FR3086701A1 - WATERPROOFING OF DAWN - Google Patents

Abstract

The invention relates to a rotary assembly for an aeronautical turbomachine, comprising: - a disc (112) extending circumferentially around an axis (X) and having cells and teeth (120), - blades arranged in the cells, by means of a blade root (116), - a movable ring (28) disposed upstream of the disc, - an annular sealing ring (30) disposed axially between a downstream face (34) of the movable ring (28) and an upstream face of the teeth (120) of the disc (112) and of the feet (116) of blades, characterized in that the teeth (120) and the feet (116) of blades each have a axial projection (48a, 48b) directed towards the movable ring (28), the axial projections jointly forming a continuous annular surface (49) which faces radially against the annular ring (30), so that the annular ring comes into annular contact with the annular surface (49) continuous according to at least one radial component.

Description

WATERPROOFING OF DAWN

FIELD [001] The present invention relates to a rotary assembly for a turbomachine, such as in particular an aircraft turbojet engine, as well as a turbomachine comprising such an assembly.

BACKGROUND It is known that, in an aeronautical turbomachine, as in particular in a turbine part thereof, there is at least one rotary assembly 10 which comprises, as illustrated in FIGS. 1 and 2 under the art anterior, and along an axis X of rotation of the discs 12; 12a, 12b stepped each carrying vanes 14 extending radially from the disk concerned. By their feet 16, the blades 14 are engaged axially and retained radially in cells 18 of the external periphery of each disk 12, formed alternately with teeth 20 of this disk 12. The blades 14 also include internal platforms arranged circumferentially end to end so as to define together the internal limit of a stream 22 through which hot gases flowing in the turbomachine flow.

It is specified that below:

- the axial direction extends along, or parallel to, the axis X of rotation of the rotary assembly,

the terms upstream AM and downstream AV are defined with respect to the axial direction of flow of the flow of hot gases in the stream 22, generally from upstream to downstream,

- the terms radially inwards and radially outwards are in relation to the axis X of rotation,

- the radially internal direction extends radially in the direction of the axis X of rotation,

- the radially external direction extends radially opposite the axis of rotation X, and

- the circumferential direction extends around the axis X of rotation.

Cooling air 24 is often taken, in a low-pressure or high-pressure compressor of the turbomachine for example, and routed to cavities 26 of bottom 27 of cell 18 in order to cool the disc 12 and protect the latter from heating caused by the hot gases from the flow of the vein 22 (see also FIG. 3).

We try to prevent the reintroduction of this cooling air 24 into the vein 22, especially as otherwise, it is necessary to take a larger amount of cooling air 24, which reduces the efficiency of the turbomachine.

In order to remedy this problem, it is known to interpose between two discs 12; 12a, 12b, axially successive, a movable ring 28 which maintains an annular sealing ring 30.

The movable ring 28 has a radial annular flange 33 for fixing arranged in abutment with a downstream radial annular flange 36 for fixing the upstream disc 12, 12a and an upstream radial annular flange 38 for fixing the downstream disc 12, 12b. The movable ring 28 has, from the radially outer end of its radial annular flange 33 for fixing, a substantially cylindrical wall 40 having an annular flange 42 downstream. The downstream annular flange 42 extends radially near the upstream face of the downstream disc 12,12b, and more particularly of the teeth 20 and the feet 16 of the blades. This downstream annular flange 42 has an annular groove 44 opening towards the downstream into which the annular rod 30 is inserted. The annular groove 44 has a radially external wall which comprises a downstream oblique face 34.

As illustrated in FIGS. 4 and 5, again under the prior art, the annular ring 30 is plated:

- axially against an upstream face 32a, 32b of the teeth 20 of the downstream disc 12, 12b concerned and of the feet 16 of corresponding blades, and

- axially and radially against the downstream oblique face 34 of the movable ring 28.

This annular ring 30 then allows insulation between an annular passage 33 of cooling air 24 and the stream 22 of hot gases located radially outside the annular ring 30.

However, it has been noted that, when the turbomachine is operating, each blade 14 typically has a degree of axial freedom in the cavity 18 which is allowed:

- on the one hand, by the differential expansions between the disc 12 and the blades 14, in particular when the latter are made of Ceramic Matrix Composite and the discs 12 are made of metal alloy,

- on the other hand, by an axial dimensioning of the feet 16 of blades nominally smaller than the axial dimensioning of the disc 12, in order to ensure that the ends of the feet 16 of blades do not protrude from the axial ends of the cells 18 , thus avoiding applying axial clamping stresses on the blade roots.

Such axial dimensioning induces interstices 46 (see FIG. 5) between the annular sealing ring 30 (applied axially against the upstream faces 32a of the teeth 20 of the disc), and the upstream faces 32b of the feet 16 of the blades. Part of the cooling air 24 supplied to the cavities 26 at the bottom of the cell circulates through these interstices 46 to the inter-blade cavities and no longer fulfills its primary function of cooling the cells 18. The amount of air cooling 24 leaking through the interstices 46 is not negligible and impacts the performance of the turbomachine.

Certainly the downstream annular flange 42 of the movable ring 28 is hooped against the upstream face of the disc 12. However, the annular flange has a clearance J with the blade roots 16 through which the air escapes. cooling having flowed through interstices 46 (see medallion in figure 5).

Furthermore, when the turbomachine is operating, the annular ring 30 is annularly highly stressed by the movement of the blades 14. The sealing therefore depends on the manner in which the annular ring 30 is deformed. Thus, fatigue of the annular ring 30 can make the sealing more random.

The present invention aims to avoid such a situation and to secure the seal, by providing a simple, effective and economical solution to at least some of these problems.

SUMMARY OF THE INVENTION [015] The present invention thus relates to a rotary assembly for an aeronautical turbomachine, the rotary assembly having an upstream side and a downstream side, and comprising:

at least one disc extending circumferentially around an axis (X) and having alveoli and teeth succeeding each other circumferentially around said axis (X), blades arranged in the alveoli, each by means of a foot d blade, a movable ring disposed upstream of the disc, an annular sealing ring disposed axially between a downstream face of the movable ring and an upstream face of the disc teeth and of the blade roots, the annular ring being held axially and radially by said movable ring, the assembly being characterized in that the teeth and the blade roots each have an axial projection directed towards the movable ring, the axial projections jointly forming a continuous surface which faces radially against the annular ring , so that the annular ring annularly comes into contact with the continuous annular surface according to at least one radial component.

The continuity of said continuous annular surface (formed by all of the circumferentially adjacent axial projections two by two) allows the annular ring to be applied against the latter so as to form a continuous and uniform annular contact over the whole. of the annular surface. This prevents the formation of axial gaps between the annular ring and the upstream faces of the blade roots, the axial dimension of which is smaller than that of the teeth. The absence of a gap implies an absence of cooling air leakage, in the outward radial direction, between the movable ring and the disc.

[017] In this way, the cooling air is entirely guided towards the cells receiving the blade roots and therefore entirely used for cooling the blade roots and the disc.

It is thus not necessary to extract from the turbomachine the aforementioned quantity of additional cooling air. In this way, the performance of the turbomachine is improved.

[019] The annular ring, such as a split ring, can be flexible.

Advantageously, the flexibility of the rod allows it to come to be pressed by centrifugal force against the annular surface of the movable ring, on the one hand, and the continuous annular surface formed by the axial projections of the teeth and feet. vanes, on the other hand. The annular ring is thus able to undergo a deformation which allows it to marry continuously the annular surfaces of the ring and the axial projections.

[021] The annular ring may have, in addition to the annular contact with said continuous annular surface, an axial annular contact with the upstream faces of the teeth and of the blade roots.

[022] The contact of the annular ring on separate annular surfaces makes it possible to increase the seal by having a double level of seal. In this way, only the cooling air escaping from the first sealing level, defined by the annular contact of the annular ring, is still to be blocked by the second sealing level, defined by the contact of the annular and radial ring. with the continuous annular surface formed by the axial projections.

[023] For contact with the annular ring, the axial projections may each comprise a continuous annular surface extending along an axial component, upstream, and a radial component towards the outside. [024] This makes it possible to limit the displacement radially outward of the annular ring and to offer a circumferential contact of the annular ring both radially and axially.

[025] The continuous annular surface formed by the axial projections can be defined by a chamfer.

[026] Such a profile, inclined axially and radially, of the radially internal face of the axial projections concerned will provide a continuous annular contact surface comprising an axial component and a radial component on which the annular ring can abut according to an axial component and a radial component.

[027] Alternatively, said continuous annular surface could have a curvilinear profile.

[028] We could thus take better account of a variation in the profile of the blades when my turbomachine is operating.

The curvilinear profile of the continuous annular surface can be convex. [030] When the turbomachine is in operation, the curvilinear profile allows the annular ring to remain in contact with the projections of the blade roots without deforming, although the blades are inclined downstream.

[031] The curvilinear profile may have a constant radius of curvature.

The constant radius of curvature makes it possible to maintain the annular contact of the annular ring with the axial projections of the blade roots at any time during the inclination of the blade when the turbomachine is operating, or when the blade extends. radially, when the turbomachine is stopped.

[033] In addition, the constancy of the radius of curvature makes the realization of the axial projections easier.

[034] The invention also relates to a turbine comprising a rotary assembly as described above. In addition, the invention relates to a turbomachine comprising a turbine comprising a rotary assembly, as described above.

The invention can be understood even better and other details, characteristics and advantages of the invention may appear on reading the following description given by way of nonlimiting example with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a sectional view of a turbine part according to the prior art;

Figure 2 is a perspective view of a disc and a blade mounted in a recess of the disc, according to the prior art;

Figure 3 is a side detail view, with local radial section (plane containing the axes X and Z), of Figure 1 illustrating only the downstream flange of the movable ring and a blade according to the prior art;

Figure 4 is a schematic sectional view along a plane passing through the axis X of the arrangement of the annular ring between the movable ring and the disc, according to the prior art;

Figure 5 is, with its medallion, a top view, in section of the disc, the blade roots, and the annular rod axially pressed against the latter, according to the prior art;

FIG. 6A is a partial schematic view of zone VI of FIG. 4, according to a first embodiment of the invention;

Figure 6B is a perspective view of the disc according to the first embodiment of the invention;

Figure 6C is a perspective view of the disc and the blades, according to the first embodiment of the invention and in the same view as Figure 2;

Figure 7A is a partial schematic view of said area VI of Figure 4, according to a second embodiment of the invention;

Figures 7B and 7C are two schematic views of the arrangement of the axial projections according to the second embodiment of the invention when the turbomachine is stopped and when the turbomachine is in operation, respectively.

DETAILED DESCRIPTION [036] The presentation of the prior art having been made in conjunction with FIGS. 1 to 5, FIGS. 6A to 7C illustrate that, according to the invention, and in the same structure as that of FIGS. 2 and 4 , the upstream annular radial faces 132a, 132b respectively (see FIGS. 6A and 7A in particular) of the teeth 120 and of the feet 116 of the blades 114 (shown in dotted lines) now each have an axial projection, respectively 48a, 48b (FIGS. 6A, 6B and 6C) or respectively 148a, 148b (Figures 7A, 7B and 7C).

[037] Each axial projection extends axially in the direction of the movable ring 28.

[038] These axial projections each comprise at least one oblique wall extending along an axial component (axis X), upstream and a radial component (axis Z), towards the outside. These oblique walls form circumferentially, end to end, an annular surface 49 (see FIG. 6A) continuous, annularly along the broken line 51 (FIG. 6C), against which the annular ring 30 annularly comes into contact, at a surface of contact 60, in order to avoid leakage of the cooling air 24 towards the vein 22.

[039] In a first embodiment, illustrated in FIGS. 6A to 6C, the axial projections 48a, 48b respectively have a radially internal annular face, respectively 50a, 50b, a radially external annular face, respectively 52a, 52b, and a face upstream, respectively 54a, 54b, connecting the radially inner and outer annular faces. The radially internal face, respectively 50a, 50b, is oblique (62a, 62b in FIG. 6B and 6C, and 154a, 154b in FIG. 7B) and extends along an axial component (X) downstream and a radial component ( Z) inwards, forming a chamfer 62a, 62b respectively. Each chamfer defines a contact surface 60 with the annular ring 30, comprising an axial component (X) and a radial component (Z).

[040] Against annular rod 30 thus comes axially and radially into abutment against the chamfers 62a and 62b, alternately on its circumference. [041] In a second embodiment, illustrated in FIGS. 7A to 7C, the axial projections and their walls are referenced added by a hundred with respect to the references of the first embodiment.

[042] The upstream face 154a, 154b of each of the axial projections 148a, 148b, now has a curvilinear profile. This curvilinear profile extends along an axial component (X) and a radial component (Z) and always forms a contact surface 60 against which the annular ring 30 comes axially and radially into abutment.

[043] Preferably, the axial projections 148a, 148b of the teeth 120 and of the feet 116 of the blades are identical, and even more preferably, the curvilinear profile of the upstream face 154a, 154b is convex. The curvilinear profile can have a constant radius of curvature.

[044] As mentioned in paragraph [008] of the application and illustrated in Figures 1 and 4 of the prior art, the annular ring 30 also has an annular contact according to an axial component (X) and a radial component (Z) on a contact surface 56 of the oblique face 34 of the downstream annular flange 42 of the movable ring 28.

[045] The annular ring 30 thus comes axially and radially into contact on a continuous annular surface of the movable ring and against the continuous annular surface 49 formed by the axial projections.

[046] As specified in paragraph [012] of the application, the downstream annular flange 42 of the movable ring 28 is hooped from a downstream radial surface 35 against the upstream face 132a of the teeth 120 of the ring 112.

[047] In addition to contact with the movable ring 28 and the axial projections, the annular ring 30 may also have another annular contact, according to a strictly axial component (X), with the teeth 120 and the blade roots 116 This contact is made on a radial annular contact surface 58.

[048] The rod can thus have first and second contact surfaces 58, 60 with each of the upstream faces 132a, 132b of the teeth 120 and the feet 116 of the blades.

[049] Stepped on the leakage path of the cooling air 24 in the vein 22, these two contact surfaces 58, 60 make it possible to significantly improve the sealing of the annular passage 33 of cooling air 24. Only l the air leaking through contact gaps 46 at the level of the first contact surface 58, reaches the contact zone of the annular ring 30 with the continuous annular surface 49 forming the second contact surface 60.

[050] Figures 7B and 7C illustrate the positioning of the axial projections 148a, 148b according to the second embodiment, depending on whether the turbine is stopped or in operation, respectively.

[051] Figure 7B illustrates the contacts of the annular ring 30 with the axial projections 148a, 148b of the teeth 120 and the feet 116 of the blades, when the turbine is stopped. The annular ring 30 comes into contact with substantially the same contact surfaces - 58; 60, 60a, 60c - either against the upstream face 154a with the annular profile of the teeth 120 or against the upstream face 154b of the feet 116 of blades.

[052] Figure 7C illustrates the contacts of the annular ring 30 with the axial projections 148a, 148b of the teeth 120 and the feet 116 of the blades when the turbine is in operation.

[053] When the turbomachine is operating, the blade 114 has a degree of axial freedom in the cavity 18 which is allowed:

on the one hand, by the fact that the axial dimensioning of the blade roots 116 must be nominally smaller than the axial dimensioning of the disc 112, and

- on the other hand, by the differential expansions between the disc 112 and the vanes 114, in particular when the latter are formed from Ceramic Matrix Composite and the discs are made of metal alloy. [054] The blade 114 can thus move and have an inclination towards the downstream induced by the force of the flow of hot gases from the vein in the direction of the blades 114.

[055] When the blades 114 are inclined, axially downstream (X) and radially outward (Z), at high speed, the annular ring 30 can no longer come to bear against the same contact surfaces 60, as this is the projections (148a, 148b respectively) of the teeth 120 or the feet 116 of the blades. The blades 114 being inclined, the axial projections 148b of the feet 116 of the blades are also inclined.

[056] When the turbine is stopped, the annular ring 30 comes into contact with a second contact surface 60; 60a and when the turbomachine is operating, the annular ring 30 comes into contact with another second contact surface 60; 60b, when the turbine is in operation. The second contact surfaces 60; 60a, 60b of the axial projections 148b of the feet 116 of the blades are at least partly distinct.

[057] When the turbomachine is operating and the blades are inclined, the second contact surface 60; 60b is located close to the radially internal end of the upstream face 154b of the axial projection 148b, while remaining in contact with the upstream face 154b with a curvilinear profile. While, when the turbomachine is stopped, the annular rod 30 comes into contact with the second contact surface 60; 60a which is located, at least in part, radially outside the second contact surface 60; 60b, when the turbomachine is operating.

[058] Regarding the teeth 120, the annular ring 30 comes into contact with the same second contact surface 60c of the axial projections 148a of the teeth 120, whether the turbomachine is in operation or stopped.

[059] Regardless of the change in the second contact surface

60a, 60b of the projections 148b of the feet 116 of the blades, depending on whether the turbomachine is in operation or not, the annular ring 30 annularly comes into continuous contact with the annular surface 49 formed by the projections 148a, 148b of the teeth 120 and feet 116 of blades.

[060] In this way, the annular ring 30 is no longer strongly stressed by 10 the displacement of the blades 114. As soon as the contact surface 60, 60a,

60b, 60c of the projections 148a, 148b pivots as a function of the inclination of the blades, the annular ring 30 is not deformed. This annular ring 30 is therefore subjected to lower fatigue than the annular ring 30 according to the prior art.

Claims (10)

1. Rotary assembly (10) for an aeronautical turbomachine, the rotary assembly (10) having an upstream side and a downstream side, and comprising: at least one disc (112) extending circumferentially around an axis (X) and having alveoli (18) and teeth (120) succeeding each other circumferentially around said axis (X), blades (114) arranged in the cells (18), each by means of a blade root (116), a movable ring (28) disposed upstream of the disc (112), an annular sealing ring (30) disposed axially between a face downstream (34) of the movable ring (28) and an upstream face (132a, 132b) of the teeth (120) of the disc (112) and of the feet (116) of blades, the annular ring (30) being held axially and radially by said movable ring (28), the assembly being characterized in that the teeth (120) and the feet (116) of blades each have an axial projection (48a, 48b, 148a, 148b) directed towards the movable ring (28), the axial projections (48a, 48b, 148a, 148b) jointly forming a continuous annular surface (49) which radially faces the annular ring (3 0), so that the annular ring (30) annularly comes into contact with the annular surface (49) continues according to at least one radial component. 2. The assembly of claim 1, wherein the annular ring (30) is flexible. 3. The assembly of claim 1 or 2, wherein the annular ring (30) has in addition to the annular contact with the annular surface (49) continues, an axial annular contact with the upstream faces (132a, 132b) of the teeth (120 ) and blade roots (116). 4. The assembly as claimed in one of claims 1 to 3, in which, for contact with the annular ring (30), the axial projections (48a, 48b, 148a, 148b) each have a said continuous annular surface (49) extending along an axial component, upstream, and a radial component towards the outside. 5. Assembly according to any one of the claims 5 above, wherein the continuous annular surface (49) is defined by a chamfer (62a, 62b). 6. Assembly according to any one of the preceding claims, in which the continuous annular surface (49) has a curvilinear profile. 10 7. The assembly of claim 6, wherein the curvilinear profile of the continuous annular surface (49) is convex. 8. The assembly of claim 6 or 7, wherein the curvilinear profile has a constant radius of curvature. 9. Turbine characterized in that it comprises a rotary assembly (10) for a turbomachine according to one of claims 1 to 8. 10. Turbomachine characterized in that it comprises a turbine according to claim 9 and a rotary assembly (10) for a turbomachine, according to one of claims 1 to 8.