to pass through, but only between the seal and the rotor.

[0083] This mechanical-aerodynamic balance, which regulates a predefined operating clearance, also limits the contact between the rotor and the seal, thus avoiding the wear problem encountered with conventional labyrinth seals.

[0084] Furthermore, the implementation of the second radial clearance lower than the first radial clearance allows for the provision of a portion, here referred to as the longitudinal portion with preferential radial contact, which is closer radially to the radially external surface of the rotor and which is therefore favored in the event of contacts between the seal and the rotor, particularly at low rotational speed, i.e. at a rotational speed of the order of 5% of the nominal rotational speed of the rotor.

[0085] In other words, before the repulsion effect begins, the annular seal and the rotor can preferentially make contact at the longitudinal portion with preferential radial contact on the radially internal surface of the annular seal, thus protecting the longitudinal annular portion with limited radial contact on the radially internal surface of the annular seal. The longitudinal annular portion with limited radial contact, which defines the operating clearance (corresponding to the first radial clearance) of the annular seal, is therefore protected from wear or degradation through contact with the rotor. The sealing assembly described in this disclosure consequently improves wear behavior and therefore the performance and service life of the annular seal, and more generally, improves the performance of the turbomachine.

[0086] The longitudinal annular portion with limited radial contact S11 of the radially internal surface S1 of the annular sealing gasket may, in particular, have a shape complementary to the radially external surface S2 of the rotor facing radially. The first radial clearance J1 remains constant between these two surfaces.

[0087] In particular, the longitudinal annular portion with limited radial contact S11 of the radially internal surface of the annular sealing gasket may have a cylindrical shape.

[0088] The longitudinal portion with preferential radial contact S12 of the radially internal surface S1 of the annular sealing ring may, in particular, have a shape complementary to the radially external surface S2 of the rotor facing radially. The second radial clearance J2 remains constant between these two surfaces.

[0089] The longitudinal portion with preferential radial contact S12 is advantageously annular.

[0090] In particular, the longitudinal portion with preferential radial contact S12 of the radially internal surface of the annular sealing gasket may have a cylindrical shape.

[0091] Other shapes are also possible, for example a truncated cone. The important thing is to have complementary surfaces in order to define a second radial clearance J2 that is smaller than the first radial clearance J1.

[0092] The first radial clearance J1 can advantageously be between 0.05mm and 0.20mm, preferably between 0.10mm and 0.15mm. These clearance values ​​ensure sufficient sealing at the gasket while reducing the risk of contact between the gasket and the rotor.

[0093] The ratio between the second radial clearance J2 and the first radial clearance J1 is preferably less than 0.8. This characteristic allows a sufficient gap between the first radial clearance J1 and the second radial clearance J2 to avoid contact between the longitudinal annular portion with limited radial contact S11 of the radially internal surface of the annular sealing ring and the rotor while limiting the frequency of contact between the longitudinal portion with preferential radial contact of the radially internal surface of the annular sealing ring and the rotor.

[0094] It should be noted that the longitudinal portion with preferential radial contact S12 is defined as the part of the radially internal surface S1 of the annular sealing joint which defines the second radial clearance J2.

[0095] Advantageously, the radially internal surface S1 of the annular sealing ring 20 can extend longitudinally over a first length L1, and at least one longitudinal portion with preferential radial contact S12 of the radially internal surface S1 of the annular sealing ring 20 extends longitudinally over a second length L2, the ratio of the second length L2 to the first length L1 being between 0.05 and 0.1. The longitudinal portion with preferential radial contact S12 is defined as the part of the radially internal surface of the annular sealing ring that defines the second radial clearance J2. The second length L2 therefore corresponds to the length over which the second radial clearance J2 extends along the longitudinal axis X2.The above length value range advantageously allows for a sufficient surface area of ​​at least one longitudinal portion with preferential radial contact to limit the contacts between the seal and the rotor while maintaining good seal performance.

[0096] It should be noted that when at least one longitudinal portion with preferential radial contact S12 comprises two or more longitudinal portions with preferential radial contact, the second length L2 is understood to be the sum of the lengths of each of said longitudinal portions with preferential radial contact S12.

[0097] According to an embodiment shown in Figures 2A and 2B, at least one longitudinal portion with preferential radial contact S12 of the radially internal surface S1 of the annular sealing ring 20 extends radially inward relative to the longitudinal annular portion with limited radial contact S11 of the radially internal surface S1 of the annular sealing ring 20, in particular by a radial distance corresponding to the difference between the first radial clearance J1 and the second radial clearance J2. In this configuration, the clearance gap is entirely borne by the annular sealing ring, which is easier to machine.

[0098] As explained previously, the longitudinal portion with preferential radial contact S12 is defined as the part of the radially internal surface S1 of the annular sealing gasket that defines the second radial clearance J2. Therefore, the annular sealing gasket 20 may have a protruding portion 26 and a non-protruding portion 25 which do not, as such, delimit the radially internal surface S1 of the gasket into the longitudinal annular portion with limited radial contact S11 and the longitudinal portion with preferential radial contact S12.In other words, as illustrated in Figures 3A and 3B, at the level of the protruding part 26 of the joint, the radially internal surface S1 can include a part of the longitudinal annular portion with limited radial contact S11 (because at a radial distance from the rotor equivalent to the first radial clearance J1) and at least a part of the longitudinal portion with preferential radial contact S12 (because at a radial distance from the rotor equivalent to the second radial clearance J2).

[0099] According to another embodiment shown in Figures 3A and 3B, the radially external surface S2 of the rotor 30 includes a longitudinal annular portion with limited radial contact S21 such that the first radial clearance J1 is defined between said longitudinal annular portion with limited radial contact S21 of the radially external surface S2 of the rotor 30 and the longitudinal annular portion with limited radial contact S11 of the radially internal surface S1 of the annular sealing joint 20.

[0100] The radially external surface S2 of the rotor 30 further includes a longitudinal annular portion with preferential radial contact S22 such that the second radial clearance J2 is defined between said longitudinal annular portion with preferential radial contact S22 of the radially external surface S2 of the rotor 30 and the longitudinal portion with preferential radial contact S12 of the radially internal surface S1 of the annular sealing joint 20.

[0101] The longitudinal annular portion with preferential radial contact S22 of the radially external surface S2 of the rotor 30 extends radially outwards relative to the longitudinal annular portion with limited radial contact S21 of the radially external surface S2 of the rotor 30, in particular by a radial distance corresponding to the difference between the first radial clearance J1 and the second radial clearance J2. In this configuration, the clearance gap is entirely borne by the rotor.

[0102] It is also possible to implement protruding parts on the annular sealing joint and on the rotor, the important thing being to define between the surfaces the first radial clearance J1 and the second radial clearance J2.

[0103] Furthermore, as shown in Figures 2A, 2B, 3A, and 3B, at least one longitudinal portion with preferential radial contact S12 of the radially internal surface S1 of the annular sealing gasket can advantageously extend to one longitudinal end of the annular sealing gasket 20. Indeed, during rotation, the annular sealing gasket can assume a convex shape towards the middle of the gasket along the longitudinal axis. Implementing the longitudinal portion with preferential radial contact at one longitudinal end of the gasket promotes gasket / rotor contact at the level of the longitudinal portion with preferential radial contact S12.

[0104] As illustrated in Figures 2A, 2B, 3A and 3B, the radially internal surface S1 of the annular sealing joint 20 may include a single longitudinal portion with preferential radial contact arranged at a longitudinal end of the annular sealing joint 20, for example at an upstream end or a downstream end of the annular sealing joint.

[0105] As illustrated in Figure 4, the radially internal surface S1 of the annular sealing ring 20 may advantageously comprise two longitudinal portions with preferential radial contact S12, each longitudinal portion with preferential radial contact S12 extending from one of the two opposite longitudinal ends of the annular sealing ring 20. This configuration advantageously promotes seal / rotor contacts at the longitudinal portions with preferential radial contact, particularly when the seal takes on a convex shape towards the middle along the longitudinal axis in operation.

[0106] The annular sealing joint 20 preferably comprises hollow motifs 23 opening onto the longitudinal annular portion with limited radial contact S11 of the radially internal surface of the annular sealing joint.

[0107] The design further improves the aerodynamic behavior of the annular seal and thus its wear resistance. In this configuration, the implementation of the longitudinal portion with preferential radial contact S12, defining the second radial clearance J2, limits contact between the seal and the rotor at the level of the longitudinal annular portion with limited radial contact, thereby protecting the hollow patterns from wear. The seal's performance is consequently improved.

[0108] The longitudinal portion with preferential radial contact S12 may advantageously have a smooth surface, in other words, a surface free of hollow patterns. Such a surface is preferable from a wear perspective because the contacts between said longitudinal portion with preferential radial contact and the rotor are then planar-to-planar contacts.

[0109] With reference to Figure 5, the rotor 30 may include hollow patterns 31, at least one row of hollow patterns, opening onto the longitudinal annular portion with limited radial contact S21 of the radially external surface S2 of the rotor 30.

[0110] In particular, the rotor's hollow patterns are offset longitudinally by one-third of the length relative to the longitudinal portion of the radially inner surface of the annular seal. Advantageously, this third length is greater than or equal to the maximum possible relative displacement between the rotor and the annular seal. This feature prevents contact between the rotor and the seal from damaging the rotor's hollow patterns.

[0111] Figure 6 illustrates in more detail an example of the realization of the annular sealing joint 20 in which the annular sealing joint comprises a plurality of sealing joint sectors 21 distributed circumferentially around the longitudinal axis X2.

[0112] The annular sealing joint 20 can, for example, comprise between eight and twenty sealing joint sectors 21.

[0113] Each sealing sector 21 is specifically configured to fit together with two other circumferentially adjacent sealing sectors, for example by a form cooperation between the circumferential ends of the adjacent sealing sectors.

[0114] The annular sealing ring 20 advantageously includes an annular groove 22 opening radially outside the annular sealing ring, the annular groove 22 being intended to receive the radial retaining element 60 configured to exert a radially inward restoring force on the annular sealing ring. As explained previously, the radial retaining element may include a helical spring.

[0115] More specifically, the annular sealing ring 20 may include a first annular groove 22 opening radially outwards upstream of the annular sealing ring and a second annular groove 22 opening radially outwards downstream of the annular sealing ring. The first annular groove is designed to receive a first helical spring configured to exert a radially inward restoring force on the annular sealing ring. The second annular groove is designed to receive a second helical spring configured to exert a radially inward restoring force on the annular sealing ring.

[0116] Furthermore, with reference to Figure 7, which represents a partial view of the longitudinal annular portion with limited radial contact S11 of the radially internal surface of the annular sealing gasket, the annular sealing gasket 20 comprises at least one, for example one or between two and five, row of hollow motifs 23 opening onto the longitudinal annular portion with limited radial contact S11 of the radially internal surface S1 of the annular sealing gasket 20. The motifs 23 improve the aerodynamic behavior of the annular sealing gasket 20 and thus the wear behavior of said gasket.

[0117] It is understood that the motifs 23 are notably separated by non-hollow portions 24 of the radially internal surface S1.

[0118] Each row of patterns includes, in particular, a plurality of patterns distributed circumferentially. Each row of patterns, for a sealing joint sector, may include more than five patterns, for example between five and twenty patterns, preferably between seven and fifteen patterns, or even between nine and eleven patterns.

[0119] The minimum depth along the radial direction of the patterns can be between 1.5 and 2.5 times the first radial clearance J1 for the annular sealing gasket. These depth values ​​ensure excellent pressure distribution within the gasket, thus improving its efficiency.

[0120] Furthermore, each of the hollow patterns can advantageously extend in a direction having a component along the longitudinal axis of the annular sealing joint.

[0121] In particular, patterns 23 may have a parallelepiped shape.

Claims

Demands

1. Sealing assembly (10) comprising: - a rotor (30), - an annular sealing gasket (20) with a longitudinal axis (X2) surrounding the rotor (30) and configured to cooperate in sealing with a radially external surface (S2) of the rotor (30) facing radially, the annular sealing gasket (20) comprising a radially internal surface (S1) facing radially from said radially external surface (S2) of the rotor, said radially internal surface (S1) of the annular sealing joint (20) comprising a longitudinal annular portion with limited radial contact (S11) defining a first radial clearance (J1) between said longitudinal annular portion with limited radial contact (S11) and said radially external surface (S2) of the rotor facing radially, characterized in that said radially internal surface (S1) comprises at least one longitudinal portion with preferential radial contact (S12) defining a second radial clearance (J2) between at least one longitudinal portion with preferential radial contact (S12) and said radially external surface (S2) of the rotor in radially opposite direction, the second radial set (J2) being smaller than the first radial set (J1), in which the ratio between the second radial set (J2) and the first radial set (J1) is less than 0.

8.

2. Sealing assembly (10) according to claim 1, wherein at least one longitudinal portion with preferential radial contact (S12) of the radially internal surface (S1) of the annular sealing joint (20) extends radially inwardly relative to the longitudinal annular portion with limited radial contact (S11) of the radially internal surface (S1) of the annular sealing joint (20), in particular by a radial distance corresponding to the difference between the first radial clearance (J1) and the second radial clearance (J2).

3. Sealing assembly (10) according to any one of the preceding claims, wherein the radially internal surface (S1) of the annular sealing joint (20) extends longitudinally over a first length (L1) and at least one longitudinal portion with preferential radial contact (S12) of the radially internal surface (S1) of the annular sealing joint (20) extends longitudinally over a second length (L2), the ratio of the second length (L2) to the first length (L1) being between 0.05 and 0.

1.

4. Sealing assembly (10) according to any one of the preceding claims, wherein the radially external surface (S2) of the rotor (30) comprises a longitudinal annular portion with limited radial contact (S21) such that the first radial clearance (J1) is defined between said longitudinal annular portion with limited radial contact (S21) of the radially external surface (S2) of the rotor (30) and the longitudinal annular portion with limited radial contact (S11) of the radially internal surface (S1) of the annular sealing joint (20),the radially external surface (S2) of the rotor (30) further comprising a longitudinal annular portion with preferential radial contact (S22) such that the second radial clearance (J2) is defined between the longitudinal annular portion with preferential radial contact (S22) of the radially external surface (S2) of the rotor (30) and the longitudinal portion with preferential radial contact (S12) of the radially internal surface (S1) of the annular sealing joint (20), the longitudinal annular portion with preferential radial contact (S22) of the radially external surface (S2) of the rotor (30) extending radially outwards relative to the longitudinal annular portion with limited radial contact (S21) of the radially external surface (S2) of the rotor (30), in particular by a radial distance corresponding to the difference between the first radial clearance (J1) and the second radial clearance (J2).

5. Sealing assembly (10) according to any one of the preceding claims, wherein one of at least one longitudinal portion with preferential radial contact (S12) extends to a longitudinal end of the annular sealing joint (20).

6. Sealing assembly (10) according to any one of the preceding claims, wherein the radially internal surface (S1) of the annular sealing joint (20) comprises two longitudinal portions with preferential radial contact (S12), each longitudinal portion with preferential radial contact (S12) extending from one of the two opposite longitudinal ends of the annular sealing joint (20).

7. Sealing assembly (10) according to any one of the preceding claims, wherein the annular sealing gasket (20) comprises at least one row of hollow patterns (23) opening onto the longitudinal annular portion with limited radial contact (S11) of the radially internal surface (S1) of the annular sealing gasket (20).

8. Sealing assembly (10) according to any one of the preceding claims, wherein the rotor (30) comprises at least one row of hollow patterns (31) opening onto the longitudinal annular portion with limited radial contact (S21) of the radially external surface (S2) of the rotor (30).

9. Sealing assembly (10) according to any one of the preceding claims, comprising at least one radial retaining element (60) configured to exert a radially inward restoring force on the annular sealing gasket (20).

10. Sealing assembly (10) according to the preceding claim, wherein the radial retaining element (60) comprises a helical spring which surrounds the annular sealing gasket and which is mounted in an annular groove (22) of the annular sealing gasket, the helical spring being configured to exert a radially inward restoring force on the annular sealing gasket.

11. Sealing assembly (10) according to the preceding claim, wherein the annular sealing gasket (20) comprises a first annular groove (22) opening radially outwards upstream of the annular sealing gasket and a second annular groove (22) opening radially outwards downstream of the annular sealing gasket, the first annular groove being intended to receive a first helical spring configured to exert a restoring force radially inwards on the annular sealing gasket, the second annular groove being intended to receive a second helical spring configured to exert a restoring force radially inwards on the annular sealing gasket.

12. Sealing assembly (10) according to any one of the preceding claims, further comprising a distributor (40) centered on the longitudinal axis (X2), the distributor having a ring of fixed vanes and a foot at the radially internal end of the distributor, the annular sealing joint (20) being in annular linear mechanical connection (50) with the foot of the distributor (40).

13. Turbine (6,7) comprising the sealing assembly (10) according to any one of the preceding claims.

14. Turbomachine (1) comprising a turbine according to the preceding claim.

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