FR3146938A1 - Stator assembly for an aircraft turbomachine - Google Patents

Abstract

The invention relates to a seal (700) for an aircraft turbomachine comprising a plurality of seal sectors distributed circumferentially around a longitudinal axis (X), each seal sector comprising a radially outer annular wall sector (710) and a radially inner annular wall sector (712) connected to each other by at least one elastically deformable member, characterized in that the radially outer annular wall sectors form a monolithic outer shell and the radially inner annular wall sectors are arranged circumferentially end-to-end and in that each radially inner annular wall sector (714) comprises a housing (724) formed in the thickness of the inner sector (714) and opening radially onto the radially inner surface of the radially inner annular wall sector, this housing (724) having upstream (724a) and downstream (724a) faces and Circumferential faces (7244) hollowed out in the thickness of the radially internal wall sector (714). Abstract figure: Figure 37

Description

Stator assembly for an aircraft turbomachine

The present disclosure relates to an annular seal, such as a hydrostatic annular seal. The present document also relates to an assembly comprising such a seal as well as a turbine or turbomachine comprising such a seal.

There schematically represents a turbomachine 1 with a double flow of longitudinal axis X. The turbomachine 1 generally comprises, from upstream AM to downstream AV according to the direction of flow of the gases within the turbomachine 1, a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, a low-pressure turbine 7 and an exhaust system downstream of the turbomachine 1. The gas flow, in particular air, entering upstream of the turbomachine 1 first circulates through the fan 2 then divides, on the one hand, into an annular circulation vein called the primary vein 8, and on the other hand, into an annular circulation vein called the secondary vein 9 surrounding the primary vein 8. The low-pressure compressor 3, the high-pressure compressor 4, the combustion chamber 5, the high-pressure turbine 6 and the low-pressure turbine 7 are arranged in the primary vein 8.

In this document, the terms “longitudinal”, “radial” and “circumferential” are defined relative to the longitudinal axis X of the turbomachine 1, the longitudinal axis X coinciding with the axis of rotation of the low-pressure and high-pressure rotors of the turbomachine 1. The terms “inner” and “outer”, as well as “internal” and “external”, are then defined in the radial direction relative to the longitudinal axis X. The terms, upstream and downstream are defined relative to the general direction of flow of the gases in the turbomachine along the longitudinal axis X around which the turbomachine extends.

Reference is now made to Figure 2A schematically representing a partial view of a low-pressure turbine 7 with a longitudinal axis which comprises an alternation of annular rows of moving blades 9 arranged longitudinally in alternation with annular rows of stator blades 10. In the , only two annular rows of rotor blades 9 and one annular row of stator blades 10 are shown. The annular rows of rotor blades 9 or moving blades 9 are connected to each other by a cylindrical shell 11.

Each of the annular rows of stator blades 10 comprises a radially inner annular platform 12 and a radially outer annular platform (not shown) between which a plurality of blades 13 extend. The radially outer annular platform is fixed to a casing of the turbine.

The management of the seal between the end of the stator blades 10 and the shell 11 of the rotor is important to limit gas leaks between the rotor and the stator 10 and to control the pressure and temperature conditions on either side of said seal and also radially below the seal. For this purpose, it is known to provide a radial annular partition 14 extending from said radially internal annular platform towards the inside, and carrying at one end a sealing member 15 intended to maintain in operation a small clearance with the corresponding shell of the rotor.

For this purpose and as shown in FIGS. 2A and 2B, the annular row of stator blades 10 carries an annular clearance-control seal 15 arranged radially inside the annular row of stator blades 10 and radially outside the cylindrical shroud 11, the annular clearance-control seal 22 cooperating in a contactless seal with the cylindrical shroud 11 in order to limit circulation from upstream of the annular row of stator blades 10 to downstream in the annular space between the seal 15 and the cylindrical shroud 11.

In particular, such a clearance control seal 15 operates with a low and controlled annular clearance between the latter and the shell 11 when the turbine is in operation. Furthermore, this type of seal aims to achieve an adaptation of the clearance in operation. The use of the hydrostatic seal 15 then offers the advantage of limiting the leakage flow at the level of the seal, and thus makes it possible to improve the performance of the turbomachine and to reduce the requirements in terms of thermal and mechanical stresses when sizing the various components of the turbine 7.

As shown in FIG. 2B, the hydrostatic annular seal 15 may be formed of two concentric annular walls 16, 17, and a plurality of elastically deformable members arranged circumferentially next to each other and extending between the two walls 16, 17 and including in particular elastically deformable blades 18 extending circumferentially. For example, document WO 2009/148787 describes such a seal. This configuration makes it possible to improve control of the radial deformation of the seal 15, and therefore control of the clearance between the seal 15 and the ferrule 11 cooperating with the sealing gasket 15 so as to limit the passage of air.

The designer seeks to implement a low stiffness, synonymous with a high self-adaptive capacity of the seal and therefore better performance. To do this, the designer must find solutions to associate this low stiffness with a low radially internal wall sector mass. Indeed, the root of the stiffness to mass ratio defines the resonance frequency of the structure. This resonance frequency must be higher than the rotation frequency of the rotor.

This document aims to provide a simple, reliable and economical solution to the above problem.

Summary

There is thus proposed an annular seal, a sealing gasket for an aircraft turbomachine comprising a plurality of sealing gasket sectors distributed circumferentially around a longitudinal axis, each sealing gasket sector comprising a radially external annular wall sector and a radially internal annular wall sector connected to each other by at least one elastically deformable member, characterized in that the radially external annular wall sectors form a monolithic external shell and the radially internal annular wall sectors are arranged circumferentially end-to-end and in that each radially internal annular wall sector comprises a housing formed in the thickness of the internal sector and opening radially onto the radially internal surface of the radially internal annular wall sector, this housing having upstream and downstream faces and circumferential faces hollowed out in the thickness of the radially internal wall sector.

The formation of a housing in the inner face of each radially inner annular wall sector makes it possible to reduce the mass of each radially inner annular wall sector and consequently that of the hydrostatic seal. Furthermore, the stiffness of the radially inner annular wall sector is marginally degraded since the housing is formed in the thickness of each radially inner annular wall sector.

The housing thus produced does not open circumferentially or longitudinally since the facing faces are formed in the thickness of the radially internal annular wall sector.

The housing will be able to cover 60 to 90% of its circumferential length.

The length of the housing may be 10 to 40% of the axial length of the skate.

Each housing may extend circumferentially by a distance less than 10 to 40% of the circumferential extent of the radially inner annular wall sector.

Each housing may extend longitudinally for a distance less than 60% of the longitudinal extent of the radially inner annular wall sector.

Each housing may have a depth of at most 60% of the maximum radial dimension of the pad and at least 10%.

Each housing may be substantially circumferentially centered on the circumferential extent of the radially inner annular wall sector.

The housing may include a back face.

The circumferential faces and/or the upstream and downstream faces and/or the bottom face of each radially internal wall sector are substantially flat, and preferably substantially parallel two by two so as to form a parallelepiped.

The housing may be formed in a recess in the radially inner surface of the radially inner annular wall sector, the recess extending from one circumferential end to the other of the radially inner annular wall sector and longitudinally having a concave curved shape.

The radially inner surface of each radially inner annular wall sector may comprise a first substantially cylindrical surface portion, a second surface portion forming the recess, a third substantially cylindrical surface portion and preferably a fourth frustoconical surface portion with a section increasing downstream.

Each radially inner annular wall sector may comprise a first circumferential edge and an opposing second circumferential edge each comprising a slot and in which a tab is mounted partly in a slot of a first circumferential edge of a radially inner annular wall sector and in an opposing circumferential slot of a second circumferential edge of an adjacent radially inner annular wall sector.

This document also relates to an assembly comprising a cylindrical rotor shroud intended to be driven in rotation about the longitudinal axis and a distributor which has a crown of stator blades, the distributor comprising a foot (403) at the radially internal end of the distributor, a seal being mounted on the foot (403) of the distributor, and the seal cooperating in a contactless manner with the cylindrical rotor shroud of the turbomachine arranged radially under the distributor.

Also concerned is a turbine for an aircraft turbomachine, the turbine comprising a casing, an assembly and a rotor which comprises a cylindrical shroud driven in rotation about the longitudinal axis and, the distributor being mounted in the casing and the cylindrical shroud being arranged radially under the distributor.

This document also relates to a turbomachine, such as an aircraft turbojet or turboprop, comprising an assembly or a turbine.

Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the attached drawings, in which:

schematically illustrates a cross-sectional view of an example of a turbomachine;

schematically illustrates a partial view of a portion of a turbine, for example low pressure, Figure 2B being an enlargement of the seal illustrated in Figure 2A;

schematically illustrates an annular sealing gasket;

schematically illustrates a portion of an annular row of stator blades and a seal according to this document;

is a larger scale view of the gasket of the ;

And schematically illustrate the sealing principle of the seal according to this document;

schematically illustrates a first seal according to this document;

schematically illustrates a second seal according to this document;

has schematically illustrate a third type of seal according to this document as well as variations thereof;

has schematically illustrate alternative embodiments of the connecting tabs between a radially external annular wall and the radially internal annular walls for a seal;

is a three-dimensional schematic view of a sector of an annular row of stator or distributor blades according to this document;

is a schematic perspective view of part of a hydrostatic annular seal;

is a schematic perspective view of the legs of a hydrostatic annular seal;

And are schematic perspective views of the radial sliding means between the hydrostatic annular seal and the annular row of stator blades;

is a sectional view of an assembly according to this document;

has are schematic perspective views of an assembly comprising a hydrostatic annular seal according to this document;

And including schematic perspective views of an assembly according to the present document and comprising a hydrostatic annular seal connected by form cooperation with radial sliding connection means on an annular row of stator blades;

is a schematic perspective view of a circumferential edge of an annular seal as described herein;

is a schematic illustration of an annular seal according to this document, the annular seal having a housing on its radially inner face;

schematically illustrates a partial view of an exemplary assembly according to this document, this assembly comprising an annular seal;

schematically illustrates an enlarged partial view of an example assembly according to the ;

schematically illustrates an enlarged partial view of another example of an assembly according to the ;

schematically illustrates respectively a partial view of an exemplary assembly according to the present document, and two enlarged partial views of the exemplary assembly in two different configurations;

schematically illustrates a partial view of an example of a hydrostatic annular seal;

schematically illustrates a partial sectional view of an exemplary assembly according to this document;

schematically illustrates a partial sectional view of another example assembly according to this document;

schematically illustrates a partial sectional view of another example assembly according to this document;

schematically illustrates a partial sectional view of another example assembly according to this document.

This document relates to an annular sealing gasket such as a hydrostatic annular sealing gasket used in a turbomachine. It includes in particular different embodiments and integration forms of such a hydrostatic annular sealing gasket.

Reference is made to the schematically representing a partial view of a hydrostatic annular seal 51 according to the present document. Preferably, this hydrostatic annular seal 51 is integrated into an assembly 52 for a turbomachine with a longitudinal axis X. Such an assembly is implemented in a turbine, in particular a low-pressure turbine, of a turbomachine. The present document also relates to any type of turbomachine comprising such a turbine, for example a turboprop or a turbojet for an aircraft.

The assembly 52 comprises a cylindrical shell 53 intended to be driven in rotation about the longitudinal axis X and an annular row of stator blades. The assembly may also comprise two annular rows of moving blades arranged longitudinally on either side of the annular row of stator blades 54 and connected to each other by the cylindrical shell 53. The annular row of stator blades 54 carries the hydrostatic annular seal 51. This hydrostatic annular seal 51 is arranged radially inside the annular row of stator blades 54 and radially outside the cylindrical shell 53, the hydrostatic annular seal 51 cooperating in a contactless seal with the cylindrical shell 53.

The hydrostatic annular seal 51 preferably comprises a radially external annular wall 55, a radially internal annular wall 56 and a plurality of elastically deformable members or elements 57, in particular distributed circumferentially around the longitudinal axis X. The hydrostatic annular seal 51 can deform radially thanks to the flexibility offered by the elastically deformable member 57 connecting together the radially internal annular wall 56 and the radially external annular wall 55. The radially internal 56 and external 55 annular walls and the elastically deformable element 57 are in particular dimensioned to control the radial deformation of the hydrostatic annular seal 51, and therefore control a clearance J2 between the hydrostatic annular seal 51 and the cylindrical shell 53.

The seal may comprise a plurality of seal sectors distributed circumferentially around the longitudinal axis, each seal sector comprising a radially internal annular wall sector 56 and a radially external annular wall sector 55 connected to each other by an elastically deformable member 57. The radially external annular wall sectors may form a monolithic external shell, i.e. a single piece, and the radially internal annular wall sectors are distinct and arranged circumferentially end to end.

A turbine is a system that expands air, starting from a high pressure upstream to a low pressure downstream. It is necessary for there to be a maximum of air that passes through the turbine and does not escape from the vein. A layer of air coming from the annular cavity located upstream of the seal 51 passes between the cylindrical shell 53 and the seal 51 whose differences in radial dimensions form the clearance J2. By maintaining a low radial clearance, the hydrostatic annular seal 51 thus provides a seal. It is the pressure differential between the annular cavity upstream of the hydrostatic annular seal 51 and the annular cavity immediately downstream of this hydrostatic annular seal 51 which controls the resultant of the radial pressure forces applied to the radially internal annular wall 56 of the hydrostatic seal 51.

The hydrostatic annular seal 51 comprises an internal surface 59 arranged radially opposite the cylindrical shell 53. This internal surface 59 comprises a first substantially cylindrical surface portion 60, a second concave curved surface portion 61 with a concavity curved radially outwards so as to form an annular cavity opposite the cylindrical shell 53, a third substantially cylindrical surface portion 62 and a fourth truncated surface portion 63 with a section increasing downstream. There is a clearance j1 between the first surface portion 60 and the cylindrical shell 53, and a clearance j2 between the third surface portion 62 and the cylindrical shell 53. The clearances j1 and j2 are such that the clearance j1 is greater than j2. This difference in clearances between j1 and j2 generates a restriction. This restriction allows the air to be accelerated and causes static pressure to be lost in the event of a high clearance j1 (>0.6 mm for example). The hydrostatic annular seal 51 deforms under the resultant of the mechanical forces exerted on the internal surface 59 and the external surface 63 of the sectorized pad 58. This specific configuration allows a low clearance to be maintained and therefore efficient sealing, without risking contact between the sectorized pad 58 and the ferrule 53.

The annular row of stator blades 54 comprises a radial annular partition 64 carrying the hydrostatic annular seal 51. The hydrostatic annular seal 51 may comprise radial sliding means 65 in the direction of the annular row of stator blades 54. The radially external annular wall 55 is connected to an annular part 71 comprising an upstream annular tab 66 and a downstream annular tab 67 each comprising longitudinally facing orifices 68 in which pins 69 are mounted. The external annular wall 55 and the annular part 71 may be formed from a single piece. The pins 69 are mounted shrink-fitted in the orifices 68 of one of the upstream 66 and downstream 67 annular tabs only so as to allow the insertion of the upstream 66 and downstream 67 annular tabs into the other. Preferably, the shrink-fitting is carried out on the upstream annular tab 66. The radial annular partition 64 of the annular row of stator blades 54 comprises a plurality of preferably oblong openings 70 in which an intermediate portion of the pins 69 are mounted. Alternatively, the openings may be rectangular. This assembly allows a degree of freedom in the radial direction of the hydrostatic annular seal 51 relative to the annular row of stator blades 54. Other means of radial movement could be envisaged. The radial sliding of the hydrostatic annular seal 51 may be carried out as in FIGS. 21 to 26, but also as in FIGS. 27 to 33.

Thus, a degree of freedom in the radial direction is left to the hydrostatic annular seal 51 when the turbomachine is in operation. Indeed, under the effect of heat, expansions of the annular row of stator blades 54 opposite the annular part 71 occur. The U-shape produced by the connection between the upstream annular tab 66 and the downstream annular tab 67 makes it easier to mount and guide the seal radially by sliding on the annular partition 64. This U-shape therefore expands radially under the effect of the expansion and this U-shape guarantees that there will be no thrust radially outwards. Thus, the hydrostatic annular seal 51 is guided and undergoes little deformation by temperature differential with the adjacent/neighboring components both in the radial direction, and in the circumferential or even longitudinal direction.

In order for there to be the pressure differential described above between the upstream cavity and the downstream cavity of the turbine, it is necessary to produce a secondary seal 72. This secondary seal 72 prevents there from being a leak between the radially internal annular wall 56 and the radially external annular wall 55 and that the air passes only between the cylindrical shell 53 and the sectors of the radially internal annular wall 56.

For this purpose, reference is now made to Figures 4 to 7.

Figures 4 and 5 show the hydrostatic annular seal 51 provided with the secondary seal 72 and fixed to the annular row of stator blades 54. This hydrostatic annular seal 51 is intended to be arranged longitudinally between two annular rows of rotor blades 73 arranged on either side of an annular row of stator blades 54. As described above, the hydrostatic annular seal 51 comprises a radially internal annular wall 56, a radially external annular wall 55 connected to each other by the elastically deformable members 57. An annular flange is arranged opposite the upstream faces 74 of the elastically deformable members 57. This flange is carried by the radially external annular wall 55. There is an annular clearance between a radially internal end 76 of the crown 75 and the radially internal annular wall 56. This annular clearance is sealed by the secondary seal 72 which we will describe in more detail.

As illustrated in FIGS. 4 to 6, a first annular row of first sheet metal sectors 77 is arranged circumferentially end to end and applied to an upstream face 78 of the crown 75. A second annular row of second sheet metal sectors 79 is applied to upstream faces 80 of the first annular row of first sheet metal sectors 77. The sheet metal sectors 77, 79 have a thickness of between 0.1 and 0.6 mm. The second sheet metal sectors 79 may be arranged circumferentially by being offset relative to the first sheet metal sectors 77 so that a second sheet metal sector 79 is arranged longitudinally opposite two circumferentially adjacent first sheet metal sectors. The inner edges 81 of the second sheet metal sectors 79 are longitudinally aligned with the inner edges 82 of the first sheet metal sectors 77. The outer edges 83 of the second sheet metal sectors 79 are longitudinally aligned with the outer edges 84 of the first sheet metal sectors 77. The circumferential edges 85, 86 of the first sheet metal sectors 77 are misaligned with the circumferential edges 87, 88 of the second sheet metal sectors 79. The misalignment of the circumferential edges 85, 86, 87, 88 of the first 77 and second sheet metal sectors 79 makes it possible to avoid a leak linked to the annular clearance.

More specifically, as illustrated in , the radially internal ends 89 of the first sheet metal sectors 77 bear on a radial face 90 of the radially internal annular wall 56. The flange 75 comprises an internal annular rim 91a which extends upstream. An upstream face 92 of the crown 75 is formed at the upstream end of the internal annular rim 91a of the flange 75. The first annular row of the first sheet metal sectors 77 is arranged circumferentially end to end and applied to the upstream face 92 of the crown 75. The material of the first sheet metal sectors and that of the flange is determined so as to facilitate sliding between these two parts.

The flange 75 also includes a downstream extending annular flange 91b formed at its radially outer end. As can be seen in the , the annular rim 91b radially covers the upstream ends of the radially external annular wall sectors.

As illustrated in FIGS. 4 to 7, the sheet metal sectors 77, 79 are fixed to the crown 75 by fixing elements 93 passing through openings 94 on the sheet metal sectors 77, 79. These fixing elements 93 fix the first 77 and second sheet metal sectors 79 together to the crown 75, itself carried by the radially external annular wall 66. The fixing elements may be pins. The openings 94 are such that there is play and that the sheet metal sectors 77, 79 are able to move slightly.

We now refer to the which represents a hydrostatic annular seal 150 intended to provide sealing between an annular stator row to which it is connected and a cylindrical shell as described with reference to the . As illustrated in the , the annular seal 150 which is of a known type comprises an internal annular wall 151 formed of sectors 152 arranged circumferentially end to end. It also comprises an external annular wall 153 from which can extend at least one annular tab or wall 154 comprising at least one orifice 155 for the insertion of an axis preferably materialized by a pin, or by the smooth barrel of a screw, or a spacer as an alternative, intended to cooperate with an oblong opening of a radial annular partition carried by the internal annular platform of the annular row of stator blades.

Each radially internal annular wall sector 152 is connected to the external annular wall 153 by an elastically deformable member 156. Thus, each radially internal annular wall sector is associated with an elastically deformable member 156.

Each elastically deformable member 156 comprises two elastic strips 159 extending circumferentially and parallel to each other. First ends of the strips 159 are connected to a first radial tab 158 carried by a radially internal annular wall sector and second ends of the strips 159 are connected to a second radial tab 157 carried by the radially external annular wall 153. If this type of embodiment proves effective, it does not make it possible to achieve the best compromise between radial flexibility and resistance to torsion for a given thickness of strips as mentioned with reference to the prior art at the beginning of the description.

Thus, a hydrostatic annular seal 100 is provided formed from a plurality of circumferentially distributed sealing gasket sectors, only one being shown in . Each seal sector 102a, 102b comprises a radially outer annular wall sector 106a, 106b and a radially inner annular wall sector 110a, 110b connected to each other by an elastically deformable member 105a, 105b, in which the circumferentially adjacent pairwise seal sectors 102a, 102b have their respective elastically deformable member 105a, 105b monolithically produced in a common deformable elastic member 105, the common deformable elastic member 105 connecting together two circumferentially adjacent radially inner annular wall sectors 110a, 110b of seal sector and in which the radially outer annular wall sectors 106a, 106b of the seal sectors form a monolithic external ferrule 106.

Thus, each common elastic member 105 is elastically connected to at least two sectors of radially internal annular walls 110a, 110b, here exactly two, which are circumferentially adjacent and to two sectors 106a, 106b of radially external annular wall 106. The sectors of radially internal annular walls 110a, 110b successively form the radially internal annular wall of the hydrostatic annular seal 100. In the embodiment shown in , each elastically deformable member 105 is connected to two circumferentially adjacent internal sectors 110a, 110b, one 110a being named as a primary sector and the other 110b being named secondary sector.

It is observed that each common elastic member 105 comprises at least one first elastically deformable circumferential blade 112a, 112b and at least one second elastically deformable circumferential blade 114a, 114b connected by first circumferential ends facing each other to the external annular wall and of which second ends 122 circumferentially opposite one another relative to the first ends are each connected to the primary sector 110a and to the secondary sector 110b. Said first end 116 of said at least one first blade 112a, 112b and said first end 116 of said at least one second blade 114a, 114b are arranged in a circumferential screw.

On the , it is observed that said at least one first blade 112a, 112b and said at least one second blade 114a, 114b comprise two blades which are radially spaced from one another. The first blades 112a, 112b and/or the second blades 114a, 114b may be substantially parallel to one another as shown in the . The first blades 112a, 112b and/or the second blades 114a, 114b may further form an angle between them. Among the first blades 112a, 112b, a first blade 112b is a first inner blade 112b and the other 112a is a first outer blade. Among the second blades 112a, 112b, a second blade 112b is a second inner blade and the other 112a is a second outer blade.

The first ends 116 of the first and second elastic blades may be connected, as shown in , to the same first leg 118 which can extend substantially radially. The first internal blade 111b and/or the second internal blade 114b can be connected to the radially internal end of the first leg 118. The first external blade 112a and/or the second external blade 114a can be connected in the vicinity of the radially external end of the first leg 118, this radially external end of the first leg 118 being connected to the radially external annular wall.

The radially internal end of the first leg 118 is devoid of direct connection to one of the two circumferentially adjacent primary 110a and secondary 110b sectors, the connection of the first leg 118 with the sectors 110a, 110b being made indirectly by the first 112a, 112b and second blades 114a, 114b and the second legs 120a, 12ab, the latter being described in the following paragraphs.

In the realization of the , the legs are sized so as not to be deformable, the deformation taking place at the level of the blades.

The second ends 122 of the first and second elastic blades may be connected, as shown in , to a second leg 120a, 120b which can extend substantially radially. It is observed that there are two second legs 120a, 120b which are arranged on either side circumferentially of the first leg 118 and which can be positioned circumferentially in a manner substantially symmetrical to each other relative to the position of the first leg 118. A second leg called the second primary leg 120a is connected to the second ends of the first blades 112a, 112b and a second leg called the second secondary leg 120b is connected to the second ends of the second blades 114a, 114b.

According to the realization represented in , the common elastically deformable member thus has a first circumferential end radial tab 120a connected to a circumferential end of the internal annular wall sector 110a of a first seal sector 102a and a second circumferential end radial tab 120b connected to a circumferential end of the internal annular wall sector 110b of a second seal sector 102b, each circumferential end radial tab 120a, 120b being connected to a common radial tab 118 by a first blade 112a, 112b and a second blade 114a, 114b which each extend circumferentially to connect each circumferential end radial tab 120a, 120b to a common radial tab 118.

The term “primary” and the term “secondary” only serve to distinguish between the two second legs 120a, 120b and their connection to the primary 110a and secondary 110b sectors.

The first external blade 112a and/or the second external blade 114a may be connected to the radially external end of the second primary 120a and secondary 120b legs. The first internal blade 112b and/or the second internal blade 114b may be connected in the vicinity of the radially internal end of a second leg 120a, 120b, this radially internal end of a second leg 120a, 120b being connected to a shoe 110a, 110b. More precisely, the radially internal end of the second primary leg 120a is connected to the primary sector 110a and for example in the vicinity of a circumferential end thereof. The radially internal end of the second secondary leg 120b is connected to the secondary shoe 110b and for example in the vicinity of a circumferential end thereof. Said two ends of the primary 110a and secondary 110b sectors are opposite their ends which are circumferentially opposite.

Compared to the , the embodiment mentioned above makes it possible to eliminate a connecting tab for each pair of primary 110a and secondary 110b sectors, which makes it possible to lighten the structure of the hydrostatic annular seal 100. A significant gain in size is also obtained in the circumferential direction. At constant stiffness compared to the prior art, it is thus possible to use a greater thickness of blades, thus making it possible to limit torsion. Thus, for each pair of primary 110a and secondary 110b sectors, it is necessary to have only three tabs instead of four as in the .

The annular seal 100 could comprise means allowing radial sliding of the hydrostatic annular seal relative to the radial annular partition of the annular row of stator blades. These means could be, for example, of the type described with reference to FIGS. 21 to 25 or with reference to FIGS. 27 to 33.

Reference is now made to Figures 10 to 20.

Figures 10 to 16 schematically illustrate a third hydrostatic annular seal 201 as well as variations thereof.

There represents a hydrostatic annular seal 201 comprising a radially internal annular wall 202, an elastically deformable member 203 and a radially external annular wall 204. The radially internal annular wall 202 is formed of a plurality of sectorized pads 205. The sectorized pad 205 represented is connected to the radially external annular wall 204 by the elastically deformable member 203. This elastically deformable member 203 comprises an internal tab 206 and an external tab 207. Each tab 206,207 is substantially planar. The inner tab 206 has a radially inner end 208 to which said sectored pad 205 is fixed. The outer tab 207 has a radially outer end 209 to which the radially outer annular wall 204 is fixed. The inner tab 206 has a radially outer end 210 connected to a radially inner end 211 of the outer tab 207 by a connecting wall 215. In the embodiment of the , the inner leg 206 and the outer leg 207 extend radially such that the radially inner end 211 of the outer leg 207 is arranged radially inside the radially outer end 210 of the inner leg 206.

The hydrostatic annular seal 201 shown in comprises an elastically deformable member 203 formed of several elastically deformable members. It thus comprises a first elastically deformable member 212 and a second elastically deformable member 213. The first 212 and second 213 elastically deformable members are arranged so that the internal tab 206, respectively the external tab 207, of the first member 212 is axially adjacent to the external tab 207, respectively the internal tab 206, of the second member 212.

The hydrostatic annular seal 201 shown in comprises an elastically deformable member 203 formed of three elastically deformable members, a first member 212, a second member 213 and a third member 214. The first 212 and second 213 members are arranged so that the internal leg 206, respectively the external leg 207, of the first member 212 is axially adjacent to the external leg 207, respectively the internal leg 206, of the second member 213. The third member 214 is arranged so that its external leg 207, respectively its internal leg 206, is axially adjacent to the internal leg 206, respectively the external leg 207, of the second member 212.

The outer leg 207 may be inclined relative to a tangent to the radially outer annular wall 204 at the connection point between the outer leg 207 and the radially outer annular wall 204. Similarly, the inner leg 206 may be inclined relative to a tangent to the radially inner annular wall 202 at the connection point between the inner leg 206 and the radially inner annular wall 202. This angle may be between 10° and 150°. It is thus understood that the inner leg 206 and the outer leg 207 may have different inclinations as clearly appears in the . Other embodiments are of course possible. The inclination of the legs 207, 206 relative to the radial direction makes it possible to restrict the movement of the elastically deformable member in the longitudinal direction.

Each connecting wall 215 may comprise a thickness, defined by the radial dimension of the connecting wall 215, of between 0.5 and 10 mm and/or a width, defined by the longitudinal dimension of the connecting wall 215, of between 2 and 30 mm.

• Une largeur selon la direction longitudinale comprise entre 2 et 30 mm,
• Une dimension selon sa direction d’extension entre ses extrémités radialement interne et externe comprise entre 3 et 60 mm,
• Une dimension perpendiculaire à la direction d’extension de la patte comprise entre 0.5 et 10 mm.

Each leg 206, 207 may comprise at least one of the following parameters:

• A width in the longitudinal direction between 2 and 30 mm,
• A dimension according to its direction of extension between its radially internal and external ends between 3 and 60 mm,
• A dimension perpendicular to the direction of extension of the leg between 0.5 and 10 mm.

As illustrated in the , the hydrostatic annular seal 201 comprises first 212 and second 213 members. The connecting wall 215 makes it possible to restrict the upstream/downstream tilting movements due to its resistance to torsion. The internal and external legs 206, 207 which are also deformable allow a predominantly radial movement by bending of the elastically deformable member. The inclination of the legs 206 and 207 relative to the internal 202 and external 204 annular wall makes it possible to limit the movement of the shoe 205 along the longitudinal axis

As illustrated in the , the hydrostatic annular seal 201 may comprise a first 212 and a second 213 elastically deformable members. The connecting wall 215 of the first member 212 comprises a radially internal surface formed successively by a concave surface 216 then a convex surface 217. The connecting wall 215 of the second member 213 comprises a radially internal surface formed successively by a convex surface 217 then a concave surface 216.

The hydrostatic annular seal 201 shown in comprises an elastically deformable member 203 comprising a first 212 and a second 213 member. The connection between the radially external end 210 of the internal leg 206 and the connecting wall 215 of each member is at a right angle. Similarly, the connection between the radially internal end 211 of the external leg 207 and the connecting wall 215 of each member is also at a right angle. illustrates the oblique inclination of organs 212, 213.

Figures 17 to 20 schematically illustrate alternative embodiments of the connecting tabs of the connecting walls 215 to the radially internal annular walls 202 and external 204 for a hydrostatic annular seal 201. Only an external tab 207 is illustrated but the description also applies to an internal tab 206.

There represents a leg 207 with a substantially constant section between its internal and external ends.

There illustrates a leg 207 with a section which evolves radially and which increases in the particular case of the The general shape here is triangular.

There represents a leg 207 having a circumferential surface facing the other leg which is concave and an opposite circumferential surface which is substantially planar.

There also represents a leg 207 having concave and flat circumferential surfaces as in the . However, in this embodiment, the radially inner end of the tab has a smaller dimension than the radially outer end.

The hydrostatic annular seal 201 comprises at least one material or combination of materials from the following list: steel, titanium, aluminum alloy, cobalt-based alloy, nickel-based alloy and/or any composite material.

We now refer to Figures 21 to 26 which concern the radial sliding of a hydrostatic annular seal 300 on an annular partition 305 of an annular row of stator blades.

In reference to the , there is shown a sector 310 of an annular row or crown of stator blades which is here a distributor. Such sectors are arranged circumferentially end to end to form the crown of stator blades. This crown carries a hydrostatic annular seal 300 which is shown in . It could be of any type as described in this description, for example those described with reference to Figures 9 or Figures 10 to 20.

All 310 distributor crown sectors are identical so the following description, which relates to one sector of the , applies to each of the other 310 sectors of the distributor.

In reference to the , the sector comprises an internal platform 312, an external platform 314 and blades 316.

The blades 316 are each connected on the one hand to the internal platform 312 and on the other hand to the external platform 314 so as to extend radially through a primary air stream, which is radially delimited by these platforms 312, 314.

The blades of the sector 310 are circumferentially spaced from each other. The external platform 314 is configured to be fixed on a casing of the turbomachine 1.

The sector 310 comprises a radial partition 305 forming the foot of the distributor 310 and which is connected to the internal platform 312 so as to extend radially inwards from the internal platform 312, towards a cylindrical shell 11 of the rotor, the cylindrical shell being shown in the figure. or even the or the .

The radial partition 305 is configured to cooperate with a hydrostatic annular seal 300 ( ). The hydrostatic annular seal 300 comprises a sectorized radial annular wall 320, formed of a plurality of rapidly internal annular wall sectors arranged circumferentially end to end. The latter are connected by elastically deformable members 322 to a radially external annular wall 325 fixed to the seal support 324 which comprises a radially external annular wall 323 and radially outwardly at least one radial annular tab 326, preferably two radial annular tabs as illustrated in .

In this regard, the shows a circumferential section only of the gasket support 324.

In reference to the , the radial annular legs 326 or flanges are substantially parallel and longitudinally spaced from each other so as to form a U-shaped section defining a space into which the radial partition 305305 of each of the sectors 310310 can be inserted.

The longitudinal distance between the legs 326 is chosen so as to allow adequate longitudinal positioning and maintenance in longitudinal position of the sectors 310, while allowing its mobility by radial sliding of the partition 305 between the legs 326 (see below). In particular, an axial or longitudinal clearance J1, J2 is left during assembly between the legs 326 and the partition 305 to allow this radial movement. The clearance J1 extends between the upstream leg 326 and the partition 305, and the clearance J2 extends between the partition 305 and the downstream leg 326.

Furthermore, the partition 305 is mounted with a radial clearance J3 relative to the bottom of the space defined by the legs 326.

In the embodiment shown in , the radially external annular wall 324 is formed in a single piece with the elastically deformable members 322, with the radially internal annular wall 320 and with at least one of the annular legs 326.

There shows two orifices 328 made respectively in the upstream leg 326 and the downstream leg 326.

The orifices 328 have a common axis A2 and are designed to receive a pin 330 such as that shown in the figure. The pin 330 is a cylindrical part with axis A2 having two shoulders which define an upstream part 332, an intermediate part 334 and a downstream part 336.

The intermediate portion 334 has a diameter smaller than the diameter of the upstream portion 332 and the downstream portion 336. The diameter of the upstream portion is furthermore smaller than that of the downstream portion.

The orifice 328 of the upstream tab 326 of the hydrostatic annular seal 300 is sized to receive the upstream portion 332 of the pin 330 so as to form a tight fit. Similarly, the orifice 328 of the downstream tab 326 of the hydrostatic annular seal 300 is sized to receive the downstream portion 336 of the pin so as to form a tight or sliding fit.

After assembly, the pin 330 is thus carried by the upstream 332 and downstream 436 legs, forming a complete connection with it.

The pin 330 is configured to cooperate with the distributor, in particular with the radial partition 305 of the sector 310.

In reference to the , the partition 310 of each of the sectors comprises for this purpose an opening 338 which has an oblong shape of the groove type extending radially.

In this example, the opening 338 opens radially towards the inside of the crown sector 310. It could not open radially. This would require different geometric arrangements of the pin and different assembly steps than those presented here.

The opening 338 has a width, or circumferential dimension, allowing it to be crossed by the intermediate part 334 of the pin 330, that is to say a width greater than the diameter of the intermediate part 334 of the pin 330.

The width of the opening 338 is also less than the diameter of the upstream part 332 and the downstream part 336 of the pin 330. Thus, in the event of a break in the connection between the pin 330 and the upstream and downstream tabs 326, the partition 305 of the sector 310 forms an axial stop for retaining the pin 330.

The assembly of this stator element includes a pre-insertion of the pin 330 into the upstream and downstream legs 326 by passing the upstream part 332 of the pin 330 through the orifice 328 of the downstream leg 326.

The pin 330 is then fixed to the legs by forced insertion of its upstream part 332 into the orifice 328 of the upstream leg 326 and, simultaneously, of its downstream part 336 into the orifice 328 of the downstream leg 326.

The sector 310 is then moved radially inwards so as to introduce the partition 305 axially between the legs 326 and to insert the intermediate part 334 of the pin 330 into the opening 338 of the partition 305.

These assembly steps result in the configuration illustrated in .

In this configuration, the pin 330 forms on the one hand a circumferential stop for the crown sector 310, preventing a displacement of the hydrostatic annular seal 300 and the crown sector 310 relative to each other in rotation around the axis of the sector 310 and making it possible to center the hydrostatic annular seal 300 relative to this axis A1.

On the other hand, taking into account the respective dimensions of the intermediate part 334 of the pin 330 and 330 of the oblong opening 338, the assembly allows a radial displacement of the hydrostatic annular seal 300 relative to the sector 310.

The stator assembly may include other pins similar to pin 330, each cooperating with partition 305 according to the principles described above.

Of course, these principles can be generalized. For example, each of the sectors 310 of the distributor can cooperate with several pawns similar to pawn 330.

In general, the invention makes it possible to connect the hydrostatic annular seal 300 and the distributor 310 to each other according to a connection defining a radial degree of freedom or radial sliding capable of compensating for differential thermal expansions within the turbine 9.

Finally, the forced mounting of the pins 330 in the orifices 328 of the upstream and downstream legs 326 contributes to the reduction of gas leaks outside the primary vein.

Reference is made to Figures 27 to 33.

The embodiment shown in Figures 27 to 32 of a hydrostatic annular seal 419 is proposed in which a radially external annular wall 401 is fixed by bolting to a seal support 402.

The hydrostatic annular seal 419 thus comprises a radially internal annular wall 420 which is sectorized and a radially external annular wall which is also sectorized 401.

The seal support 402 is mounted to slide radially on the radial annular partition 403 described above with reference to the . The annular seal support 402 comprises an upstream annular tab 404 and a downstream annular tab 405. The upstream annular tab 404 and the downstream annular tab 405 are connected to each other by a base so as to form a U. The radial annular partition 403 comprises oblong openings 406 opening radially inwards.

In a particular embodiment, illustrated in FIGS. 27 to 31, the seal support 402 comprises longitudinal and circumferential projections 415 defining between them radial notches in which are engaged radial tabs 416 formed in radially outward projections from the radially external annular wall sectors 401 of the hydrostatic annular seal. This shape cooperation makes it possible to lock the annular seal in rotation on the seal support 402.

As illustrated in , a sheet metal 414 may be interposed longitudinally between the radial annular partition 403 and the seal support 402. The sheet metal 414 comprises two radial annular branches connected to each other by a substantially cylindrical base. The branches comprise free end portions which are curved radially inwards so as to form a curved portion which cooperates by form connection with a lateral outgrowth of the annular legs 404, 402 of the annular seal support.

Each elastically deformable member 407 may be elastically connected to at least two circumferentially adjacent radially inner annular wall sectors 408a, 408b. In the embodiment shown in FIGS. 28, 29 and 32, each elastically deformable member 407 is connected to two circumferentially adjacent radially inner annular wall sectors, one being referred to as a primary sector and the other being referred to as a secondary sector.

It is observed that each elastically deformable member 407 comprises at least one first elastically deformable circumferential blade 408 and at least one second elastically deformable circumferential blade 409 connected at a first common end to the radially external annular wall 401 and of which second ends circumferentially opposite one another relative to the first common end are each connected to a sector of radially internal annular wall shoe 408a, 408b.

In Figures 28, 29 and 32, it is observed that said at least one first blade 408 and said at least one second blade 409 comprise two blades which are radially spaced from each other. The first blades and/or the second blades may be substantially parallel to each other as shown in Figures 28, 29 and 32. The first blades and/or the second blades may further form an angle between them. Among the first blades, a first blade 408 is a first internal blade 408 and the other is a first external blade 408. Among the second blades, a second blade 409 is a second internal blade 409 and the other is a second external blade 409.

Said first ends of the first and second elastic blades can be connected, as shown in FIGS. 28, 29 and 32, to the same first leg 410 which can extend substantially radially. The first internal blade 408 and/or the second internal blade 409 can be connected to the radially internal end of the first leg 410. The first external blade 408 and/or the second external blade 409 can be connected in the vicinity of the radially external end of the first leg 410, this radially external end of the first leg 410 being connected to the radially external annular wall 401.

The radially inner end of the first leg 410 is devoid of direct connection to one of the two circumferentially adjacent pads, the connection of the first leg 410 with the radially inner annular wall being achieved indirectly by the first and second blades and the second legs, the latter being described in the following paragraphs.

Said second ends of the first and second elastic blades can be connected, as shown in FIGS. 28, 29 and 32, to a second leg 411 which can extend substantially radially. It is observed that there are two second legs 411 which are arranged on either side circumferentially of the first leg 410 and which can be positioned circumferentially in a manner substantially symmetrical to each other relative to the position of the first leg 410. A second leg 411 called the second primary leg 411 is connected to the second ends of the first blades and a second leg 411 called the second secondary leg 411 is connected to the second ends of the second blades.

The term "primary" and the term "secondary" only serve to distinguish between the two second legs and their connection to the corresponding primary or secondary pads.

The first outer blade 408 and/or the second outer blade 409 may be connected to the radially outer end of the second primary and secondary legs. The first inner blade 408 and/or the second inner blade 409 may be connected in the vicinity of the radially inner end of a second leg 411, this radially inner end of a second leg 411 being connected to a pad. More precisely, the radially inner end of the second primary leg 411 is connected to the primary pad and for example in the vicinity of a circumferential end thereof. The radially inner end of the second secondary leg 411 is connected to the secondary pad and for example in the vicinity of a circumferential end thereof. Said two ends of the primary and secondary pads are opposite their ends which are circumferentially opposite.

As illustrated in , a ring or spacer 413 acts as an axis for the free expansion of the joint support 402.

In a particular embodiment illustrated in , the radially outer annular wall 401 is formed by a radial ring 417.

Reference is made to Figures 34 and 35 illustrating a hydrostatic annular seal 501. This hydrostatic annular seal 501 comprises a sectored radially external annular wall 502, a sectored radially internal annular wall 503 and an elastically deformable member 504 arranged between said two internal and external walls.

As illustrated in FIG. 34A, the radially outer annular wall 502 is secured in a seal support 505. Each sector of the radially outer annular wall 502 carries a coupling member 506 circumferentially engaged and radially retained in a circumferential groove of the seal support 505. The coupling member 506 has a dovetail shape extending circumferentially. The seal support 505 comprises an upstream wall 507 extending radially inwards and formed opposite the upstream face of the hydrostatic annular seal 501 so as to participate in the sealing of the elastically deformable member 504. The annular part 505 comprises an upstream annular tab 508 and a downstream annular tab 509. The upstream annular tab 508 and the downstream annular tab 509 form a U capable of sliding radially on a radial annular partition of an annular row of stator blades as illustrated in . The radial annular partition may comprise oblong or rectangular openings opening radially inwards and in which are engaged fixing means passing through the upstream and downstream legs of the seal support 505. The fixing means may comprise pins as described with reference to FIGS. 24 and 25.

Figure 34B illustrates the presence of a locking member for the radially external annular wall sector on the seal support 505. The locking is here achieved by a pin 513 engaged and shrunk through the support and the coupling member 506 of the seal 501.

As illustrated in FIG. 35A, the seal support may be a 360° part which includes a lateral opening 509 opening into the circumferential groove of the seal support. Thus, the circumferential groove is made accessible to allow mounting by longitudinal translation of each sealing gasket in the lateral opening and then by rotation.

The annular seal could be of any type. For example, it could be of the type described with reference to the and comprise two radially internal annular wall sectors 510a, 510b each formed monolithically with a radial tab 515. Each radial tab 515 is connected to the same tab 514 arranged circumferentially between the two tabs 515. Details of the production of the joint can be read with reference to the . The coupling of seal support 505 and seal 401 can be made with other seals of the present document such as the seal described with reference to figures 10 to 15.

After mounting all the seal sectors, an annular flange 519 is mounted on the downstream face of the seal in order to block the lateral opening. The flange thus comprises protrusions 517 bolted to the seal support 505.

There illustrates a particular embodiment of a hydrostatic sealing annular seal 600.

As previously described, a hydrostatic annular seal 600 comprises a radially inner annular wall and a radially outer annular wall between which elastically deformable members are formed. The present description in relation to the is applicable to any of the annular seals described with reference to the figures. The elastically deformable seal could be of the type described with reference to the , or one of figures 10 to 15. On the , we can see a radial leg 618 and a blade 620 or elastically deformable lamella.

The radially inner annular wall is sectorized and comprises a plurality of sectors 610 arranged circumferentially end-to-end. Each sector 610 comprises a first circumferential edge 612 and a second circumferential edge (not shown) circumferentially opposite the first edge 612. The first circumferential edge 612 of a sector 610 is placed circumferentially end-to-end with a second circumferential edge of a circumferentially adjacent sector 610.

As illustrated in the in relation to a first circumferential edge 612 of a sector 610, a slot 614 is formed in the thickness of the sector 610 and in the first circumferential edge 612 thereof. This slot 614 opens out circumferentially and may have a substantially rectangular shape in section. The same slot 614 is formed in the second circumferential edge of each sector pad.

According to the present document, a tab 616 is mounted partly in a slot 614 of a first circumferential edge 612 and in a circumferentially facing slot 614 of a second circumferential edge of a circumferentially adjacent pad 610.

As described with reference to the , each internal sector 610 may comprise a radially internal surface comprising a first portion 610a of substantially cylindrical surface, a second portion 610b of surface formed by a recess, a third portion 610c of substantially cylindrical surface and preferably a fourth portion 610d of truncated surface with a section increasing downstream. The recess extends from one circumferential end to the other of the sector 610 and has a concave curved shape which may be formed of a longitudinal succession of flat surfaces. A housing as mentioned in could also be formed in the recess.

It is observed that the slot 614 is formed substantially radially outside the recess such that a plane perpendicular to the longitudinal axis intercepts both the slot 614 and the recess.

In a particular embodiment, the slot extends to the third part 610c. The slot is open circumferentially and axially upstream. The upstream opening is closed by a sealing part (not shown) which prevents air circulation at the upstream outlet. Sealing such as that described with reference to FIGS. 5 to 7 can be used.

We now refer to the representing a hydrostatic annular seal 700 comprising a radially outer annular wall 710 and a radially inner annular wall 712 which is sectorized and formed of a plurality of sectors 714 arranged circumferentially end to end. Elastically deformable members 716 are arranged radially between the inner 712 and outer 710 walls. This seal 700 can be mounted at the radially inner end of an annular row of stator blades of a turbomachine. It could be mounted at any other location where it could perform the same function, for example at a radially outer end of an annular row of stator blades or at the interface between any rotating and fixed part in a turbomachine.

As we can see, the sector of the has the same shape as the sector of the . However, what is described below with reference to the is also applicable to the other joints of this document, in particular to the joint as shown in at 12.

Each elastically deformable member 716 may comprise two substantially radial legs 718, 720, a first 720 of which is connected to the sector 714 and a second 718 of which is connected to the external annular wall 710. The two legs 718, 720 are connected to each other by elastic blades 722.

It is proposed here to form a housing 724 on the radially internal face of each sector 714, this housing 724 opening radially inwards, this housing 724 having upstream and downstream faces 724a, circumferential faces 724b formed in the thickness of the sector 714. The housing also comprises a bottom wall 724c connecting the radially external ends of the circumferential walls 724b, upstream and downstream 724a. Parts A, B, C and D of the represent different joint orientations and cross-sections for Part B, Part C and Part D.

It is observed that the housing 724 may have a substantially parallelepiped shape, that is to say, the side or circumferential walls 724b, upstream and downstream 714a and bottom 724c are substantially flat, if we disregard the connecting radii of said walls between them. The housing 724 may be substantially centered circumferentially on the circumferential extent of the sector 714.

The housing 724 thus produced does not open circumferentially or longitudinally since the circumferential faces 724b facing each other and the upstream and downstream faces 724a facing each other are formed in the thickness of the sector 714.

The housing 724 may extend circumferentially for a distance less than 80% of the circumferential extent of the sector. Also, the housing 724 may extend longitudinally for a distance less than 50% of the longitudinal extent of the sector 714.

In a particular embodiment of the seal 700, each housing 724 has a depth of at least 50% of the maximum radial dimension of the sector 714.

In Figure 37D, it is observed that the radially internal surface of the sector 714 comprises a first substantially cylindrical surface portion 726a, a second surface portion 716b forming a recess, a third substantially cylindrical surface portion 726c and a fourth frustoconical surface portion 726d with a section increasing downstream.

According to the present document, the housing 724 is formed in the annular recess 726b. The recess 726 may have a concave curved shape. It is here composed of a succession of conical surfaces.

The elastic members 716 could have the shape of those described with reference to the to 12. In this case, the primary and secondary sectors are each provided with a housing 724 formed in the thickness thereof. For the rest of the characteristics relating to the elastic member, reference will be made to the description made with reference to at 12.

The integration of a 724 housing as described with reference to the could be made on any of the ring seals and assemblies described herein.

The annular seal 700 could further comprise slots formed in the circumferential edges of each sector for receiving a sealing tab as described with reference to the .

Reference is now made to the schematically representing a partial view of an assembly 800 for a longitudinal axis turbomachine according to the present document. Preferably, such an assembly is implemented in a turbine, in particular a low pressure turbine, of a turbomachine such as previously described with reference to the . This document also concerns any type of turbomachine comprising such a turbine, for example a turboprop or a turbojet for an aircraft.

The assembly 800 comprises a cylindrical shell 811 intended to be driven in rotation about the longitudinal axis and an annular row of stator blades 820. The assembly 800 may also comprise two annular rows of moving blades 810 arranged longitudinally on either side of the annular row of stator blades 820 and connected to each other by the cylindrical shell 811. The annular row of stator blades 820 carries an annular hydrostatic seal 822 arranged radially inside the annular row of stator blades 820 and radially outside the cylindrical shell 811, the annular hydrostatic seal 822 cooperating in a contactless seal with the cylindrical shell 811.

In addition, the cylindrical ferrule 811 comprises an annular layer 812 facing the hydrostatic annular seal 822 which is made of a first material having a hardness greater than a hardness of a material of a radially internal end 823 of the hydrostatic annular seal 822 facing the annular layer 812.

The use of a harder material for the annular layer improves the mechanical strength of the cylindrical shell compared to the hydrostatic annular seal. Thus, in the event of rotor eccentricity following a sudden operation or a breakdown, such an assembly mechanically protects the cylindrical shell in the event of prolonged contact between the hydrostatic annular seal and the cylindrical shell. The mechanical integrity of the cylindrical shell can thus be preserved.

The cylindrical ferrule 811 has in particular a circular section of constant radius along the longitudinal axis on at least one longitudinal portion of the cylindrical ferrule. This shape allows for better control of the clearance between the hydrostatic annular seal and the cylindrical ferrule. In particular, the cylindrical ferrule 811 is devoid of lip seals.

The hydrostatic annular seal preferably comprises a radially outer annular wall, a radially inner annular wall and a plurality of elastically deformable members, in particular distributed circumferentially around the longitudinal axis. Each of the plurality of elastically deformable members comprises a first substantially radial tab connected to the radially outer annular wall, a second substantially radial tab connected to the radially inner annular wall and at least one elastically deformable blade extending circumferentially. Said at least one blade is connected to the first tab at a circumferential end and to the second tab at an opposite circumferential end. In other words, the first tab provides the connection between one of the circumferential ends of said at least one blade and the radially outer annular wall, and the second tab provides the connection between the other of the circumferential ends of said at least one blade and the radially inner annular wall. The hydrostatic annular seal can thus deform radially thanks to the flexibility offered by said at least one blade connecting together the radially internal annular wall and the radially external annular wall. The radially internal and external annular walls, the tabs and the blades are in particular dimensioned to allow the radial deformation of the hydrostatic annular seal to be controlled, and therefore to control a clearance between the hydrostatic annular seal and the cylindrical shell. Such a deformable member is illustrated in .

The elastically deformable member could also be of the type described with reference to Figures 9 to 12.

The first material must then have a harderness greater than that of the skate material.

The pad, made of a material with greater abradability than the ferrule coating, ensures that wear during contact between the ferrule and the pad of the hydrostatic seal occurs only on the pad and not on the ferrule.

The shoe may in particular have an aeraulic shape. This allows, by phenomena of depression and overpressure on either side of the shoe, the increase of a clearance between the cylindrical shell and the hydrostatic annular seal when they approach each other, and conversely, the reduction of the clearance between the cylindrical shell and the hydrostatic annular seal when they move away from each other.

The hydrostatic annular seal is preferably made of a metallic material.

The first material may also have an abrasion resistance greater than the abrasion resistance of the material of the radially inner end 823 of the hydrostatic annular seal 822 opposite the annular layer 812.

A portion 814 of the cylindrical ferrule 811 extending longitudinally from one to the other of the two annular rows of moving blades 810 is in particular made of a first material having a hardness greater than the hardness of the second material. In other words, the portion 814 of the cylindrical ferrule 811 made of the second material connects the two annular rows of moving blades. The second material may in particular be adapted to ensure the mechanical transmission of a torque between the two annular rows of moving blades 810.

The second material may have an abrasion resistance lower than the abrasion resistance of the first material.

The second material can be steel, a nickel-based alloy or a cobalt-based alloy.

The first material and the second material have in particular mechanical resistance and temperature resistance characteristics consistent with the thermomechanical operating conditions of the turbomachine.

The annular layer 812 may have a longitudinal dimension L1 greater than a longitudinal dimension L2 of the hydrostatic annular seal 822 along the longitudinal axis X. Such a characteristic makes it possible to ensure that the hydrostatic annular seal 822 can be radially opposite the annular layer 812 even in the event of relative longitudinal movement between the cylindrical shell 811 and the annular row of stator blades 820. This relative longitudinal movement is commonly referred to as slewing. Slewing may occur in different operating phases of the turbomachine.

In reference to the , the cylindrical ferrule 811 may have an annular recess 813 intended to receive the annular layer 812. In particular, the annular recess 813 and the annular layer 812 may be of the same thickness. In other words, the annular layer 812 may not add any excess thickness to the cylindrical ferrule 811.

In reference to the , the annular layer 812 may form a projection relative to a first radially external surface 815 of the cylindrical shell 811. The first radially external surface 815 of the cylindrical shell 811 may in particular correspond to a surface that is the most radially inside a radially external periphery of the cylindrical shell 811. For example, the annular layer 812 may form a ring, i.e. extend over 360°. The layer could be partially housed in the shell and partially formed as a projection relative to the external surface of the shell.

The annular layer 812 may have a radial thickness h so as to provide sufficient mechanical resistance to the annular layer in the event of contact between the cylindrical shell and the hydrostatic annular seal.

According to another aspect, there is described a method of manufacturing the assembly 100 as previously described. The method comprising the following steps:
- the installation of the annular layer 812 on the cylindrical shell 811,
- machining a radially external face 816 of the annular layer 812.

The method then makes it possible to ensure that the annular layer 812 complies with the dimensional constraints, geometric tolerances, and surface condition of the cylindrical shell 811.

Reference is now made to the schematically representing a partial section of an assembly 900 for a longitudinal axis turbomachine according to the present document, and two enlarged views of the assembly. Preferably, such an assembly is implemented in a turbine, in particular a low pressure turbine, of a turbomachine such as previously described with reference to the . This document also concerns any type of turbomachine comprising such a turbine, for example a turboprop or a turbojet for an aircraft.

The assembly 900 comprises a shroud 931 intended to be driven in rotation about the longitudinal axis X and a stator stage 920 extending around the longitudinal axis X and radially outside the shroud 931. The shroud 931 may in particular have a cylindrical shape, at least over a longitudinal portion of the shroud. The shroud 931 is in particular devoid of lip portions. The assembly 900 may also comprise two annular rows of moving blades 930 intended to be driven in rotation about the longitudinal axis X, the two annular rows of moving blades 930 being arranged longitudinally on either side of the annular row of stator blades 920 and connected to each other by the shroud 931.

The stator stage 920 comprises an annular row of stator blades 921. More specifically, the annular row of stator blades 921 comprises a radially outer annular platform and a radially inner annular platform 922 between which a plurality of blades extend. The annular row of stator blades 921 comprises a radial partition 923 which extends radially inward from the radially inner annular platform 922.

The stator assembly 920 also comprises a hydrostatic annular seal 950 carried by the annular row of stator blades 921 and radially opposite the shroud 931, the hydrostatic annular seal 950 being configured to cooperate in a contactless seal with the shroud 931.

In addition, the stator stage 920 and more particularly the annular seal comprises a stop system capable of coming into direct or indirect contact with the ferrule 931 and making it possible to limit the radial displacement of the seal.

In the context of an overspeed start of a turbine rotor comprising the shroud, the hydrostatic annular seal may come into contact with the shroud, under the effect of a radial expansion of the latter at overspeed. The stop system advantageously makes it possible to reinforce the contact between the stator stage 920 and the shroud 931 to contribute to braking the rotor in the event of overspeed. Such an assembly 910 thus makes it possible to passively brake the rotor. The assembly thus makes it possible to protect the mechanical integrity of the rotor in the event of overspeed.

More specifically, with reference to the , the hydrostatic annular seal 950 comprises a radially external annular wall 951, a radially internal annular wall 952 and a plurality of elastically deformable members, in particular distributed circumferentially around the longitudinal axis. The hydrostatic annular seal 950 preferably comprises a ring 959 extending radially outwards from the radially external annular wall 951. For example, the ring may have a U-shaped section, the two branches of the U being arranged on either side of the radial partition. The two branches of the U and the radial partition can be put into position via centering pins.

The radially inner annular wall 952 and the radially outer annular wall 951 may in particular be formed respectively of a plurality of inner wall sectors arranged circumferentially end to end and of a plurality of outer wall sectors arranged circumferentially end to end. Each of the inner wall and outer wall sectors are in particular connected to an elastically deformable member of the plurality of elastically deformable members.

Referring to Figures 43, 44 and 45, each of the plurality of elastically deformable members 953 comprises a first substantially radial leg 955 connected to the radially outer annular wall 951, a second substantially radial leg 956 connected to the radially inner annular wall 952 and at least one elastically deformable blade 954 extending circumferentially. As such, only the blades 954 are capable of deforming, the legs 955, 956 are non-deformable.

Said at least one blade 954 is connected to the first leg 955 at a circumferential end and to the second leg 956 at an opposite circumferential end. In other words, the first leg 955 provides the connection between one of the circumferential ends of said at least one blade 954 and the radially external annular wall 951, and the second leg 956 provides the connection between the other of the circumferential ends of said at least one blade 954 and the radially internal annular wall 952. The hydrostatic annular seal can thus deform radially thanks to the flexibility offered by said at least one blade connecting together the radially internal annular wall and the radially external annular wall.

The radially internal and external annular walls, the legs and the blades are in particular dimensioned to allow the radial deformation of the hydrostatic annular seal to be controlled, and therefore to control a clearance between the hydrostatic annular seal and the ferrule. A first clearance J1 is defined (shown in the ) between the hydrostatic annular seal 950 and the ferrule 931, corresponding to a nominal clearance in operation between the hydrostatic annular seal and the ferrule. Alternatively, the first clearance can be defined as a cold clearance of the turbine.

More specifically, the first leg 955 includes a radially outer end directly connected to a radially inner face of the radially outer annular wall and a radially inner end that is devoid of direct connection to the radially inner annular wall. Similarly, the second leg 956 includes a radially inner end directly connected to a radially outer face of the radially inner annular wall and a radially outer end that is devoid of direct connection to the radially outer annular wall.

In addition, the first leg 955 and the second leg 956 are particularly adapted to not deform radially. Only the leg 956 is able to move radially with the radially internal annular wall and to approach (or move away from) the radially external annular wall.

Each of the plurality of elastically deformable members 953 may in particular comprise a plurality of radially spaced blades 954, for example two blades. The blades are in particular substantially parallel to each other.

The radially internal annular wall can carry an abradable pad 958 arranged radially opposite the ferrule 931 and capable of wearing in the event of contact with the ferrule 931.

The abradable pad 958 may in particular have an aeraulic shape. This allows, by phenomena of depression and overpressure on either side of the pad, the increase of a clearance between the ferrule and the hydrostatic annular seal when they approach each other, and conversely, the reduction of the clearance between the ferrule and the hydrostatic annular seal when they move away from each other.

In reference to the schematically representing an exemplary embodiment of the assembly according to the present document, the stop system 940 comprises at least a first radial stop element 941 carried by the radially external annular wall 951 facing radially the second leg 956 of one of the plurality of elastically deformable members 953. Thus, the first radial stop element can come into abutment against the second leg. The stop elements are here radial protrusions.

Said at least first radial stop element 941 can also be carried by the radially internal annular wall 952 radially opposite the first leg 955 of one of the plurality of elastically deformable members 953. Thus, the first radial stop element can come into abutment against the first leg.

Said at least first radial stop element 941 can also be carried by the second leg 956 of one of the plurality of elastically deformable members 953 radially facing the radially external annular wall 951, or carried by the first leg 955 of one of the plurality of elastically deformable members 953 radially facing the radially internal annular wall 952. Thus, the first radial stop element 941 can come into abutment against the radially internal annular wall when it is carried by the first leg, or against the radially external annular wall when it is carried by the second leg.

The stop system 940 may also comprise at least two first radial stop elements 941, one being carried by the second tab 956 radially opposite the radially external annular wall 951 or vice versa, and the other being carried by the first tab 955 radially opposite the radially internal annular wall 952 or vice versa.

Said at least one first radial stop element 941 makes it possible to reinforce the radial contact between the hydrostatic annular seal and the ferrule, and thus to improve the braking of the ferrule in the event of overspeed. In addition, the first radial stop element is then advantageously directly integrated into the hydrostatic annular seal, making it easier to implement from the point of view of manufacturing the assembly. In particular, the first radial stop element 941 can be formed in the mass of the hydrostatic annular seal.

The first radial stop element 941 may form a radial protrusion.

The first radial stop element 941 may have a first stop surface 945 substantially parallel to a face against which the first stop surface is capable of coming into abutment.

As shown in the , a second clearance J2 between the first abutment surface 945 and the face against which the first abutment surface is capable of abutting, must be less than or equal to the first clearance J1. As shown in the a second clearance J2, between the first abutment surface 945 and the face against which the first abutment surface is capable of coming into abutment and may be 0.2 mm or more. Thus, when the ferrule deforms radially outwards under the effect of an overspeed, the radially outward movement of the radially internal annular wall of the seal is limited, which makes it possible to ensure contact between this wall and the ferrule 931.

The first radial stop element 941 may extend over part or all of the longitudinal dimension of the hydrostatic annular seal 950.

In particular, the stop system 940 preferably comprises a plurality of first radial stop elements 941. For example, each of the plurality of elastically deformable members may comprise one of the plurality of first radial stop elements 941.

Figures 44 and 45 show exemplary embodiments of the assembly according to the present document. The assembly may comprise at least one second radial stop element 942, 943 forming a finger extending radially inward from the annular row of stator blades. Said at least one second radial stop element 942, 943 is adapted to enter into radial abutment with the radially inner annular wall 952 (as shown in ) and/or with the second leg 956 of one of the plurality of elastically deformable members 953 (as shown in ).

The second radial stop element 942, 943 may be connected to the radial partition 923 at a first end. The second radial stop element 942, 943 may comprise a second end opposite the first end facing the radially external face of the radially internal annular wall 952 or the radially external end of the second leg 956 of one of the plurality of elastically deformable members.

The second radial stop element 942, 943 may in particular extend over part or all of the longitudinal dimension of the radial partition 923.

The second radial stop element can radially pass through at least one opening 957a, 957b, 957b’ provided in the hydrostatic annular seal.

In reference to the , the second radial stop element 942 is able to come into radial abutment with the second tab 956. A first opening 957a is notably provided in the radially external annular wall 951, the first opening 957a being opposite the radially external end of the second tab 56. Thus, the second radial stop element 942 passes through the first opening 957a.

In reference to the , the second radial stop element 943 is capable of coming into radial abutment with the radially internal annular wall 952, in particular with the radially external face of the radially internal annular wall 952. The second radial stop element 943 passes through a first opening 957a provided in the radially external annular wall 951, and a second opening 957b, 957b' provided in each blade of said at least one blade 954. The second radial stop element 943 may in particular be circumferentially positioned between the first tab 955 and the second tab 956, in particular substantially in the middle of the first tab 955 and the second tab 956.

The second radial stop element 942, 943 may have a second stop surface 946 substantially parallel to a face against which the second stop surface is capable of coming into abutment.

A third clearance between the second abutment surface and the face against which the second abutment surface is capable of coming into abutment may preferably be of the same order of magnitude as the first clearance. This technical characteristic makes it possible to ensure that, when the ferrule extends radially under the effect of an overspeed, then the hydrostatic annular seal and the ferrule come into contact, the hydrostatic annular seal cannot deform radially enough to allow a flow of gas to pass between the hydrostatic annular seal and the ferrule.

The assembly may include a plurality of second radial stop members 942, 943. For example, each of the plurality of elastically deformable members may include one of the plurality of second radial stop members.

In reference to the , at least one third longitudinal stop element 944 of the stop system 940 can advantageously extend longitudinally from the hydrostatic annular seal 950. Said at least third longitudinal stop element 944 is capable of coming into longitudinal abutment with a radial portion 932 of the annular ferrule 931 facing longitudinally. Such a feature makes it possible to ensure contact between the ferrule and the hydrostatic annular seal in the event of relative longitudinal movement between the ferrule and the stator stage, and in particular in the event of breakage of the rotor shaft. Thus, said at least one third longitudinal stop element can advantageously contribute to braking the rotor in the event of overspeed.

Said at least one third longitudinal stop element 944 may preferably have an annular shape.

The stop elements have been presented individually in a non-limiting manner in the preceding description, the assembly being able to comprise a combination of said at least one first radial stop element, said at least one second radial stop element and said at least one third longitudinal stop element.

Claims (10)

Seal (700) for an aircraft turbomachine comprising a plurality of seal sectors distributed circumferentially around a longitudinal axis (X), each seal sector comprising a radially external annular wall sector (710) and a radially internal annular wall sector (712) connected to each other by at least one elastically deformable member, characterized in that the radially external annular wall sectors form a monolithic external shell and the radially internal annular wall sectors are arranged circumferentially end-to-end and in that each radially internal annular wall sector (714) comprises a housing (724) formed in the thickness of the internal sector (714) and opening radially onto the radially internal surface of the radially internal annular wall sector, this housing (724) having upstream (724a) and downstream (724a) faces and circumferential faces (7244) dug into the thickness of the radially internal wall sector (714). An annular seal according to any preceding claim, wherein each housing (724) is substantially circumferentially centered on the circumferential extent of the radially inner annular wall sector (714). An annular seal according to any preceding claim, wherein the housing (724) comprises a bottom face (724c). Annular joint according to the preceding claim, in which the circumferential faces (724b) and/or the upstream and downstream faces (724a) and/or the bottom face of each radially internal wall sector are substantially flat, and preferably substantially parallel two by two so as to form a parallelepiped. An annular seal according to any preceding claim, wherein the housing (724) is formed in a recess (726b) in the radially inner surface of the radially inner annular wall sector (714), the recess (726b) extending from one circumferential end to the other of the radially inner annular wall sector (714) and longitudinally having a concave curved shape. An annular seal according to claim 5, wherein the radially inner surface of each radially inner annular wall sector comprises a first substantially cylindrical surface portion (726a), a second surface portion (726b) forming the recess, a third substantially cylindrical surface portion (726c) and preferably a fourth frustoconical surface portion (726d) with a section increasing downstream. An annular seal according to any preceding claim, wherein each radially inner annular wall sector (714) comprises a first circumferential edge and a second opposite circumferential edge each comprising a slot (614) and wherein a tab (616) is mounted partly in a slot of a first circumferential edge (612) of a radially inner annular wall sector (714) and in a slot (614) opposite circumferentially of a second circumferential edge of an adjacent radially inner annular wall sector (714). Assembly comprising a cylindrical rotor shell intended to be driven in rotation about the longitudinal axis and a distributor which has a crown of stator blades, the distributor comprising a foot (403) at the radially internal end of the distributor, a seal according to any one of the preceding claims being mounted on the foot (403) of the distributor, and the seal cooperating in a contactless seal with the cylindrical rotor shell of the turbomachine arranged radially under the distributor. Turbine for an aircraft turbomachine, the turbine comprising a casing, an assembly according to the preceding claim and a rotor which comprises a cylindrical shroud driven in rotation about the longitudinal axis (X) and, the distributor being mounted in the casing and the cylindrical shroud being arranged radially under the distributor. Turbomachine, such as an aircraft turbojet or turboprop, comprising an assembly according to claim 8 or a turbine according to claim 9.