FR3058758A1 - TURBOMACHINE, SUCH AS A TURBO AIRBORNE OR TURBOPROPULSER - Google Patents

Abstract

The invention relates to a turbomachine, such as an airplane turbojet or turboprop, comprising a centrifugal compressor comprising a wheel equipped with blades, and an annular cover (7) delimiting with the wheel an annular vein (8) for the circulation of an air flow, said cover comprising a downstream portion attached to a casing of the turbomachine and an upstream portion held in position relative to said casing, via an annular shell (17). The shell (17) and the cover (7) delimit between them an annular space (27) in which is formed a retaining member (28) integral with the ferrule (17), said retaining member (28) delimiting with said ferrule (17) a groove (31) in which is mounted an annular sealing member (34), the annular sealing member (34) being mounted around a portion (21) of the cover (7) and being maintained supported by the retaining member (28) on a portion (24) of the ferrule (17).

Description

Holder (s): SAFRAN AIRCRAFT ENGINES Simplified joint-stock company.

Extension request (s)

Agent (s): ERNEST GUTMANN - YVES PLASSERAUD SAS.

TURBOMACHINE, SUCH AS FOR example A TURBOJECTOR OR AN AIRPLANE TURBOPROPELLER.

FR 3 058 758 - A1 fUy / The invention relates to a turbomachine, such as an airplane turbojet or turboprop, comprising a centrifugal compressor comprising a impeller equipped with blades, and an annular cover (7) delimiting with the impeller annular vein (8) for circulation of an air flow, said cover comprising a downstream part fixed to a casing of the turbomachine and an upstream part maintained in position relative to said casing, by means of an annular ferrule ( 17). The ferrule (17) and the cover (7) delimit between them an annular space (27) in which is formed a retaining member (28) integral with the ferrule (17), said retaining member (28) delimiting with said ferrule (17) a groove (31) in which is mounted an annular sealing member (34), the annular sealing member (34) being mounted around a part (21) of the cover (7) and being held supported by the retaining member (28) on a part (24) of the ferrule (17).

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Turbomachine, such as for example a turbojet or an airplane turboprop

The present invention relates to a turbomachine, such as for example a turbojet or an airplane turboprop.

Patent application FR3008750, in the name of the Applicant, discloses a turbomachine, such as for example an airplane turbojet or turboprop, comprising a high pressure compressor downstream of which is mounted a centrifugal compressor comprising a impeller fitted with blades. The turbomachine further comprises an annular cover delimiting with the impeller an annular vein for circulation of an air flow. The cover comprises a downstream part fixed to a casing of the turbomachine and an upstream part maintained in position relative to said casing, by means of an annular ferrule. The air from the centrifugal compressor is intended to supply a combustion chamber of the turbomachine, as is known per se.

There is a need to ensure sealing between the shell and the cover, while making it possible to compensate for possible differential expansion phenomena between the shell and the cover. Indeed, the ferrule and the cover can be made of different materials and / or be subjected to different temperatures in operation via different temperature gradients, so that these two elements can expand differently from one another. and therefore move relatively to each other.

The object of the invention is in particular to provide a simple, effective and economical solution to this need.

To this end, it provides a turbomachine, such as for example a turbojet or an airplane turboprop, comprising a centrifugal compressor comprising a impeller equipped with blades, and an annular cover delimiting with the impeller an annular vein for circulation of a air flow, said cover comprising a downstream part fixed to a casing of the turbomachine and an upstream part maintained in position relative to said casing, by means of an annular shroud, characterized in that the shroud and the cover delimit between them an annular space in which is provided a retaining member integral with the ferrule, said retaining member delimiting with said ferrule a groove in which is mounted an annular sealing member, the annular sealing member being mounted around 'a part of the cover and being held in abutment by the retaining member on a part of the shell.

The terms upstream and downstream are defined with respect to the direction of gas flow within the turbomachine.

The retaining member serves to hold the sealing member in position. Furthermore, the annular sealing member closes, at least in part, the annular clearance between said annular space and the annular flow stream of air flow, so as to seal between the ferrule and the cover.

The annular sealing member is for example a split ring capable of being elastically deformed.

In this way, the sealing member is able to tolerate thermal expansion of the cover, around which it is mounted. Furthermore, such an elasticity makes it possible to maintain, with a slight prestress, the sealing member bearing on the cover.

The upstream part of the cover may comprise a first cylindrical surface facing radially outwards, a first shoulder extending radially from said first cylindrical surface, the ferrule comprising, on the one hand, a second cylindrical surface facing radially inward , and on the other hand, at its part on which the sealing member is held in abutment, a second shoulder opposite the first shoulder and offset axially upstream relative to the first shoulder, the annular space being delimited by the first and second cylindrical surfaces and by the first and second shoulders of the cover.

In this case, the sealing member can be mounted without play around the first cylindrical surface and can be kept in abutment on the second shoulder by the retaining member.

The retaining member may be annular and have a generally L-shaped section, comprising a first branch extending axially, integral with the second cylindrical surface, for example by shrinking, and a second branch extending radially and delimiting with the second shoulder the annular groove in which the sealing member is mounted.

In addition, the ferrule may have a third cylindrical surface located upstream and radially inside with respect to the second cylindrical surface, an annular clearance being defined between the first cylindrical surface of the cover and the third cylindrical surface of the ferrule.

In particular, said annular clearance is between 0.3 mm and 1 mm, for example between 0.45 mm and 0.85 mm. The play may in particular be a function of the surrounding temperature.

Such play is sufficient to compensate for the effects of differential expansion between the shell and the cover in operation.

The annular shell and the cover can be made of two different materials.

In particular, the annular shell can be made of stainless steel and the cover can be made of a nickel-based superalloy.

In particular, stainless steel can contain about 0.12% carbon, 11-12.5% chromium and 2.5% nickel. This steel can be martensitic. Furthermore, this chrome steel can meet at least one of the following references: X12CrNiMoV12-3, X11CrNiMoV12, Z12CNDV12, jethete M152. Concerning the nickel-based superalloy, it can be an alloy whose components are substantially in the following proportions: Nickel 35% to 40%, Cobalt 12% to 16%, Niobium 4.3% to 5.2 %, Titanium 1.3% to 1.8%.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of nonlimiting example with reference to the appended drawings in which:

FIG. 1 is a view in axial section of a part of a turbomachine according to an embodiment of the invention,

FIG. 2 is a detailed view of FIG. 1, showing the positioning of the sealing member and of the seal in the annular space formed between the ferrule and the cover,

- Figure 3 is a perspective view of a part of the retaining member and the sealing member.

In what follows, the terms “upstream” and “downstream” are defined with respect to the direction of flow of the gases in the turbomachine. Likewise, the terms "radial" and "axial" are defined with respect to the axis of the turbomachine.

Figures 1 to 3 show a turbomachine, in particular a turbojet engine according to an embodiment of the invention. The turbomachine conventionally comprises, from upstream to downstream in the direction of flow of the gases in the turbomachine, a blower housed in a nacelle, a low-pressure compressor, a high-pressure compressor 2, a centrifugal compressor 3, a diffuser 4 , a combustion chamber, a high-pressure turbine and a low-pressure turbine.

The centrifugal compressor 3 comprises an annular impeller 5 fitted with blades 6, forming the rotor, and an annular cover 7 belonging to the stator and delimiting with the impeller 5 an annular vein 8 for circulation of an air flow. When the impeller 5 rotates, air from the high-pressure compressor 2 is sucked upstream of the centrifugal compressor 3, then is expelled at high pressure and in a radial direction, into the diffuser 4 located downstream of the centrifugal compressor 3.

The shape of the annular cover 7 is such that it follows with minimal play the surface swept by the radial ends of the blades 6 of the impeller 5. The cover 7 is moreover arranged so that its upstream end 9 ensures continuity of surface with the radially outer wall 10 of the stream 11 of the high-pressure compressor 2 and that its downstream end 12 provides surface continuity with the upstream wall 13 of the diffuser 4.

The downstream part of the cover 7 comprises a flange 14 fixed by means of bolts 15 to a fixed external casing 16 of the turbomachine. Furthermore, the upstream part of the cover 7 is held radially in position by means of an annular ferrule 17. Said ferrule 17 in particular comprises a downstream end 18 which is fixed to the casing 16 by means of bolts 19 and a upstream part 20 which cooperates with the upstream part of the cover 7 so as to maintain it in position.

As can be seen more clearly in FIG. 2, the upstream part 9 of the cover 7 comprises a first cylindrical surface 21 facing radially outwards, a first shoulder 22 extending radially from said first cylindrical surface 21 and being offset towards the downstream relative to the upstream end of the cover 7.

Furthermore, the upstream part 20 of the ferrule 17 comprises a second cylindrical surface 23 facing radially inwards, a second shoulder 24 opposite the first shoulder 22 and offset axially upstream relative to the first shoulder 22, and a third cylindrical surface 25 situated upstream and radially inside with respect to the second cylindrical surface 23, an annular clearance JR being delimited radially between the first cylindrical surface 21 of the cover 7 and the third cylindrical surface 25 of the ferrule 17. Said clearance annular JR is between 0.3 mm and 1 mm, for example between 0.45 mm and 0.85 mm (at a temperature of about 20 ° C).

The upstream part 20 of the ferrule 17 further comprises a third shoulder 26 extending radially inwards from the third cylindrical surface 25 and offset axially downstream relative to the second shoulder 24. The shoulder 26 is located at look upstream end 9 of the cover 7 and is spaced from said end 9 of an axial clearance JA.

An annular space 27 is delimited between the cover 7 and the shell 17 by the first and second cylindrical surfaces 21, 23 and by the first and second shoulders 22, 24.

A retaining member 28 is mounted in said annular space 27. The retaining member 28 is annular and has a generally L-shaped section, comprising a first branch 29 extending axially, integral with the second cylindrical surface 23, by example by shrinking, and a second branch 30 extending radially and delimiting an annular groove 31 with the shoulder 24.

The distance D1 between the radially internal periphery of the second branch 30 and the first cylindrical surface 21 is between 0.65 and 1.15 mm.

The upstream end of the first branch 29 has a radially outer chamfer 32. Furthermore, the downstream end of the first branch 29 has an annular recess 33.

A sealing member 34 is mounted in the annular groove 31 delimited by the second branch 29 and the second shoulder 24. The sealing member 34 is a split ring capable of being elastically deformed, of square section. The radially internal periphery 35 of the sealing member 34 is held with a slight radial prestress bearing on the first cylindrical surface 21 of the cover 7. Furthermore, the dimensions of the sealing member 34 and of the member retaining 28 are such that the upstream radial face 36 of the sealing member 34 is held in abutment on the second shoulder 24 of the ferrule 17. The rear radial face 37 of the sealing member 34 is in abutment on the second branch 30. The radially outer periphery 38 of the sealing member 34 is spaced from the radially inner cylindrical surface of the first branch 29, by a distance D2 less D1 and between 1 and 1.3 mm, by example.

The upstream and downstream ends of the cylindrical surfaces formed by the radially inner and outer peripheries 35, 38 of the sealing member 34 may include fillets 39 or chamfers.

In operation, the sealing member 34 is capable of deforming simultaneously and in the same proportions as the upstream part of the cover 7. The use of a split ring 34 also makes it possible to reduce the constraints relating to the dimensional tolerances of the different rooms.

The slot 40 of the sealing member 34 may have a width, that is to say a circumferential distance, of between 0.1 and 1 mm, preferably of the order of 0.4 mm. The slot 40 may have a baffle shape, as can be seen in FIG. 3. The baffle shape makes it possible to significantly limit the leakage section on cutting and to improve the seal, while avoiding the arc - end of the two parts.

The annular shell 17 is made for example of stainless steel, the cover 7 being made for example of a nickel-based superalloy. Furthermore, the retaining member 28 can be made of a nickel-based superalloy and the sealing member 34 can be made of a nickel-based superalloy.

The annular sealing member 34 closes the annular clearance JR between the annular space 27 and the annular vein 8 of the centrifugal compressor 3, so as to seal between the ferrule 17 and the cover 7.

The relative movement between the ferrule 17 and the cover 7 can also be limited by pressing the radially external periphery of the sealing member 34 on the first branch 29, by pressing the upstream end 9 of the cover 7 on the shoulder 26 of the ferrule 17, and / or by pressing the second branch 30 on the shoulder 22 of the cover 7.

In order to mount the sealing member 34 in the annular space 27, said member 34 can be glued to the shoulder 24 by means of glue points, the retaining member 28 being able to be mounted around of the sealing member 34 and hooped on the ferrule 17. The cover 7 can then be engaged so that the first cylindrical surface 21 is engaged inside the internal periphery 35 of the sealing member 34 thus pasted. During assembly, a shim can be introduced into the slot 40 of the sealing member 34 so as to facilitate the insertion of the upstream end 9 of the cover 7 into the sealing member 34, the shim can then be removed after assembly. It is possible to mount the sealing member 34 on the ferrule 17, then hoop the retaining member 28 and apply a point of adhesive at the level of the slot 40 while keeping the sealing member 34 open, positioning a wedge while the glue dries, for example about 20 seconds. This is enough to keep the sealing member 34 open while docking the cover 7. In use, the glue dots are destroyed due to the increase in temperature, the internal periphery 35 of the sealing 34 then being pressed elastically against the first cylindrical surface 21 of the cover 7.

Claims (9)

1. Turbomachine, such as for example an airplane turbojet or turboprop, comprising a centrifugal compressor (3) comprising a impeller (5) equipped with blades (6), and an annular cover (7) delimiting with the impeller ( 5) an annular stream (8) for circulation of an air flow, said cover (7) comprising a downstream part fixed to a casing (16) of the turbomachine and an upstream part maintained in position relative to said casing (16 ), via an annular ferrule (17), characterized in that the ferrule (17) and the cover (7) define between them an annular space (27) in which a retaining member (28) is formed integral with the ferrule (17), said retaining member (28) delimiting with said ferrule (17) a groove (31) in which is mounted an annular sealing member (34), the annular sealing member (34 ) being mounted around a part (21) of the cover (7) and being held in abutment by the retainer (28) on a part (24) of the ferrule (17). 2. Turbomachine according to claim 1, characterized in that the annular sealing member (34) is a split ring capable of being elastically deformed. 3. Turbomachine according to claim 1 or 2, characterized in that the upstream part of the cover (7) comprises a first cylindrical surface (21) turned radially outwards, a first shoulder (22) extending radially from said first cylindrical surface (21), the ferrule (17) comprising on the one hand a second cylindrical surface (23) turned radially inwards, and on the other hand, at its part on which the sealing member (34) is held in abutment, a second shoulder (24) opposite the first shoulder (22) and offset axially upstream relative to the first shoulder (22), the annular space (27) being delimited by the first and second cylindrical surfaces (21,23) and by the first and second shoulders (22, 24). ίο 4. Turbomachine according to claim 3, characterized in that the sealing member (34) is mounted without play around the first cylindrical surface (21) and is held in abutment on the second shoulder (24) by the member retainer (28). 5 5. A turbomachine according to claim 3 or 4, characterized in that the retaining member (28) is annular and has a generally L-shaped section, comprising a first branch (29) extending axially, integral with the second cylindrical surface (23), for example by shrinking, and a second branch (30) extending radially and 10 delimiting with the second shoulder (24) the annular groove (31) in which the sealing member (34) is mounted. 6. Turbomachine according to one of claims 3 to 5, characterized in that the shell (17) has a third cylindrical surface (25) located upstream and radially inside with respect to the 15 second cylindrical surface (23), an annular clearance (JR) being delimited between the first cylindrical surface (21) of the cover (7) and the third cylindrical surface (25) of the ferrule (17). 7. A turbomachine according to claim 6, characterized in that said annular clearance (JR) is between 0.3 and 1 mm. 20 8. Turbomachine according to one of claims 1 to 7, characterized in that the annular shell (17) and the cover (7) are made of two different materials. 9. Turbomachine according to claim 8, characterized in that the annular shell (17) is made of stainless steel, the cover (7) 25 being made of a nickel-based superalloy. 1/2 21 '35