Architecture for a turbomachine gasket

Abstract

The invention relates to a gasket configured to ensure a predefined clearance (j) between the gasket and an outer surface (500) and comprising a plurality of gasket sectors distributed circumferentially around the axis A, each gasket sector comprising an inner ring sector (13) connected to an outer ring sector (11) by a return member (12), the gasket being characterised in that the radially inner surface (Sint) of each inner ring sector comprises at least one pattern (31, 32) hollowed out from the radially inner surface of the inner ring sectors, the inner ring sector further comprising at least one channel (501) connecting a first opening (502) which opens onto the upstream face of the inner ring sector and a second opening (503) which opens into one of the patterns hollowed out from the radially inner surface of the inner ring sectors.

Description

Description Title of the invention: Architecture for a turbomachine seal Technical Field

[0001] This presentation concerns sealing devices for aeronautical turbomachines and more specifically the architectures of such devices. Prior art

[0002] The design of the ventilation circuits of an aeronautical turbomachine is delicate and represents a potential loss of performance.

[0003] Indeed, the turbomachine is all the more efficient when it operates at high temperatures. However, the materials it is made of then require more significant cooling. Cooling is generally achieved by taking part of the air from the cold air stream, which is detrimental to overall performance.

[0004] In addition, the cooling circuit requires a complex architecture to allow the cooling air to reach the blades to be cooled from the point where it is taken.

[0005] To ensure that the air circuit is not supplied with more cooling air than necessary, and therefore does not unduly impair the performance of the turbomachine, labyrinth seals are generally fitted at the air intake points.

[0006] Such seals ensure controlled airflow at the locations where they are installed. The classic architecture of labyrinth seals includes lips arranged opposite abradable elements that have a honeycomb-type alveolar structure.

[0007] This type of seal, however, has the disadvantage that the wear of the wipers by friction against the abradable elements increases the clearance of the seal over the life of the seal, and thus allows a greater passage of air, which ultimately leads to too much air being drawn in and therefore to a loss of performance of the turbomachine.

[0008] Alternatives to such labyrinth seals are sometimes offered.

[0009] For example, self-adaptive seals, sometimes called hydrostatic, are proposed in the literature.

[0010] Such seals propose to form a seal by arranging a main surface of the seal which includes patterns facing another surface, rotating relative to the main surface and separated therefrom by a predefined clearance.

[0011] It is understood that the sealing involved here is not a strict sealing in the sense that air could not pass through the seal, but a relative sealing, the purpose of the seal being to allow a defined quantity of air to pass through, quantified by the predefined clearance.

[0012] The seal is said to be self-adaptive because the surface comprising the patterns interacts with the incident air flow in such a way that: - if the clearance decreases, the air pressure between the seal surface and the facing surface increases, so as to push the seal back and thus bring it back to the predefined clearance; and - if the clearance increases, the air pressure between the surface of the seal and the facing surface decreases, so that a return element connected to the seal allows the seal to be returned to the predefined clearance.

[0013] It should be noted, however, that the use of such seals is currently limited by the fact that contact between the main surface of the seal and the facing surface must be avoided under all circumstances, and in particular even in unusual, borderline or accidental behavior.

[0014] Current operation therefore does not allow for the production of self-adapting seals that allow a clearance smaller than half a millimeter, while self-adapting seals are an enviable alternative to labyrinth seals, and this is why there remains a need for such seals that could be used with a clearance smaller than current self-adapting seals.

[0015] Indeed, the behavior of such a self-adapting seal, in particular its displacement, is conditioned by the pressure difference between the upstream and downstream of the seal.

[0016] However, in certain idle operating regimes of the turbomachine, particularly during the approach before landing, the pressure difference between upstream and downstream of the seal can be relatively low.

[0017] In addition, landing can cause significant unbalance on the rotor shaft, thus significant displacement of the surface opposite the seal.

[0018] In the presence of a low pressure difference between upstream and downstream combined with a significant displacement of the surface facing the seal, it is possible that the internal surface of the seal is not reactive enough to avoid coming into contact with the facing surface.

[0019] Contact between the inner surface of the gasket and the facing surface of the gasket may damage the gasket, requiring premature replacement.

[0020] This unusual behavior must nevertheless be planned for in the dimensioning of the seal and this is why it remains necessary to improve the behavior of the sealing gasket in order to be able to reduce the play. Statement of the invention

[0021] The invention aims precisely to meet this need. To this end, it proposes a new architecture for a self-adapting seal to improve its responsiveness, particularly when the pressure difference between the upstream and downstream sides of the seal is relatively low.

[0022] The invention relates, according to a first of its aspects, to a seal configured to ensure a predefined clearance between said seal and an external surface of a rotor rotatably mounted around an axis A and arranged opposite the seal, the axis A defining an axial direction, the seal extending circumferentially around the axis A and comprising a plurality of seal sectors distributed circumferentially around the axis A, each seal sector comprising, radially with respect to the axis A, an inner ring sector connected to an outer ring sector by a return member, the seal being characterized in that the radially inner surface of each inner ring sector comprises at least one pattern hollowed out from the radially inner surface of the inner ring sectors,the inner ring sector further comprising at least one channel connecting a first opening which opens onto the upstream face of the inner ring sector and a second opening which opens into one of the patterns hollowed out from the radially inner surface of the inner ring sectors.,

[0023] Such a seal architecture differs radically from a labyrinth seal.

[0024] However, the internal surface of the internal ring sector does ensure aerodynamic sealing by ensuring a predefined clearance with the facing surface.

[0025] In addition, the presence of the channel ensures an air supply directly under the internal surface of the internal ring sector of the seal. This additional air creates a strong local overpressure at the level of at least one pattern, making it possible to increase the responsiveness of the seal.

[0026] In particular, the presence of the channel makes it possible to ensure a pressure applied to the internal ring sector at least 30% higher than that of an identical seal but without the channel.

[0027] Since the reactivity of the seal is correlated to the pressure applied radially under the internal surface of the internal ring sector, this overpressure does indeed cause greater reactivity of the seal.

[0028] In addition, the presence of the channel makes it possible to lighten the entire device by approximately 10%. This weight saving is beneficial for the desired aeronautical application, but also because it causes an increase in the natural frequency of the seal, which reduces the risk of resonance phenomena occurring when using such a seal.

[0029] In one embodiment, axis A may be the main axis of a turbomachine.

[0030] In one embodiment, the radially inner surface of each inner ring sector comprises a plurality of patterns repeated in the circumferential direction, and these patterns will be referred to as a pattern row.

[0031] In one embodiment, each of the patterns has an elongated shape extending in a direction oblique to the axial direction and being separated from another pattern by an unhollowed portion of the internal surface.

[0032] In one embodiment, the radially inner surface of each inner ring sector comprises at least two rows of patterns, each of the patterns having an elongated shape extending in a direction oblique to the axial direction and being separated from another pattern by an unhollowed portion of the inner surface.

[0033] The "circumferential distribution" of the joint sectors is intended to mean that each joint sector defines a portion of the circumference of the joint, and that the set of joint sectors makes it possible to obtain the complete joint.

[0034] In one embodiment, the circumferential distribution is regular, and each seal sector then represents an equal portion of the circumference of the seal.

[0035] It is understood that the predefined clearance is a "target" clearance, and that it is possible for the clearance to vary slightly around the predefined clearance value under conditions of use of the seal. When the seal is in its equilibrium position, the predefined clearance ensures that the airflow through the seal is the desired airflow. However, if the clearance increases or decreases, the entire seal will be returned to the predefined clearance by the spring behavior of the internal ring sectors provided by the return members or by the overpressure which then appears under the internal surface of the seal.

[0036] Generally, the patterns present in the thickness of the internal surface of the internal ring sector make it possible to improve the aerodynamic behavior of the seal.

[0037] The patterns carved from the inner surface of the inner ring sector also allow the seal behavior to be modified, in particular by further increasing the pressure exerted by the air on the inner surface of the inner ring sector when the latter approaches the facing surface.

[0038] This makes contact between the inner surface of the inner ring sector and the radially facing surface even more unlikely, thus reducing the risk of seal wear.

[0039] The patterns are said to be "carved from the inner surface of the inner ring sector" because it must be understood that the patterns form a relief in the radial direction of the ring sector, i.e. the direction perpendicular to the axis A, and from the inner surface of the inner ring sector.

[0040] The patterns have elongated shapes, for example parallelepipeds. It is thus understood that the depth profile of the internal surface of the internal ring sector defining a pattern is identical in the circumferential direction over a given distance which will be arbitrarily called the width of the pattern.

[0041] The second dimension of the pattern, in the plane of the inner surface of the inner ring sector will be arbitrarily called length.

[0042] It is not outside the scope of the invention if the width is greater than the length but, for the sake of simplicity, we will only describe cases in which a pattern is longer than it is wide.

[0043] The dimensions are characterized by width and length for simplicity, but the invention is not limited to the case where the patterns are rectangular and it concerns long, and more precisely parallelepiped, patterns.

[0044] Thus, and as described, the length of a pattern is in an oblique direction relative to the axial direction.

[0045] The inclination quantifying the "oblique" characteristic of the patterns is understood as the angle defined between the direction in which the length of a pattern extends and the axial direction.

[0046] In one embodiment, the angle of inclination of each pattern relative to the axial direction may be greater than or equal to 30°.

[0047] The angle of inclination of the patterns allows on the one hand to inscribe more patterns or patterns of greater length on the surface of an internal ring sector of given dimensions.

[0048] In one embodiment, the angle of inclination of the patterns is between 30° and 60°, or even between 30° and 45°.

[0049] In fact, this also ensures that the air flow, which may have a tangential speed due to the rotation of several elements with which it may be in contact, enters the pattern without seeing too great a discontinuity.

[0050] Preferably, the angle of inclination is oriented in the same direction as the tangential velocity of the air flow, or in the direction of rotation of the facing surface relative to the internal ring sector.

[0051] The surface facing the seal is a surface of a rotor rotatably mounted about the axis A, for example the rotor of a high-pressure turbine of an aeronautical turbomachine. In one embodiment, the patterns may be inclined in the same direction as the direction of rotation of the rotor.

[0052] This ensures that the orientation of the patterns is in the direction of the tangential velocity of the air passing through said patterns, which improves the overall performance of the seal.

[0053] As described, the inner ring sector comprises at least one channel connecting a first opening disposed on the upstream face of the inner ring and a second opening on the inner face of the inner ring sector, the second opening being arranged in one of the patterns.

[0054] In one embodiment, the radially inner surface of each inner ring sector comprises at least two rows of patterns and the second opening is disposed in a pattern of the second row of patterns.

[0055] In one embodiment, the predefined clearance of the seal may be between 0.1 and 1.0 mm or even between 0.5 mm and 1.0 mm.

[0056] This clearance is much smaller than those accessible for self-adaptive seals of the prior art, but the seal is nevertheless functional thanks to the addition of the channel in particular.

[0057] In one embodiment, the diameter of the channel increases between the first and second openings.

[0058] In one embodiment, the first opening may comprise a diameter greater than or equal to 0.5 mm.

[0059] In one embodiment, the first opening is disposed radially above an unrecessed portion of the radially inner surface of the inner ring sector. In other words, the first opening is disposed radially above a separation between two patterns of the first row of patterns.

[0060] It is understood that the first row of patterns is the first row encountered by the airflow passing the seal.

[0061] Thus, the first row of patterns can also be characterized as the “upstream row”, and the second row as the “downstream row”.

[0062] In one embodiment, a row of patterns may comprise more than five patterns, for example between 5 and 20 patterns, preferably between 7 and 15 patterns, or even between 9 and 11 patterns.

[0063] In one embodiment, a given inner ring sector comprises a plurality of channels. For example, the number of channels per inner ring sector may be greater than or equal to 3. In other words, in one embodiment, several patterns in the second row comprise a second opening, or even all of the patterns have a second opening.

[0064] In one embodiment, all of the present channels open into patterns of the second row of patterns.

[0065] In an embodiment in which the radially inner surface of each inner ring sector comprises at least two rows of patterns, no channel opens into the first row of patterns.

[0066] In an embodiment in which the radially inner surface of each of the inner ring sectors comprises a first and a second row of patterns, and in which each pattern of the second row of patterns is connected to at least one channel connecting a first opening which opens onto the upstream face of the inner ring sector and a second opening which opens into the pattern.

[0067] Indeed, an embodiment with a single channel may be sufficient for the applied overpressure to be sufficient to improve the responsiveness of the seal. However, increasing the number of channels makes it possible to further improve the responsiveness of the seal and to standardize its behavior in the circumferential direction.

[0068] As described, the second opening provides local overpressure radially below the inner surface of the inner ring sector of the seal. This generates a force on the seal surface directed from the rotating surface to the inner surface of the inner ring sector, i.e. it tends to increase the clearance.

[0069] Since this force is applied locally, it can cause the seal to behave inconsistently in its circumferential dimension. To make the seal behave uniformly in the circumferential direction, the number of openings in that direction can be increased.

[0070] In one embodiment, the second opening(s) are arranged symmetrically in the circumferential direction of the seal.

[0071] This then ensures uniform behavior of the seal, or more precisely of the inner ring sector in its circumferential direction.

[0072] In one embodiment, there are as many channels as there are patterns in the second row of patterns, each channel opening into a separate pattern in the second row.

[0073] In one embodiment, the patterns have a planar portion over which the depth does not vary, and the depth of this planar portion will be considered to be the depth of the pattern. If the patterns do not have such a planar portion or if they have more than one flat portion, we will call the depth of the pattern the average depth of the pattern.

[0074] The depth of a pattern is understood as the distance between the inner surface of the undug inner ring sector and the surface of the pattern, measured perpendicular to the surface of the inner ring sector, i.e. in the radial direction.

[0075] The embodiments now described make it possible to ensure a faster return of the seal to its predefined clearance, and therefore to its equilibrium position.

[0076] Furthermore, they ensure that the radially inner surface of the inner ring sector does not come into contact with the facing surface in intended or even accidental operating modes.

[0077] In one embodiment, the patterns in the first row of patterns have a depth greater than or equal to the patterns in the second row of patterns.

[0078] In one embodiment, the radially inner surface of each of the inner ring sectors comprises a first and a second row of patterns, and each pattern of the first row of patterns has a planar downstream zone of constant and non-zero depth and an upstream pattern zone in which the depth varies in a decreasing manner while remaining greater than the constant depth of the downstream pattern zone.

[0079] In this embodiment, the upstream zone ensures low pressure loss at the inlet of the seal. This improves the efficiency of the seal as a whole.

[0080] In one embodiment, the upstream area of ​​each pattern of the first row of patterns may have a rounded, i.e. convex, shape.

[0081] The downstream zone performs the general role of the pattern which is to increase the pressure on the internal surface of the inner ring sector when the clearance is lower than the predefined clearance.

[0082] Furthermore, since two patterns are separated by an unhollowed portion of the inner surface of the inner ring sector and the depth of the downstream portion of the first row pattern is non-zero, this embodiment ensures that air flowing through the first pattern encounters a radially directed wall at the end of the first pattern.

[0083] These walls ensure that the force exerted by the air radially under the internal surface of the internal ring sector is directed in the radial direction, and this independently of its tangential speed.

[0084] In one embodiment, the depth of the downstream portion of the pattern of the first row may be between 1.5 times and 2.5 times the predefined clearance for the seal, for example between 0.1 mm and 1.0 mm.

[0085] The inventors have in fact noted that these depth values ​​ensure excellent pressure distribution in the seal, which improves its efficiency.

[0086] In one embodiment, at least one pattern of the second row of patterns has a planar downstream pattern area of ​​constant, non-zero depth and an upstream pattern area in which the depth of the pattern varies increasingly from the inner surface of the inner ring sector while remaining less than the constant depth of the downstream pattern area.

[0087] This embodiment allows for a new compression of the air entering the pattern, ensuring an additional force under the seal, and therefore better control of the latter in its return to the equilibrium position.

[0088] In one embodiment, the radially inner surface of each of the inner ring sectors comprises a first and a second row of patterns, the patterns of the first row of patterns being offset in the circumferential direction from the patterns of the second row of patterns.

[0089] For example, the patterns in the second row are offset in the circumferential direction relative to the patterns in the first row by a distance between 0.25 times the width of a pattern and 0.75 times the width of a pattern, or even between 0.45 times the width of a pattern and 0.55 times the width of a pattern.

[0090] This embodiment ensures that the air flow passing through the seal and having a tangential speed encounters patterns from both rows of patterns during its passage through the seal.

[0091] In one embodiment, the second openings may open into the upstream portion in which the depth of the pattern varies.

[0092] In one embodiment, the patterns of the second row of patterns that include a second opening may have a geometry different from that described above and / or from the first patterns.

[0093] In particular, in one embodiment, the patterns of the second row in which a second opening is present may have a different geometry than the patterns of the second row not comprising a second opening.

[0094] For example, in one embodiment the patterns of the second row in which a second opening is present may have a constant depth.

[0095] For example, the geometry may have a flared upstream portion, i.e. one whose width increases, between the second opening and the downstream portion, then a downstream portion of constant width.

[0096] For example, the constant width can be the same as the width of the first patterns and / or the width of the other patterns in the second row of patterns.

[0097] In one embodiment, the width of the downstream end of the patterns of the second row of patterns may be greater than or equal to 4 times the diameter of the second opening.

[0098] This embodiment ensures excellent work of the air introduced into the second pattern to increase the responsiveness of the seal.

[0099] In one embodiment, the upstream portion of the patterns of the second row of patterns comprising a second flared opening which can fit into a cone whose angle is between 10° and 45° inclusive.

[0100] It is said that the upstream flared portion can be inscribed in a cone because it is not necessary for the flared portion to be straight provided that its width in the circumferential direction increases.

[0101] This embodiment ensures that the air supplied via the channel directly to the pattern of the second row by the supply channel is properly channeled into this pattern, which ensures a reduction in pressure losses when introducing air via the channel.

[0102] In one embodiment, the channel comprises an elbow forming an angle which may be between 60° and 90°.

[0103] Such an angle maximizes the impact of the introduced air on the responsiveness of the seal. In particular, this ensures that the air leaving the channel is directed towards the rotating surface opposite the seal, which ensures the generation of a high local overpressure.

[0104] In one embodiment, the depth of the patterns in the second row may be less than or equal to 50% of the predefined set, for example between 30% and 50% of the predefined set.

[0105] In one embodiment, the outer ring sectors form an outer shell and the inner ring sectors have ends arranged end-to-end in the circumferential direction around the axis A.

[0106] In one embodiment, the circumferential ends of the inner ring sectors have an angle of inclination relative to the inner surface of the inner ring sector of between 30° and 90°.

[0107] This inclination of the ends of the inner ring sectors of the seal sectors ensures that the inner ring sectors of the seal sectors move relative to each other.

[0108] Indeed, during use, the radial displacement of the inner ring sectors is not uniform. An inclination of the ends of the inner ring sectors makes it possible to reduce the clearance existing between two inner ring sectors, thus improving the effectiveness of the seal.

[0109] In one embodiment, the seal comprises between 8 and 12 seal sectors.

[0110] For reasons of mechanical strength, space requirements, and to ensure the flatness of the seal surface, it would be preferable to have as many sectors as possible. On the other hand, for aerodynamic reasons, it is necessary to avoid leaks, and therefore to minimize the number of seal sectors. The inventors found that such a number of seal sectors was an optimal compromise between these two opposing effects.

[0111] In one embodiment, the inner surface of the inner ring sector may also comprise after the last pattern an unhollowed surface of the inner surface of the inner ring sector and then a portion of increase in thickness between the unhollowed surface and the downstream end of the inner ring sector.

[0112] Such a profile helps reduce pressure heterogeneity at the seal outlet, which reduces the risk of vibrational instability of the seal due to the wake of the air passing through it.

[0113] For example, the maximum depth of such a dug area can be 0.2 mm.

[0114] In one embodiment, the outer ring sectors of a seal may be a single piece, for example a ferrule. In other words, there is no physical separation between two circumferentially successive outer ring sectors.

[0115] In one embodiment, such a ferrule may be monolithic, i.e. made in a single piece without connection. In such a case, it will be considered that an angular portion of the ferrule can be considered as an external ring sector.

[0116] In one embodiment, the seal further comprises a secondary sealing member disposed radially above the inner ring sector so as to prevent air from axially passing through the seal above the ring sector.

[0117] Such a secondary sealing member ensures the sealing of the seal elements located radially above the internal ring sector.

[0118] In other words, such a secondary sealing member ensures that the only path for air upstream of the seal to pass through it passes radially between the inner surface of the inner ring sector and the outer surface opposite the seal.

[0119] Such a secondary member is known as such to those skilled in the art and may, for example, be chosen from a brush seal, a set of tabs, or a tile.

[0120] According to another of its aspects, the invention also relates to a turbomachine comprising at least one seal as described above.

[0121] For example, at least one of the upstream inner seal (called "FIS" for "forward inner seal" in English), the upstream outer seal (called "FOS" for "forward outer seal" in English) and / or the first seal downstream of the high-pressure compressor (called "CDP" for "compressor discharge pressure" in English) may be a seal as described above.

[0122] In one embodiment, the invention relates to an aeronautical turbomachine as described above, in which the at least one seal is arranged on a cooling air routing circuit, said cooling air routing circuit comprising an inlet taking air downstream of the last disk of a high-pressure compressor and an inlet taking air radially under a combustion chamber which takes the form of an air mouth opening into an air intake housing in communication with the cooling air routing circuit and the seal being chosen from: - an upstream seal located downstream of the high-pressure compressor through which the air taken downstream of the last disc of the high-pressure compressor passes; - an internal downstream seal defining the inlet of said air intake housing and arranged radially below the air intake mouth; and / or - a downstream external seal defining the outlet of said air intake housing and arranged radially under a high pressure distributor. Brief description of the drawings

[0123] [Fig. 1] Figure 1 schematically represents a turbomachine.

[0124] [Fig. 2] Figure 2 schematically represents a seal in one embodiment of the invention.

[0125] [Fig. 3] Figure 3 schematically represents a seal in an embodiment of the invention according to a view different from that of Figure 2.

[0126] [Fig. 4] Figure 4 schematically represents a seal in an embodiment of the invention according to a view different from those of Figures 2 and 3.

[0127] [Fig. 5] Figure 5 represents a joint comprising several joint sectors, in one embodiment of the invention.

[0128] [Fig. 6] Figure 6 represents a sectional view of a turbomachine provided with seals as described according to one embodiment of the invention. Description of the embodiments

[0129] The invention is now described by means of figures, present for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0130] Figure 1 represents, in section along a vertical plane passing through its main axis A, a double-flow turbojet 1. It comprises from upstream to downstream according to the circulation of the air flow, 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.

[0131] In the present application, the relative terms of positioning, for example “upstream”, “downstream”, “internal” and “external”, will be understood in relation to the horizontal axis A of the casing defining the axial direction, traveled in the direction of flow of the main and secondary air flows of the turbomachine.

[0132] Thus, an element called "upstream" will be crossed before an element called "downstream" and an element called "internal" will be closer to axis A than an "external" element.

[0133] In this application, it is understood that the axial direction D A is understood as the direction of the main axis A of the turbomachine; the circumferential direction D c is the one forming a circle around the axial direction D A ; and the radial direction D R , defines a radius of the circle formed by the circumferential direction D c and having as its center the axial direction D A .

[0134] Figure 2 shows a side view of an inner ring sector.

[0135] Figure 2 illustrates in dotted lines the outline of the non-hollowed out internal ring sector to better illustrate what is meant by the hollowed out patterns within the meaning of the invention.

[0136] As shown, the internal surface S int of the ring sector here comprises two rows of patterns 31, 32.

[0137] Figure 2 describes the profile of the internal surface S int of the inner ring sector as seen by air passing through a pattern of the first row 31 and then a pattern of the second row 32.

[0138] In other words, Figure 2 depicts the depth profile along the width of the inner surface of the inner ring sector 13 traversed in the length direction of the patterns.

[0139] For the purposes of the invention, the expression "the width of the internal surface of the internal ring sector traveled in the direction of the length of the patterns" is intended to characterize the dimension of the internal surface S in t of the inner ring sector traveled in a direction offset from the axial direction D A from an angle a equal to the inclination of the patterns.

[0140] It should be recalled here that figure 2, like the other figures in this description, are neither to scale nor even to relative scale.

[0141] The figures are described to a scale that allows the details to be appreciated, but it is not possible to match them to real dimensions.

[0142] In the embodiment shown, the pattern 31 of the first row has an upstream zone 311 in which the depth varies in a decreasing manner and a flat downstream zone 312 of constant non-zero depth H2.

[0143] In the embodiment shown, the upstream zone 311 has a rounded shape, but this is not limiting of the invention.

[0144] The decrease in depth could be constant for example, the upstream zone 311 then forming a slope.

[0145] An upstream zone 311 along which the depth decreases allows the pressure loss at the seal inlet to be reduced.

[0146] In one embodiment, the depth difference H1 between the radially upper end of the internal ring sector and the downstream zone 312 of the pattern 31 of the first row may be greater than or equal to 0.2 mm, for example between 0.2 mm and 4.0 mm.

[0147] In one embodiment, the depth H2 of the downstream zone 312 of the pattern 31 of the first row can be between 1.5 times and 2.5 times the value of the predefined clearance j.

[0148] Depending on the intended application, the predefined clearance j will be between 0.10 mm and 0.45 mm.

[0149] There is no precise limitation of the distribution between the upstream zone 311 and the downstream zone 312 of the pattern 31 of the first row.

[0150] For example, the upstream zone 311 may represent between 10% and 20% of the length of the pattern 31 of the first row.

[0151] By symmetry, the downstream zone 312 can represent between 80% and 90% of the length of the pattern 31 of the first row.

[0152] In one embodiment, the length of the pattern 31 of the first row may represent between 40% and 50% of the width of the internal surface of the internal ring sector 13 traversed in the direction of the length of the patterns.

[0153] Such a length of the first row pattern ensures excellent joint behavior and in particular ensures excellent joint behavior if the latter approaches or deviates from its equilibrium position.

[0154] In one embodiment, a pattern 31 of the first row may be circumferentially spaced from another pattern 31 of the first row, or where appropriate from the end of the internal ring sector 13 by an unhollowed space 41 with a width of between 0.5 mm and 1.5 mm.

[0155] After pattern 31 of the first row of patterns, and since the depth H2 of the first pattern is non-zero, and the latter is separated from pattern 32 of the second row of patterns by an unhollowed portion 43 of the internal surface S in t of the inner ring sector 13 the pattern 31 of the first row of patterns includes an end which has a sharp variation 313 in the depth of the pattern.

[0156] This variation defines a vertical portion 313 which ensures the desired behavior for the seal.

[0157] In one embodiment, the length of the inner surface element 43 S int undug is less than 5% of the width of the inner surface of the inner ring sector 13 traversed in the direction of the length of the patterns.

[0158] In the embodiment shown in Figure 2, the pattern 32 of the second row of patterns has a constant pattern depth H5.

[0159] In one embodiment, the length of the pattern 32 of the second row may represent between 40% and 50% of the width of the internal surface of the internal ring sector 13 traversed in the direction of the length of the patterns.

[0160] In one embodiment, after the pattern 32 of the second row of patterns, and since the depth H5 of the pattern 32 of the second row is non-zero, the pattern 32 of the second row may be circumferentially separated from the circumferential end of the inner ring sector 13 by an unhollowed portion 44 of the inner surface S int of the inner ring sector 13.

[0161] Thus, the pattern 32 of the second row of patterns includes an end which has a sharp variation 323 in the depth of the pattern.

[0162] This abrupt variation defines a vertical portion 323 which ensures the desired behavior for pattern 32 of the second row of patterns.

[0163] In one embodiment, the depth H5 of the pattern 32 of the second row may be less than or equal to 50% of the predefined set j, for example be between 30% and 50% of the predefined set j.

[0164] In one embodiment, a pattern 32 of the second row may be spaced from another pattern 32 of the second row, or where appropriate from the edge of the end of the internal ring sector 13 by an unhollowed space 42 with a width of between 0.5 mm and 1.5 mm.

[0165] In one embodiment, which is that shown in FIG. 2, the pattern 32 of the second row can be separated from the downstream of the internal surface S in t by a portion of surface 44 not hollowed out not belonging to a pattern.

[0166] In one embodiment, this non-hollowed surface portion 44 can itself be axially separated from the downstream edge 45 of the internal surface S in t of the internal ring sector 13 by a dug downstream zone 442.

[0167] For example, zone 442 may have a linear variation in depth, up to the downstream edge 45 of the internal ring sector 13.

[0168] For example, the maximum H7 depth of the downstream zone 442 may be greater than or equal to 0.2 mm.

[0169] Such a profile of the downstream zone 442 of the internal ring sector 13 makes it possible to ensure continuity of pressure.

[0170] In one embodiment, the length of the portion between the pattern 32 of the second row of patterns and the downstream edge 45 may be less than or equal to 10% of the width of the internal surface of the internal ring sector 13 traveled in the direction of the length of the patterns, or even between 6% and 10% of the width of the internal surface of the internal ring sector 13 traveled in the direction of the length of the patterns.

[0171] The invention is not limited by the relative size of the un-hollowed portion 44 and the downstream zone 442. Thus, the portion 44 may represent between 10% and 20% of the entire downstream length of the second pattern, i.e., the portions 44 and the zone 442.

[0172] By symmetry, the downstream zone 442 can represent between 80% and 90% of the entire zone downstream of the second pattern, that is to say of the portions 44 and of the zone 442.

[0173] In one embodiment, the width of the inner surface of the inner ring sector 13 traveled in the axial direction may be between 20 mm and 40 mm.

[0174] For all practical purposes, it is specified here that the width of the internal surface of the internal ring sector 13 traveled in the direction of the length of the patterns as defined above is then equal to the width of the internal surface of the internal ring sector 13 traveled in the axial direction D. A divided by the cosine of the inclination a.

[0175] Figure 2 further illustrates a channel 501.

[0176] This channel 501 comprises a first opening 502 and a second opening 503.

[0177] The first opening 502 is an opening on the upstream face of the inner ring sector. This first opening 502 will be described more explicitly in connection with Figure 3.

[0178] The channel 501 further comprises a second opening 503, which opens into the pattern 32 of the second row of patterns.

[0179] Figure 2 further illustrates the angle y of the bend of channel 501.

[0180] The y angle of the 501 channel bend is between 60° and 90°.

[0181] This embodiment ensures that the air coming from the channel is sent towards the surface 500 opposite the internal surface S int of the seal and that it allows after its meeting with the surface 500.

[0182] In one embodiment, the diameter of the channel 501 does not vary between its inlet diameter DI and its outlet diameter D2.

[0183] In one embodiment, the diameter of the channel 501 may vary between its inlet diameter DI and its outlet diameter D2.

[0184] In one embodiment, the diameter of the channel will widen, i.e., DI will be smaller than D2.

[0185] In one embodiment, the inlet diameter DI may be greater than or equal to 0.5 mm.

[0186] The inventors have in fact found that such a diameter for the channel 501 allows it to precisely fulfill its function without jeopardizing the structural integrity of the seal.

[0187] In one embodiment, channel 501 is not necessarily spherical and may have an oval, or elliptical, opening.

[0188] We will then nevertheless speak of the inlet diameter DI for the channel 501, considering the diameter of the circle whose surface area would be equal to the surface area of ​​the inlet opening 502 of the channel.

[0189] In one embodiment, the same applies to the outlet opening 503 and by analogy we will speak of outlet diameter D2 for the channel 501 by considering the diameter of the circle whose surface area would be equal to the surface area of ​​the outlet opening 503 of the channel.

[0190] Figure 3 schematically illustrates the upstream face of an inner ring sector 13 as seen by the incoming air flow.

[0191] In the embodiment shown, the first openings 502 of the channels are arranged radially above non-hollowed portions 41 of the internal ring sector 13. This embodiment makes it possible to ensure that a channel 501 opens above a pattern of the second row when the latter is offset relative to a pattern of the first row.

[0192] This is however not necessary to achieve the technical effect, and in one embodiment, the first openings 502 of the channels 501 may be arranged radially above first patterns, for example centered above first patterns.

[0193] Figure 4 illustrates the internal surface S int of an inner ring sector as may be in one embodiment of the invention.

[0194] Figure 4 further includes an inset showing a zoom view of a pattern 32 of the second row of patterns.

[0195] As shown, the patterns form two rows, an upstream row formed by patterns 31 and a downstream row formed by patterns 32.

[0196] Furthermore, each pattern is separated from the next by an unhollowed surface of the internal surface S intof the internal ring sector 13, identified by the symbol 41 between two patterns 31 of the first row, by the symbol 42 between two patterns 32 of the second row, or by the symbol 43 between a pattern 31 of the first row and 32 of the second row.

[0197] Furthermore, the patterns may or may not be spaced from the downstream edge of the inner ring sector 13 by an uncarved space 44 of the inner surface S int of the inner ring sector 13, not belonging to the pattern.

[0198] In one embodiment, the inner surface of the inner ring sector 13 may comprise, between the unhollowed space 44 and its downstream edge 45, a hollowed space 442.

[0199] Preferably, the space 44 between the pattern of the second row 32 and the downstream edge 45 comprises a non-hollowed portion 44 of the internal surface S int of the internal ring sector 13, and a portion 442 forming a chamfer, that is to say whose depth increases.

[0200] This embodiment makes it possible to reduce the pressure heterogeneity at the outlet of the seal.

[0201] As discussed above, the patterns are elongated in shape, and are oblique to the axial direction D A , that is to say presents with this direction an inclination a.

[0202] The air flow F is not aligned with the axial direction, but has a non-zero tangential speed, which corresponds to that which it has in practice when the flat surface opposite the seal 500 is rotated in the circumferential direction D c .

[0203] In one embodiment, the width of a pattern may be greater than or equal to 0.5 mm.

[0204] In one embodiment, the width of a pattern may be between 0.5 and 5.0 mm or even between 2.0 mm and 5.0 mm.

[0205] Preferably, the width of a pattern 31 of the first row and the width L10 of a pattern 32 of the second row is identical.

[0206] In the case shown where the width of a pattern varies, the width of the pattern may preferably be considered to be the width at the widest point of the pattern, for example the width of the downstream end of the pattern.

[0207] As shown in Figure 4, the first and second rows may not have the same number of patterns.

[0208] In one embodiment, the tilt angle a is between 30° and 90°.

[0209] This inclination makes it possible to increase the length of the patterns carved on the internal surface S int of the inner ring sector 13.

[0210] It is shown in Figure 4 that the patterns 32 of the second row are offset by approximately half a width relative to the patterns 31 of the first row.

[0211] Although the figures are neither to scale nor even to relative scale, in one embodiment the patterns 32 of the second row are actually offset from the patterns 31 of the first row, for example by approximately half a pattern width.

[0212] This offset ensures that the air diverted by a pattern 31 of the first row of patterns then passes through a pattern 32 of the second row of patterns.

[0213] The path followed by the air flow F passing through the patterns is shown by arrows in Figure 4.

[0214] As described above, the length L9 of the pattern 32 of the second row can represent between 40% and 50% of the width of the internal surface S int of the inner ring sector 13 traveled in the direction of the length of the patterns.

[0215] The insert in Figure 4 also makes it possible to show the angle 5 of the upstream portion of pattern 32 of the second row of patterns.

[0216] Figure 4 finally shows what is meant by the width of pattern 32 of the second row of patterns and the latter is identified by the length L10.

[0217] In one embodiment L10 may be less than or equal to four times D2, for example less than or equal to 5.0 mm, for example between 2.0 and 5.0 mm.

[0218] Figure 5 depicts a seal that includes multiple seal sectors. As shown, the outer ring sector 11 may be common to multiple seal sectors, or even all seal sectors.

[0219] For reasons of representation, the external surface facing the seal is not shown in Figure 5.

[0220] In one embodiment and as can be seen in Figure 5, all of the sealing gasket sectors, and more specifically the internal and external ring sectors, make it possible to give the entire sealing gasket an annular shape.

[0221] Figure 5 also shows the circumferential space between two sealing gasket sectors 21, and shows that the return member 12 may comprise an external arm 12a and an internal arm 12b.

[0222] Figure 5 further illustrates a secondary sealing member 14 as described above. The secondary sealing member may include a plurality of circumferentially distributed elements.

[0223] Although the representation of the secondary sealing member 14 is truncated in Figure 5 to make the elements 11 and 12 visible, the secondary sealing member 14 may cover the entire circumference of a seal as described above.

[0224] For example, there may be as many, more or fewer portions of secondary sealing member as there are seal sectors.

[0225] Furthermore, Figure 5 illustrates the first openings 502 and second openings 503 of the channels, visible here respectively on the upstream face of the internal ring sectors 13, and on the internal surface S in t of the inner ring sectors.

[0226] Figure 6 represents a portion of the turbomachine visible in Figure 1, and illustrates that the latter can be provided with seals conforming to those described above.

[0227] In the embodiment shown, the turbomachine portion has three seals: an upstream inner seal 62 (“FIS”), an upstream outer seal 63 (“FOS”) and a first seal downstream of the high-pressure compressor 61 (“CDP”).

[0228] Such seals are now described in connection with Figure 6 which is only one example of a configuration for an air cooling path in a turbomachine, and those skilled in the art will be able to identify an upstream external seal 63 (“FOS”) an upstream internal seal 62 (“FOS”) and a first seal downstream of a high pressure compressor 61 (“CDP”) in other geometries of the cooling circuit.

[0229] Figure 6 shows a diagram of a cooling circuit of a turbomachine.

[0230] In the embodiment shown, air is taken downstream of the last compressor disc 401 as well as below the combustion chamber 5.

[0231] The air taken downstream of the last compressor disc 401 first passes through the seal 61, which is located radially below the inlet of the combustion chamber 5.

[0232] The seal 61 defines the quantity of air for the cooling circuit 401 taken downstream of the last disc of the high pressure compressor 4.

[0233] The air taken from below the combustion chamber can, for example, be taken through an air inlet, opening into a housing between the upstream outer seal 63 and the upstream inner seal 62.

[0234] In Figure 6, these two sealing gaskets respectively delimit the inlet and the outlet of such a housing.

[0235] The seal 62 is crossed by the air coming from the high pressure compressor 401 wishing to enter this housing, and whether it is then used for the cooling circuit 82 or whether it is intended for the purge circuit 81.

[0236] The seal 63 delimits the outlet of the air intake housing, and limits the flow of air reaching the purge circuit 81.

[0237] For example, the seal 62 may be located radially below the air intake mouth, while the seal 63 may be located below the first distributor of the high pressure turbine 701.

[0238] In Figure 6, the purge circuit opens between the high pressure distributor 701 and the first high pressure rotor blade 702.

[0239] In the embodiment shown, it will be noted that the surface facing the seals 62 and 63 is an external surface of a stage of the rotor of the high pressure turbine.

[0240] Figure 6 shows a turbomachine for which the three particular seals 61, 62, 63 are as described above, but it does not go beyond the scope of the invention if only one of these seals conforms to what is described above.

[0241] In the following, the seal 61 will be described, but it should be noted that what is described for this seal can also be applied to the other seals.

[0242] In one embodiment, which is the one shown, the surface 500 facing the seal comprises a groove filled with a varnish 51.

[0243] This embodiment ensures that in abnormal operation, and if it were to come into contact with the surface opposite the seal, the internal surface of the seal does not damage the surface 500 itself but only the varnish 51.

[0244] Furthermore, the varnish 51 may be transparent, which then allows even easier control since the surface 500 is visible under the varnish and it is possible to visually see, without having to remove the varnish, whether or not the use of the seal has caused any degradation of the facing surface 500.

[0245] In one embodiment, the surface 500 facing the seal, whether or not it is provided with a groove and varnish 51, may be connected to a weight 58.

[0246] This embodiment ensures that the facing surface of the seal 500 remains flat throughout operation of the seal and minimizes the risk of the inner ring sector 13 of the seal 100 coming into contact with the facing surface 500.

[0247] In Figure 6, the air flow through the seals is shown by arrows, and the axis A of the turbomachine is also present.

[0248] Figure 6 shows how the air 401 taken from the outlet of the high-pressure compressor 4 can reach a moving blade 702 of the hot part of the turbomachine, here of the high-pressure turbine 6, arranged after the combustion chamber 5. In an alternative mode, the air can also exit the cooling circuit via the bleed outlet 81, after passing through the upstream inner seal 62 and upstream outer seal 63.

[0249] A portion of the cooling air passes via path 82 to be injected directly into the cooling circuit of a moving blade 702 of the hot part of the turbomachine, here a moving blade 702 of the high-pressure turbine.

[0250] The purge outlet of the cooling circuit is here located between a fixed blade 701 and a moving blade 702 of the high pressure turbine 6.

[0251] Figure 6 also illustrates that the surface 500 facing the seal may be a surface of a rotor rotatably mounted about the axis A. For example, the surface 500 may be a surface of the rotor of the high-pressure turbine 6.

Claims

Claims

1. Seal configured to ensure a predefined clearance (j) between said seal and an external surface (500) of a rotor rotatably mounted around an axis A and arranged opposite the seal, the axis A defining an axial direction (D A ), the seal extending circumferentially around the axis A and comprising a plurality of seal sectors distributed circumferentially around the axis A, each seal sector comprising, radially with respect to the axis A, an internal ring sector (13) connected to an external ring sector (11) by a return member (12), the seal being characterized in that the radially internal surface (S int) of each inner ring sector (13) comprises at least one pattern (31, 32) hollowed out from the radially inner surface of the inner ring sectors, the inner ring sector (13) further comprising at least one channel (501) connecting a first opening (502) which opens onto the upstream face of the inner ring sector and a second opening (503) which opens into one of the patterns hollowed out from the radially inner surface (S int ) inner ring sectors.

2. A seal according to claim 1, wherein the radially inner surface of each inner ring sector comprises at least two rows of patterns, each of the patterns having an elongate shape extending in a direction oblique to the axial direction and being separated from another pattern by an unhollowed portion of the inner surface.

3. A seal according to claim 1 to 2, wherein the angle of inclination of each pattern (a) relative to the axial direction is greater than or equal to 30°.

4. A seal according to claim 1 to 3, wherein the diameter of the channel (501) increases between the first (502) and the second opening (503).

5. A seal according to any one of claims 2 to 4, wherein the radially inner surface (S int ) of each of the internal ring sectors (13) comprises a first and a second row of patterns, and in which each pattern (31) of the first row of patterns has a planar downstream zone (312) of constant depth (H2) and non-zero and an upstream pattern zone (311) in which the depth varies in a decreasing manner while remaining greater than the constant depth of the downstream pattern zone.

6. A seal according to any one of claims 2 to 5, wherein the radially inner surface (S int ) of each of the inner ring sectors (13) comprises a first and a second row of patterns, the patterns of the first Tl row of patterns being offset in the circumferential direction (D c ) opposite the patterns of the second row of patterns.

7. A seal according to any one of claims 2 to 6, wherein the radially inner surface (S int ) of each of the internal ring sectors (13) comprises a first and a second row of patterns, and in which each pattern (32) of the second row of patterns is connected to at least one channel (501) connecting a first opening (502) which opens onto the upstream face of the internal ring sector and a second opening (503) which opens into the pattern.

8. A seal according to any one of claims 2 to 7, wherein the radially inner surface (S int ) of each of the internal ring sectors (13) comprises a first and a second row of patterns and in which the width (L10) of the downstream end of the patterns (32) of the second row of patterns is greater than or equal to 4 times the diameter (D2) of the second opening (503).

9. A seal according to any one of claims 2 to 8, wherein the radially inner surface (S int) of each of the internal ring sectors (13) comprises a first and a second row of patterns and in which the patterns (32) of the second row of patterns comprising a second opening (503) have a flared upstream portion falling within a cone whose angle is between 10° and 45°.

10. A seal according to any one of claims 1 to 9, in which the channel comprises an elbow forming an angle (y) between 60° and 90°.

11. A turbomachine comprising at least one seal according to one of claims 1 to 10.

12. Aeronautical turbomachine in which at least one seal according to any one of claims 1 to 10 is arranged on a cooling air routing circuit, said cooling air routing circuit comprising an inlet taking air (401) downstream of the last disc of a high pressure compressor (4) and an inlet taking air radially under a combustion chamber (5) which takes the form of an air mouth opening into an air intake housing in communication with the cooling air routing circuit and the seal being chosen from: - an upstream seal (61) located downstream of the high pressure compressor through which the air taken downstream of the last disc of the high pressure compressor passes; - a downstream internal seal (62) defining the inlet of said air intake housing and arranged radially under the air intake mouth; and / or - a downstream external seal (63) defining the outlet of said air intake housing and arranged radially under a high pressure distributor (701).

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