Seal for a turbine engine

Abstract

The invention relates to a seal (100) which is configured to ensure a predefined clearance (j) between the seal and an outer surface (500) of a rotor which is rotatably mounted about an axis A arranged facing the seal, the seal extending circumferentially about the axis A and comprising a plurality of seal segments which are distributed circumferentially about the axis A, each seal segment comprising an inner ring segment (13) which is connected to an outer ring segment (11) by a return member (12), the seal being characterised in that the inner surface (Sint) of each inner ring segment comprises at least one row of patterns which are carved into the inner surface of the inner ring segments, each of the patterns having an elongate shape extending in an oblique direction with respect to the axial direction and being separated from another pattern by an uncarved portion (41, 42, 43) of the inner surface.

Description

Description Title of the invention: Gasket for turbomachine Technical Field

[0001] This disclosure relates to a particular seal, as well as to a turbomachine comprising such a seal. 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 nevertheless has the disadvantage that the wear of the wipers by friction against the abradable elements increases the seal clearance 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] Therefore, there remains a need for seals that wear less over their lifetime than labyrinth seals. Statement of the invention

[0009] The present invention aims precisely to meet this need.

[0010] To this end, it proposes a seal configured to ensure a predefined clearance between said seal and an external surface of a rotor rotatably mounted around an axis A 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 an internal ring sector connected to an external ring sector by a return member, the seal being characterized in that the internal surface of each internal ring sector comprises at least one row of patterns hollowed out from the internal surface of the internal ring sectors, each of the patterns having an elongated shape extending in an oblique direction relative to the axial direction and being separated from another pattern by a non-hollowed portion of the internal surface.

[0011] Such a seal architecture differs radically from a labyrinth seal.

[0012] However, the internal surface of the internal ring sector does ensure aerodynamic sealing by ensuring a predefined clearance with the facing surface.

[0013] 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.

[0014] 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.

[0015] In one embodiment, the circumferential distribution is regular, and each seal sector then represents an equal portion of the circumference of the seal.

[0016] 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 seal will be returned to the predefined clearance with respect to a spring behavior of the internal ring sectors ensured in particular by the return members.

[0017] More precisely, if the seal clearance becomes smaller than the preset clearance, the pressure radially under the inner surface of the ring sectors increases and the inner ring sector then moves so as to increase the clearance, whereas if the seal clearance becomes greater than the predefined clearance, the return member exerts a force greater than the pressure exerted radially under the internal surface of the internal ring sectors, the latter then returning to their equilibrium positions, i.e. to the predefined clearance.

[0018] This aerodynamic balance prevents the internal surface of the internal ring sector from coming into contact with the opposite surface at any time, and the seal differs in this from labyrinth seals. This avoids the wear problem that can be encountered with conventional labyrinth seals.

[0019] 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.

[0020] In one embodiment, the clearance between the internal surface of the internal ring sector and the radially facing surface may be between 0.1 and 1.0 mm or even between 0.5 mm and 1.0 mm.

[0021] The patterns carved from the inner surface of the inner ring sector allow the behavior of the seal 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.

[0022] 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.

[0023] The special geometry, called "L-shaped", of the second pattern allows the pressure under the seal to be increased even further, compared to other simpler pattern geometries.

[0024] 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.

[0025] In one embodiment, axis A may be the main axis of a turbomachine.

[0026] Patterns or parts of patterns are said to be elongate. 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.

[0027] The second dimension of the pattern, in the plane of the inner surface of the inner ring sector will be arbitrarily called length.

[0028] It is not outside the scope of the invention if the width is greater than the length.

[0029] 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.

[0030] Thus, and as described, the length of a pattern is in an oblique direction relative to the axial direction.

[0031] 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.

[0032] In one embodiment, the patterns have an angle of inclination relative to the axial direction, this angle of inclination being greater than or equal to 30°.

[0033] 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.

[0034] In one embodiment, the angle of inclination of the patterns is between 30° and 60°, or even between 30° and 45°.

[0035] 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.

[0036] 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.

[0037] The surface facing the seal is a surface of a rotor mounted to rotate around the axis A, for example the rotor of a high-pressure turbine of an aeronautical turbomachine. In one embodiment, the patterns may be tilted in the same direction as the direction of rotation of the rotor.

[0038] 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.

[0039] 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.

[0040] In one embodiment, each inner surface of the inner ring sectors comprises a plurality of rows of patterns in the radial direction, each formed from a plurality of patterns in the circumferential direction.

[0041] For example, each inner surface of the inner ring sectors comprises a first and a second row of patterns, each of the rows comprising a plurality of patterns distributed in the circumferential direction.

[0042] In an embodiment where the joint comprises two rows of patterns, the patterns of the first row of patterns and the patterns of the second row of patterns have a flat portion over which the depth does not vary, and the depth of this flat portion will be considered to be the depth of the pattern. If the patterns do not have such a flat portion or if they have more than one flat portion, the depth of the pattern will be called the average depth of the pattern.

[0043] The embodiments described now make it possible to ensure a faster return of the seal to its predefined clearance, and therefore to its equilibrium position.

[0044] Furthermore, they ensure that the inner surface of the inner ring sector does not come into contact with the facing surface in intended or even accidental operating modes.

[0045] In an embodiment where the seal comprises at least two rows of patterns, the patterns of the first row of patterns have a depth greater than or equal to the patterns of the second row of patterns.

[0046] It is understood that the first row of patterns is the first row encountered by the airflow passing the seal. In the case where there is only one row of patterns, the first row is the row of patterns.

[0047] If there are two rows of patterns, the first row of patterns can also be characterized as the "upstream row", and the second row of patterns as the "downstream row".

[0048] In one embodiment, each pattern of the first row of patterns has a planar downstream pattern area of ​​constant, non-zero depth and an upstream pattern area in which the depth varies in a decreasing manner while remaining greater than the constant depth of the downstream pattern area.

[0049] 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.

[0050] In one embodiment, the upstream area of ​​each pattern of the first row of patterns may have a rounded, i.e. convex, shape.

[0051] 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.

[0052] Furthermore, in an embodiment where the seal comprises at least two rows of patterns, 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 pattern of the first row is non-zero, this embodiment ensures that air traveling through the first pattern encounters a wall directed in the radial direction at the end of the first pattern.

[0053] 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, which increases the performance of the seal.

[0054] In one embodiment, the depth of the downstream portion of the first row pattern may be between 1.5 times and 2.5 times the predefined clearance for the seal.

[0055] The inventors have in fact noted that these depth values ​​ensure excellent pressure distribution in the seal, which improves the seal's effectiveness.

[0056] In an embodiment where the inner surface of each inner sector comprises at least two rows of patterns, each pattern of the second row of patterns has a planar downstream pattern zone of constant, non-zero depth and an upstream pattern zone 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 zone.

[0057] 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.

[0058] In one embodiment, each inner surface of the inner ring sectors includes a first and a second row of patterns, the first row of patterns being offset in the circumferential direction from the second row of patterns.

[0059] 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.

[0060] 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 sealing joint.

[0061] In one embodiment, the inner surface of the inner ring sector may also comprise more than two rows of patterns, for example between two and five rows of patterns.

[0062] In one embodiment, the inner surface of each of the first and second rows of patterns comprises a plurality of patterns distributed in the circumferential direction.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] In such an embodiment, the circumferential ends of the inner ring sectors may have an angle of inclination relative to the circumferential direction of between 30° and 90°.

[0068] This inclination of the circumferential ends of the inner ring sectors of the joint sectors allows for movement of the inner ring sectors of the joint sectors relative to each other.

[0069] 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 efficiency of the seal.

[0070] In one embodiment, the seal comprises between 8 and 12 seal sectors.

[0071] For reasons of mechanical strength, space requirements, and to ensure the flatness of the seal surface, it is preferable to have as many sectors as possible. However, for aerodynamic reasons, it is necessary to avoid leaks and therefore 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] Such a secondary sealing member makes it possible to ensure the sealing of the elements of the seal located radially above the internal ring sector. In other words, such a secondary sealing member ensures that the only path allowing air upstream of the seal to pass through it passes radially between the internal surface of the internal ring sector and the external surface opposite the seal.

[0076] 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.

[0077] According to another of its aspects, the invention also relates to a turbomachine comprising at least one seal as described above.

[0078] In one embodiment, the turbomachine comprises a circuit for conveying cooling air to a high-pressure rotor disk, the cooling air conveying circuit comprising at least one seal described above, said cooling air conveying circuit comprising an inlet taking air downstream of the last disk of the high-pressure compressor, an inlet taking air radially under the combustion chamber and an air outlet opening into a cooling housing of the high-pressure rotor disk and the at least one seal being arranged at one of the positions below: - downstream of the inlet taking air from the high pressure compressor, radially below the last rectifier of the high pressure compressor; - radially below a cooling air injector in fluid communication with the inlet taking air radially below the combustion chamber; - radially between the injector and the foot of the high pressure distributor and arranged so as to prevent leakage of air intended to cool the high pressure rotor.

[0079] In one embodiment, the turbomachine comprises a circuit for conveying cooling air to a high-pressure rotor disk, the cooling air conveying circuit comprising at least one seal described above, said cooling air conveying circuit comprising an inlet taking air downstream of the last disk of the high-pressure compressor, an inlet taking air radially under the combustion chamber and an air outlet opening into a cooling housing of the high-pressure rotor disk and the at least one seal being chosen from: - the first seal downstream of the high pressure compressor crossed by the air taken downstream of the last disc of the high pressure compressor; - the front internal seal defining the inlet of said air intake housing and arranged below the air intake mouth; - the front outer seal defining the outlet of said air intake housing and arranged below the high pressure distributor.

[0080] For example, and according to the terminology of the field, at least one of the front inner seal (called "FIS" for "forward inner seal" in English), the front outer seal (called "FOS" for "forward outer seal" in English) and / or the first seal sealing downstream of the high pressure compressor (called “CDP” for “compressor discharge pressure” in English) can be a seal as described above.

[0081] Preferably, the first seal downstream of the compressor disc ("CDP") is as described above.

[0082] Reference is made to rectifiers with the meaning that this term usually has in the field, that is to say an air straightening stator blade.

[0083] It has been found that these seals offer a much better service life than labyrinth seals, thus ensuring that the performance of the turbomachine is maintained throughout its service life.

[0084] In one embodiment, the facing face of the seal comprises a groove filled with a varnish.

[0085] In such an embodiment, the inner surface of the inner ring sector is not likely to be damaged by contact with the facing surface, even in the event of abnormal operation.

[0086] In fact, it would only come into contact with the varnish and not the opposite face.

[0087] In such an embodiment, the varnish is preferably transparent.

[0088] This allows for a visual inspection of the surface opposite the seal without the need to remove the varnish. This makes the inspection easier.

[0089] In one embodiment, the seal as described above is arranged downstream of the inlet taking air from the high pressure compressor, radially under the last rectifier of the high pressure compressor and the surface facing said seal comprises a groove filled with a transparent varnish.

[0090] In one embodiment, the facing surface of the seal may be integrated into the top of a rotor disc or coupled to a flyweight.

[0091] This embodiment ensures that the surface facing the seal remains flat, even when the turbomachine is in operation.

[0092] A flatter facing surface of the seal ensures better performance of the seal and therefore better performance of the entire turbomachine. Brief description of the drawings

[0093] [Fig. 1] Figure 1 shows a plurality of seal sectors in one embodiment of the invention.

[0094] [Fig. 2] Figure 2 shows in another view, the sealing gasket sectors of Figure 1.

[0095] [Fig. 3] Figure 3 shows a bottom view of the inner surface of the inner ring sector of a seal sector in one embodiment of the invention.

[0096] [Fig. 4] Figure 4 shows the depth profile along an airflow path passing through a seal in one embodiment of the invention.

[0097] [Fig. 5] Figure 5 shows a sectional view of a turbomachine.

[0098] [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

[0099] 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.

[0100] As indicated, the invention relates to a 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 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 an internal ring sector 13 connected to an external ring sector 11 by a return member 12, the sealing seal being characterized in that the internal surface S int of each inner ring sector comprises at least one row of patterns hollowed out from the inner surface of the inner ring sectors 13, each of the patterns having an elongated shape extending in a direction oblique to the axial direction D A and being separated from another pattern by an unhollowed portion 41, 42, 43 of the internal surface.

[0101] As shown in Figure 1, the outer ring sector 11 may be common to several sectors of the seal, or even to all sectors of the sealing gasket.

[0102] For reasons of representation, the external surface facing the seal is not shown in Figure 1.

[0103] In one embodiment and as can be seen in Figure 1, all of the joint sectors, and more specifically the internal and external ring sectors, make it possible to give the entire joint an annular shape.

[0104] Figure 1 also shows the circumferential space between two seal sectors 21, and shows that the return member 12 can comprise an external arm 12a and an internal arm 12b.

[0105] The return member 12 will be described in more detail with Figure 2.

[0106] Figure 1 further illustrates a secondary sealing member 14 as described above. The secondary sealing member may comprise a plurality of circumferentially distributed elements.

[0107] Although the representation of the secondary sealing member 14 is truncated in FIG. 1 to make the elements 11 and 12 visible, the secondary sealing member 14 covers the entire circumference of a seal as described above.

[0108] For example, there may be as many, more or fewer portions of secondary sealing organ as there are seal sectors.

[0109] Generally in this description, the use of positioning terms should be understood in relation to the air flow passing through the seal.

[0110] Thus, a so-called "upstream" element will be encountered by the air flow before a so-called "downstream" element, and a so-called "internal" element will be placed closer to the air flow than a so-called "external" element.

[0111] Figure 2 shows a sectional view of the elements visible in Figure 1.

[0112] Figure 2 further shows the surface 500 facing the seal, and also specifies a number of dimensions which will be described and which represent preferred embodiments of the invention.

[0113] Figure 2 also represents the main dimensions in relation to which the different elements of a joint according to the invention are described.

[0114] Among them, the axial direction D Awhich is understood as the direction around which the joint extends; the circumferential direction D c in which the seal extends, and forming a circle around the axial direction D A ; and the radial direction D R , which defines a radius of the circle formed by the circumferential direction D c and having as its center the axial direction D A .

[0115] The elements El and PI characterize the attachment of the return member 12 to the external ring sector 11.

[0116] In one embodiment E1, the connecting surface between the return member 12 and the external ring sector 11 may be greater than or equal to 4 mm, for example between 4 mm and 8 mm.

[0117] In one embodiment, PI the thickness of the portion of the return member 12 linked to the ring sector 11, and measured from the internal surface of the external ring sector 11 may be greater than or equal to 5 mm, for example between 5 mm and 10 mm.

[0118] In one embodiment, the return member can be divided into an outer arm 12a and an inner arm 12b. This ensures a lower mass of the entire device, while giving the whole assembly entirely satisfactory return and flexibility properties.

[0119] For example, the thickness E3 of the external arm 12a may be greater than or equal to 0.7 mm, for example between 0.7 mm and 2 mm.

[0120] For example, the thickness E4 of the inner arm 12b may be greater than or equal to 0.7 mm, for example between 0.7 mm and 2 mm.

[0121] In one embodiment, the thickness E3, E4 of the outer 12a and inner 12b arms are equal.

[0122] In one embodiment, the thickness E5 of the return member 12 may be greater than or equal to 2.5 mm, for example between 2.5 mm and 5.0 mm.

[0123] The thickness E5 of the return member 12 is understood, in the case where it is divided into two thinner arms, as the distance between the internal surface of the internal arm and the external surface of the external arm.

[0124] The precise values ​​chosen for E3, E4 and E5 make it possible to precisely size the return force of the return member 12, and therefore to influence the operation of the joint, as well as the definition of the predefined clearance j.

[0125] In an embodiment E2, the connecting surface between the return member 12 and the internal ring sector 13 may be greater than or equal to 4 mm, for example between 4 mm and 8 mm.

[0126] In one embodiment, P2 is the thickness of the portion of the return member 12 connected to the internal ring sector 13, and measured from the external surface of the sector of internal ring 13 may be greater than or equal to 5 mm, for example between 5 mm and 10 mm.

[0127] In one embodiment, the thickness E6 of the inner ring sector 13 may be between 2.0 mm and 5.0 mm.

[0128] Such dimensions represent an excellent compromise between the possibility of ensuring hollow patterns of sufficient size and a reduced weight of the entire joint.

[0129] In one embodiment, the clearance j between the internal surface of the internal ring sector 13 and the radially facing surface 500 may be between 0.1 and 1.0 mm or even between 0.5 mm and 1.0 mm.

[0130] This clearance j corresponds to a target airflow in turbomachinery fans for engine cooling applications.

[0131] Figure 2 also shows the angle of inclination of the radial ends of the inner ring sector 13. As described above, this inclination ensures that movement of the inner ring sectors relative to each other is possible, thereby reducing the spacing between two sectors during operation.

[0132] Figure 2 also shows the spacing between two joint sectors 11 which is preferably less than or equal to 0.3 mm.

[0133] This spacing helps ensure leakage is minimized while still allowing enough space for the inner ring sectors to move relatively to each other.

[0134] Indeed, the internal ring sectors 13 may be stressed slightly differently from each other, and it is important that they have a certain degree of freedom to be able to accommodate this difference in stress.

[0135]

[0136] Figure 3 shows a view of the inner surface S in t of the inner ring sector 13, which carries the patterns.

[0137] As shown, the patterns form two rows, an upstream row formed by patterns 31 and a downstream row formed by patterns 32.

[0138] Furthermore, each pattern is separated from the next by an unhollowed surface of the internal surface S in t of the inner ring sector 13, marked 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.

[0139] 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.

[0140] In one embodiment, the internal surface of the internal ring sector 13 may comprise, between the unhollowed space 44 and its downstream edge 45, a hollowed space 442.

[0141] 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.

[0142] This embodiment makes it possible to reduce the pressure heterogeneity at the seal outlet.

[0143] 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.

[0144] The air flow F is not aligned with the axial direction, but has a non-zero tangential velocity, which corresponds to that which it has in practice when the flat surface opposite the seal is rotated in the circumferential direction D c .

[0145] In one embodiment, the width of a pattern may be greater than or equal to 4 mm.

[0146] As shown in Figure 3, the first and second rows may not have the same number of patterns.

[0147] In one embodiment, the tilt angle a is between 30° and 90°.

[0148] This inclination makes it possible to increase the length of the patterns carved on the internal surface S in t of the inner ring sector 13.

[0149] It is shown in Figure 3 that the patterns 32 of the second row are offset by approximately half a width relative to the patterns 31 of the first row.

[0150] Although the figures are neither to scale nor even to relative scale, in one embodiment the patterns are actually offset.

[0151] 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.

[0152] The path followed by the air flow F passing through the patterns is shown by arrows in Figure 3.

[0153] Figure 4 describes the profile of the internal surface S intof the inner ring sector 13 as seen by air passing through a pattern of the first row 31 and then a pattern of the second row 32.

[0154] In other words, Figure 4 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.

[0155] 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 int of the inner ring sector 13 traveled in a direction offset from the axial direction D A from an angle a equal to the inclination of the patterns.

[0156] It should be recalled here that figure 4, like the other figures in this description, are neither to scale nor even to relative scale.

[0157] 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.

[0158] 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.

[0159] In the embodiment shown, the upstream zone 311 has a rounded shape, but this is not limiting of the invention.

[0160] The decrease in depth could be constant for example, the upstream zone 311 then forming a slope.

[0161] An upstream zone 311 along which the depth decreases allows the pressure loss at the seal inlet to be reduced.

[0162] In one embodiment, the depth difference H1 between the upstream end of the upstream zone 311 of the pattern 31 of the first row 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 0.5 mm.

[0163] 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.

[0164] Depending on the intended application, the predefined clearance j will be between 0.10 mm and 0.45 mm.

[0165] 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.

[0166] For example, the upstream zone 311 may represent between 10% and 20% of the length of the pattern 31 of the first row.

[0167] By symmetry, the downstream zone 312 can represent between 80% and 90% of the length of the pattern 31 of the first row.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] This variation defines a vertical portion 313 which ensures the desired behavior for the seal.

[0173] In one embodiment, the length of the inner surface element 43 S in t 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.

[0174] In the embodiment shown in Figure 4, the pattern 32 of the second row of patterns has an upstream zone 321 in which the depth of the pattern varies increasing from the internal surface S int of the internal ring sector 13 (element 43) and a downstream flat zone 322 of constant depth H5 and not zero.

[0175] There is no precise limitation of the distribution between upstream zone 321 and downstream zone 322 of pattern 32 of the second row.

[0176] For example, the upstream zone 321 may represent between 10% and 20% of the length of the pattern 32 of the second row.

[0177] By symmetry, the downstream zone 322 can represent between 80% and 90% of the length of the pattern 32 of the second row.

[0178] 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.

[0179] 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 e 13.

[0180] 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.

[0181] This abrupt variation defines a vertical portion 323 which ensures the desired behavior for pattern 32 of the second row of patterns.

[0182] 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.

[0183] 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.

[0184] In one embodiment, which is that shown in FIG. 4, 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.

[0185] In one embodiment, this non-hollowed surface portion 44 can itself be axially separated from the downstream edge 45 of the internal surface S intfrom the inner ring sector 13 by a dug downstream zone 442.

[0186] For example, zone 442 may have a linear variation in depth, up to the downstream edge 45 of the internal ring sector 13.

[0187] For example, the maximum H7 depth of the downstream zone 442 may be greater than or equal to 0.2 mm.

[0188] Such a profile of the downstream zone 442 of the internal ring sector 13 makes it possible to ensure continuity of pressure.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] In one embodiment, axis A may be the main axis of a turbomachine.

[0195] Figure 5 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.

[0196] Figure 6 represents a portion of the turbomachine visible in Figure 5, and illustrates that the latter can be provided with seals conforming to those described above.

[0197] In the embodiment shown, the turbomachine portion has three seals: a front inner seal 62 (“FIS”), a front outer seal 63 (“FOS”) and a first seal downstream of the high pressure compressor 61 (“CDP”).

[0198] 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 the person skilled in the art will be able to identify a front outer seal 63 (“FOS”), a front inner seal 62 (“FOS”) and a first seal downstream of a high pressure compressor 61 (“CDP”) in other geometries of the cooling circuit.

[0199] Figure 6 shows a diagram of a cooling circuit of a turbomachine.

[0200] In the embodiment shown, air is taken downstream of the last compressor disc 401 and also below the combustion chamber 5.

[0201] 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.

[0202] 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.

[0203] The air taken from below the combustion chamber can, for example, be taken through an air inlet, opening into a housing between the front outer seal 63 and the front inner seal 62.

[0204] In Figure 6, these two joints respectively delimit the inlet and the outlet of such a housing.

[0205] 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.

[0206] The seal 63 delimits the outlet of the air intake housing, and limits the flow of air reaching the purge circuit 81.

[0207] For example, seal 62 may be located under the air intake mouth, while seal 63 may be located under the first distributor of the high pressure turbine 701.

[0208] In Figure 6, the purge circuit opens between the high pressure distributor 701 and the first high pressure rotor blade 702.

[0209] 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.

[0210] Figure 6 shows a turbine for which the three particular seals 61, 62, 63 are as described above, but it does not depart from the scope of the invention if only one of these seals conforms to what is described above.

[0211] 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.

[0212] In one embodiment, which is the one shown, the surface 500 facing the seal comprises a groove filled with a varnish 51.

[0213] 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.

[0214] Furthermore, the varnish 51 may be transparent, which then allows even easier monitoring 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.

[0215] 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.

[0216] 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.

[0217] In Figure 6, the air flow through the seals is shown by arrows, and the axis A of the turbomachine is also present.

[0218] 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 a mode alternatively, the air can also exit the cooling circuit through the purge outlet 81, after passing through the front outer seal 62 and rear outer seal 63.

[0219] 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.

[0220] 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.

[0221] 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 (100) configured to ensure a predefined clearance (j) between said seal and an external surface (500) of a rotor rotatably mounted around an axis A 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 an internal ring sector (13) connected to an external ring sector (11) by a return member (12), the sealing seal being characterized in that the internal surface (S in t) of each inner ring sector (13) comprises at least one row of patterns hollowed out from the inner surface (S in t) internal ring sectors (13), each of the patterns having an elongated shape extending in a direction oblique to the axial direction (D A) and being separated from another pattern by an unhollowed portion (41, 42, 43) of the internal surface (Sint).

2. Seal (100) according to claim 1, in which each pattern of the first row of patterns (31) has a planar downstream pattern 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 (H 2) of the downstream pattern zone (312).

3. A seal (100) according to claim 2, wherein the upstream pattern area (311) of each pattern of the first row of patterns (31) has a rounded shape.

4. A seal (100) according to claim 1 to 3, wherein each inner surface (S int) of the inner ring sectors (13) comprises a first and a second row of patterns (31, 32) each of the rows comprising a plurality of patterns distributed in the circumferential direction.

5. A seal (100) according to claim 4, wherein the patterns of the first row of patterns (31) have a depth (H2) greater than or equal to the depth (H5) of the patterns (32) of the second row of patterns.

6. A seal (100) according to any one of claims 4 to 5, wherein each pattern of the second row of patterns (32) has a downstream pattern zone (322) of planar constant depth (H 5) and non-zero and an upstream pattern zone (321) in which the depth of the pattern varies increasingly from the surface internal (S int ) of the internal ring sector (13) while remaining less than the constant depth (H 5) of the downstream pattern zone (322).

7. A seal (100) according to any one of claims 4 to 10. 6, wherein the patterns of the second row of patterns (32) are offset in the circumferential direction relative to the patterns of the first row of patterns (31) by a distance of between 0.25 times the width of a pattern and 0.75 times the width of a pattern.

8. A seal (100) according to any one of claims 1 to 5. 7, in which the patterns have an angle of inclination (a) relative to the axial direction (D A ), this angle of inclination (a) being greater than or equal to 30°.

9. A seal (100) according to any one of claims 1 to 10. 8, wherein the outer ring sectors (11) form an outer shell and the inner ring sectors (13) have circumferential ends arranged end-to-end in the circumferential direction around the axis A and wherein each circumferential end of an inner ring sector (13) has an angle of inclination ( ) relative to the circumferential direction (D c ) between 30° and 90°.

10. A seal (100) according to any one of claims 1 to 10. 9, comprising between 8 and 12 joint sectors.

11. A seal (100) according to any one of claims 1 to 12. 10, further comprising a secondary sealing member (14) arranged radially above the inner ring sector (13) so as to prevent air from axially passing through the seal radially above the inner ring sector (13).

12. An aeronautical turbomachine comprising at least one seal according to any one of claims 1 to 11.

13. An aeronautical turbomachine according to claim 12, comprising a circuit for conveying cooling air to a high-pressure rotor disk, the cooling air conveying circuit comprising at least one seal according to any one of claims 1 to 11, said cooling air conveying circuit comprising an inlet taking air (401) downstream of the last disk of the high-pressure compressor (4), an inlet taking air radially under the combustion chamber (5) and an air outlet opening into a cooling housing of the high-pressure rotor disk and the at least one seal being arranged at one of the positions below: - downstream of the inlet taking air (401) from the high pressure compressor, radially below the last rectifier of the high pressure compressor; - radially below a cooling air injector in fluid communication with the inlet taking air radially below the combustion chamber (5); - radially between the injector and the foot of the high pressure distributor (701) and arranged so as to prevent leakage of air intended to cool the high pressure rotor.

14. Aeronautical turbomachine according to claim 13, in which the seal is arranged downstream of the air intake (401) of the high pressure compressor, radially under the last rectifier of the high pressure compressor and the surface (500) opposite said seal (100) comprises a groove (51) filled with a transparent varnish.

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