TURBOMACHINE FOR AN AIRCRAFT

Abstract

Turbomachine (10) for an aircraft, comprising: - a centrifugal compressor (12), - a stator-diffuser assembly (28), - an annular combustion chamber (14), - an annular turbine distributor (36), - a turbine wheel (22), and - an annular sealing system (48) connected by a first annular flange (50) to the distributor (36) and, on the other hand, by a second annular flange (52) to the stator-diffuser assembly (48), characterized in that the second flange (52) comprises an annular wall (76) extending perpendicularly to the axis (A) and giving this flange a certain degree of flexibility. Figure for the abbreviation: Figure 3

Description

Title of the invention: TURBOMACHINE FOR AN AIRCRAFT Technical field of the invention

[0001] The present invention relates to a turbomachine for an aircraft. Technical background

[0002] An aircraft turbomachine comprises a gas generator having, from upstream to downstream in the direction of gas flow, at least one compressor, an annular combustion chamber, and at least one turbine. The compressor is supplied with air and compresses it. The compressed air is mixed with fuel and burned in the combustion chamber, which supplies combustion gases to the turbine. These combustion gases expand in the turbine and rotate its rotor, which in turn drives, via a common shaft, the compressor rotor.

[0003] A turbomachine can be equipped with one or more bodies, each comprising a compressor rotor connected by a shaft to a turbine rotor.

[0004] There are also turbomachines where a free turbine is mounted downstream of the turbomachine body(ies). A turbine is free insofar as its rotor is not connected by a shaft to a compressor rotor.

[0005] It is thus understood that a turbomachine can comprise several successive compressors (for example a low pressure compressor followed by a high pressure compressor), as well as several successive turbines (for example a high pressure turbine followed by a free turbine or a low pressure turbine).

[0006] Fig. 1 represents a very schematic aircraft turbomachine 10.

[0007] The turbomachine 10 comprises, from upstream to downstream, at least one compressor 12, here two in number, an annular combustion chamber 14, and at least one turbine 16.

[0008] The compressors 12 are of the centrifugal type whose rotors are formed by impellers 18. The rotors or impellers 18 of the compressors 12 are connected together by a portion of shaft 20.

[0009] The turbine rotor 16 is formed by a wheel 22 which is connected to the impellers 18 of the compressors 12 by another portion of shaft 24. The wheel 22, the impellers 18 and the portions of shaft 20, 24 form a rotating body of the turbomachine.

[0010] A first annular rectifier-diffuser system 26 is mounted at the outlet of the first centrifugal compressor 12 and a second annular rectifier-diffuser system 28 is mounted at the outlet of the second centrifugal compressor 12.

[0011] The combustion chamber 14 is here of the inverted type and includes an inlet 14a or upstream end which is located here at the rear of the chamber 14, and an outlet 14b or downstream end which is located at the front of the chamber 14.

[0012] The chamber 14 comprises two annular walls, respectively internal 30 and external 32, which define between them an annular combustion zone 34. At least part of the compressed air which exits the rectifier-diffuser system 28 enters the combustion chamber 14.

[0013] The outlet 14b of the chamber 14 is oriented axially downstream. For this, a front part of the chamber 14 is bent so that its external wall 32, which is located radially outside the chamber 14 on the rear part of the chamber 14, passes radially inside the chamber on its front part, and also that the internal wall 30 of the chamber, which is located radially inside the chamber 14 on its rear part, passes radially outside the chamber on its front part.

[0014] The turbine 16 is at least partially located radially inside the chamber 14 and comprises an annular distributor 36 and the aforementioned wheel 22. The distributor 36 is axially interposed between the outlet 14b of the chamber and the wheel 22 and comprises two annular walls, respectively internal 38 and external 40, connected respectively to the annular walls 30, 32 of the chamber 14. As can be seen in the drawing, due to the particular shape of the chamber 14, the internal wall 38 of the distributor 36 is connected to the external wall 32 of the chamber, and the external wall 40 of the distributor 36 is connected to the internal wall 30 of the chamber 14.

[0015] The distributor 36 is bladed and includes blades 41 extending between its internal wall 38 and external wall 40.

[0016] As can be more clearly seen in [Fig. 2], the downstream end of the outer wall 40 of the distributor 36 bears axially against an upstream end of a sealing ring 42 that surrounds the impeller 22. Furthermore, the impeller includes an annular platform 44 that extends axially along the inner wall 38 of the distributor 36. The impeller 22 also includes vanes 46 that extend radially outwards from the platform 44 to the sealing ring 42 and are separated from this ring by small radial clearances. The impeller 22 may be of the monobloc type, or its vanes 46 may be attached and mounted on a disc of the impeller 22.

[0017] Between the second centrifugal compressor 12 and the wheel 22 is mounted an annular sealing system 48 which aims to limit gas leakage axially along and outside the portion of shaft 24. This sealing system 48 therefore surrounds with a small radial clearance the portion of shaft 24 which connects the wheel 22 to the impeller of the centrifugal compressor 12.

[0018] The sealing system 48 is part of a stator of the turbomachine, and is connected to the rectifier-diffuser system 28 on the one hand, and to the distributor 36 on the other hand.

[0019] In the current technique illustrated in figures 1 and 2, the sealing system 48 is connected by a first annular flange 50 to the internal wall 38 of the distributor 36 and on the other hand by a second annular flange 52 to the rectifier-diffuser system 28.

[0020] The second flange 52 includes an internal annular flange 54 for fixing to an internal annular flange 56 of the first flange 50, and this first flange 50 includes an external annular flange 58 for fixing to an annular flange 60 of the internal wall 38 of the distributor 36. The flanges 54, 56 are fixed by screws or bolts 62 and the flanges 58, 60 are fixed by other screws or bolts 64.

[0021] The axial support of the distributor 36 on the sealing ring 42 ensures precise axial positioning of this distributor and improves the performance of the turbine 16 in this area. However, this configuration generates a statically indeterminate loop (represented by dashed lines in [Fig. 1]) which results in stresses in the parts. Indeed, in order to ensure axial support between the distributor 36 and the sealing ring 42, a pre-clamping is applied within the statically indeterminate loop. This pre-clamping generates a level of stress in the loop which induces mechanical stresses in the components.

[0022] One solution to this problem could be to incorporate some "flexibility" into the first connecting flange of the sealing system 48 to the distributor 36, for example by increasing the height or radial dimension of this flange and therefore the radial distance between the distributor 36 and the sealing system 48. However, this solution would result in a larger radial footprint for these parts. Therefore, this solution would not always be feasible, particularly in small turbomachinery.

[0023] The present invention proposes a solution to at least some of the problems mentioned above. Summary of the invention

[0024] The invention relates to an aircraft turbomachine, comprising:

[0025] - a centrifugal compressor extending around an axis,

[0026] - a rectifier-diffuser assembly extending around the axis and mounted at the output of the centrifugal compressor

[0027] - an annular combustion chamber extending around the axis, this chamber of combustion comprising two annular walls, respectively internal and external, which define between them an annular combustion chamber,

[0028] - an annular turbine distributor extending around the axis and mounted at the outlet of the combustion chamber, this distributor comprising two annular walls respectively internal and external connected respectively to the annular walls of the combustion chamber,

[0029] - a turbine wheel extending around the shaft and mounted at the outlet of the distributor turbine, the wheel being surrounded by a sealing ring which includes an upstream axial end against which the external wall of the distributor bears axially, the wheel comprising a disc which is connected to an impeller of the centrifugal compressor by a portion of tree extending around the axis, and

[0030] - an annular sealing system extending around the axis and around the portion of shaft, this sealing system being connected by a first annular flange to the internal wall of the distributor and on the other hand by a second annular flange to the rectifier-diffuser system, the second flange comprising a first internal annular flange fixed by screws or bolts to the sealing system,

[0031] characterized in that the second flange comprises an annular wall which is directly connected to the first flange and which extends perpendicularly to the axis, this wall having a height or radial dimension greater than or equal to a height or radial dimension of the first flange.

[0032] The invention thus proposes to impart flexibility to the second flange. This flexibility is achieved by the particular shape of the second flange, which includes a radial wall of relatively large radial dimensions. Unlike a frustoconical or curved wall, a radial wall in this environment allows for greater flexibility of the second flange and reduces the over-constraint of the aforementioned loop. The components traversed by the loop are thus subjected to less mechanical stress.

[0033] In the present application, "flexibility" means the fact that a part has an elastic deformation capacity, in particular in bending.

[0034] The turbomachine according to the invention may comprise one or more of the following stages or features, considered independently of each other or in combination with each other: - the first wall and the first flange of the second flange extend in the same plane perpendicular to the axis; - the first wall has a thickness or axial dimension less than that of the first flange of the second flange; - the first wall of the second flange is connected to the rectifier-diffuser system by a second annular wall of the second flange, this second annular wall having a truncated conical shape; - The turbomachine also includes a first annular plate which is supported by the second flange and which is axially interposed between the impeller of the centrifugal compressor and the second flange; - the first sheet metal has its outer periphery which is fixed to the flange, at the level of its junction with the rectifier-diffuser system, and its inner periphery which is fixed to the flange, at the level of the junction between its first flange and its first wall; - the outer periphery of the first sheet metal is engaged in an annular groove of the second flange, which opens radially inwards, and the periphery The internal part of the sheet metal is engaged in an annular groove of the second flange which opens radially outwards; - the first sheet metal extends at least partly along a downstream radial face of the centrifugal compressor impeller and defines an annular cavity with the flange;

[0035] — the second flange is formed in one piece with at least part of the system rectifier-diffuser; - the first flange includes on its inner periphery a second annular flange for fixing to the sealing system, and on its outer periphery a third annular flange for fixing to a fourth annular flange of the inner wall of the distributor; - the first and second flanges are fixed by the same screws or bolts to the sealing system; - the third and fourth flanges are fixed together by screws or bolts which are parallel to the axis and which are located on a circumference having a first diameter, the first wall of the second flange having an external diameter representing at least 90% of this first diameter, and preferably at least 100% of this first diameter; - the turbomachine further comprises a second annular sheet which includes an inner periphery interposed axially between the third and fourth flanges, and an outer periphery which is fixed to an upstream end of the internal wall of the distributor; - the sheet metal comprises a cylindrical wall which extends axially from the third flange to the first flange, and which surrounds an annular space formed between the first and third flanges;

[0036] — the sealing system is of the labyrinth type and cooperates with an external members of said portion of tree; - the outer periphery of the sheet metal includes a cylindrical rim which is radially interposed between a cylindrical rim of the upstream end of the internal wall of the distributor, and a cylindrical rim of one of the walls of the combustion chamber; - the first flange is flat and extends in a plane perpendicular to the axis;

[0037] — the first flange is partly frustoconical:

[0038] — the turbine is of the inverted type;

[0039] — the distributor and the turbine wheel are surrounded by the combustion chamber. Brief description of the figures

[0040] Other features and advantages of the invention will become apparent during the course of the Read the detailed description that follows, for an understanding of which refer to the attached drawings in which:

[0041] [Fig.1] [Fig.1] is a partial schematic axial cross-sectional view of an aircraft turbomachine;

[0042] [Fig.2] [Fig.2] is a larger-scale view of a detail of [Fig.1]; and

[0043] [Fig.3] [Fig.3] is a view similar to that of [Fig.2] and illustrates a method of application of the present invention. Detailed description of the invention

[0044] Figures 1 and 2 have already been described above.

[0045] Fig. 1 can be considered as illustrating the general context of the invention which relates to a turbomachine 10 for an aircraft.

[0046] As in this [Fig.1], the turbomachine 10 according to the invention conventionally comprises at least one compressor 12, an annular combustion chamber 14 and at least one turbine 16.

[0047] In the example shown, the turbomachine 10 comprises two successive compressors 12, which are therefore mounted one after the other and are both of the centrifugal type. This configuration is not, however, limiting; the compressors could successively be an axial compressor and a centrifugal compressor, for example.

[0048] The compressors 12 have an annular shape and are coaxial and centered on an axis A which is the longitudinal axis of the turbomachine 10. Each compressor 12, 14 comprises a stator and a bladed rotor, called a wheel 18, which rotates inside the stator and around the axis A.

[0049] Each compressor 12 comprises an inlet oriented axially upstream and an outlet oriented radially outwards with respect to axis A. The terms upstream and downstream here refer to the general flow of air and gas in the turbomachine 10.

[0050] A first annular rectifier-diffuser system 26 is mounted at the outlet of the first centrifugal compressor 12 to supply the second centrifugal compressor 12, and a second annular rectifier-diffuser system 28 is mounted at the outlet of the second centrifugal compressor 12 to supply the combustion chamber 14.

[0051] The combustion chamber 14 is as described above with reference to [Fig. 1],

[0052] The turbine 16 is at least partly located radially inside the chamber 14 and includes an annular distributor 36 and a wheel 22 located downstream of the distributor 36. The distributor 36 and the wheel 22 are both bladed and therefore include blades 41, 46, as described above.

[0053] The distributor 36 comprises two annular walls, respectively internal 38 and external 40, connected respectively to the annular walls 30, 32 of the chamber 14.

[0054] In the example shown in [Fig.3], the outer wall 40 of the distributor 36 is formed in one piece with the inner wall 30 of the chamber 14.

[0055] In the example shown in [Fig.3], the inner wall 38 of the distributor 36 includes an annular groove 70 which is oriented axially upstream and which receives a cylindrical rim 72 of the outer wall 32 of the chamber 14.

[0056] The platform 44 of the wheel 22 extends in the axial continuation of the inner wall 38 of the distributor 36. This inner wall 38 includes an annular flange 60 which extends radially inwards.

[0057] The outer wall 40 of the distributor 36 is axially supported by its downstream end on the sealing ring 42. The support plane is referenced PI in [Fig.3].

[0058] An annular sealing ring 73, for example with segment(s), can be interposed radially between the sealing ring 42 and the outer wall 40 of the distributor 36, and more particularly between the downstream end of the sealing ring 42 and the upstream end of the outer wall 40 of the distributor 36, as in the example shown.

[0059] Between the second centrifugal compressor 12 and the wheel 22 is mounted an annular sealing system 48 which aims to limit gas leakage axially along and outside the portion of shaft 24. This sealing system 48 surrounds with a small radial clearance the portion of shaft 24 which connects the wheel 22 to the impeller of the centrifugal compressor 12.

[0060] In the example shown in [Fig.3], the shaft portion 24 includes external annular blades 74 which can cooperate with an abradable internal coating of the sealing system 48 for example.

[0061] The sealing system 48 is part of a stator of the turbomachine 10, and is connected to the rectifier-diffuser system 28 on the one hand, and to the distributor 36 on the other hand.

[0062] The sealing system 48 is connected by a first annular flange 50 to the internal wall 38 of the distributor 36, and on the other hand by a second annular flange 52 to the rectifier-diffuser system 28.

[0063] The second flange 52 includes on its internal periphery a first internal annular flange 54 for fixing to the sealing system 48 by means of screws or nuts 62.

[0064] According to the invention, the second flange 52 comprises an annular wall 76 which is directly connected to this first flange 54 and which extends perpendicularly to the axis A.

[0065] The wall 74 has a radial height or dimension H1 greater than or equal to a radial height or dimension H2 of the flange 54, which gives the flange 52 flexibility and therefore an elastic deformation capacity in operation.

[0066] Advantageously, the wall 76 and the flange 54 extend in the same plane P2 perpendicular to the axis A. The wall 76 thus extends radially outwards in the extension of flange 54.

[0067] The wall 76 has a thickness or axial dimension El less than that E2 of the flange 54, which also contributes to its flexibility.

[0068] In the example shown, the wall 76 is connected to the rectifier-diffuser system 28 by a second annular wall 78 of the second flange 52, which has a truncated conical shape here flared upstream.

[0069] The flange 52 can be formed in one piece with a part of the rectifier-diffuser system 28, so the outer periphery of the flange 52 can be fully connected or made of material with the inner periphery of this part of the system 28.

[0070] A first annular plate 80 can be carried by the second flange 52 and be axially interposed between the impeller 18 of the centrifugal compressor 12 and the second flange 52.

[0071] For example, this first sheet 80 has its outer periphery which is fixed to the flange 52, at the level of its junction with the rectifier-diffuser system 28, and its inner periphery which is fixed to the flange 52, at the level of the junction between its inner flange 54 and its first wall 76.

[0072] The outer periphery of the first sheet 80 can be engaged in an annular groove 82 of the second flange 82, which opens radially inwards, as in the example shown.

[0073] In a similar manner, the inner periphery of the sheet metal 80 can be engaged in an annular groove 84 of the second flange 52 which opens radially outwards, as in the example shown.

[0074] The first sheet 80 can extend at least in part along a downstream radial face 18a of the impeller 18 of the centrifugal compressor 12 and define with the flange 52 an annular cavity 86. This cavity 86 makes it possible to thermally protect the impeller 18 from the high temperatures which prevail at the level of the chamber 14, and also makes it possible to limit the annular space directly downstream of the downstream face 18a, which is an area conducive to air recirculations and therefore likely to reduce the performance of the turbomachine.

[0075] With regard to the first flange 50, it may include at its inner periphery a second annular flange 56 for fixing to the sealing system 48, and at its outer periphery a third annular flange 58 for fixing to the flange 60 of the inner wall 38 of the distributor 36.

[0076] The flanges 54 and 56 can be fixed by the same screws or bolts 62 to the sealing system 48. In the example shown, the sealing system 48 is axially interposed between the flanges 54, 56 which include axial bearing faces on the sealing system 48. The screws or bolts 62 are parallel to the axis A.

[0077] The flanges 58, 60 can be fixed together by screws or bolts 64 which are parallel to the axis A and which are located on a circumference Cl having a first diameter Dl.

[0078] The wall 76 of the second flange 52 preferably has an external diameter D2 representing at least 90% of this first diameter Dl, and preferably at least 100% of this first diameter Dl, as in the example shown.

[0079] A second annular sheet 88 can be mounted around the sealing system 48.

[0080] This second sheet 88 can include an internal periphery interposed axially between the flanges 58, 60, and an external periphery which is fixed to an upstream end of the internal wall 38 of the distributor 36.

[0081] In the example shown, the sheet 88 includes a cylindrical wall 88a which extends axially from the flange 58 to the flange 54, and which surrounds an annular space 90 formed between these flanges 58, 54. This space 90 provides thermal protection for the sealing system 48 from the high temperatures prevailing at the level of the chamber 14.

[0082] In the example shown, the outer periphery of the sheet metal 88 includes a cylindrical rim 92 which is engaged in the groove 70, and which is radially interposed between a cylindrical rim 94 of the upstream end of the internal wall 38 of the distributor 36, and the cylindrical rim 72 of the wall 32 of the chamber 1.

[0083] As can be seen in [Fig.3], the first flange 50 is advantageously planar and extends in a plane P3 perpendicular to the axis A, which also gives this flange 50 some flexibility. Alternatively, it could have at least partly a frustoconical shape.

[0084] In general, the invention makes it possible to reduce the hyperstaticity of the aforementioned loop illustrated in [Fig.1] in dotted lines, and to increase the lifespan of the parts of this loop.

Claims

Demands

1. Turbomachine (10) for an aircraft, comprising: - a centrifugal compressor (12) extending about an axis (A), - a rectifier-diffuser assembly (28) extending about the axis (A) and mounted at the outlet of the centrifugal compressor (12), - an annular combustion chamber (14) extending about the axis (A), this combustion chamber (14) having two annular walls, respectively internal (30) and external (32), which define between them an annular combustion chamber (34), - an annular turbine distributor (36) extending about the axis (A) and mounted at the outlet of the combustion chamber (14), this distributor (36) having two annular walls, respectively internal (38) and external (40), connected respectively to the annular walls (30, 32) of the combustion chamber (12), - a turbine wheel (22) extending about the shaft (A) and mounted at the output of the turbine distributor (36),the wheel (22) being surrounded by a sealing ring (42) which includes an upstream axial end on which the outer wall (40) of the distributor (36) is axially supported, the wheel (22) having a disc which is connected to a wheel (18) of the centrifugal compressor (12) by a portion of shaft (24) extending around the axis (A), and - an annular sealing system (48) extending around the axis (A) and around the portion of shaft (24), this sealing system (48) being connected by a first annular flange (50) to the inner wall (38) of the distributor (36) and on the other hand by a second annular flange (52) to the rectifier-diffuser system (48), the second flange (52) having a first internal annular flange (54) fixed by screws or bolts (62) to the sealing system (48), characterized in that the second flange (52) comprises an annular wall (76) which is directly connected to the first flange (54) and which extends perpendicularly to the axis (A),this wall (76) having a radial height or dimension (H2) greater than or equal to a radial height or dimension (Hl) of the first flange (54).

2. Turbomachine (10) according to claim 1, wherein the first wall (76) and the first flange (54) of the second flange (52) extend in the same plane (P2) perpendicular to the axis (A).

3. Turbomachine (10) according to claim 1 or 2, wherein the first wall (76) has a thickness or axial dimension (El) less than that (E2) of the first flange (54) of the second flange (52).

4. Turbomachine (10) according to any one of the preceding claims, wherein the first wall (76) of the second flange (52) is connected to the rectifier-diffuser system (28) by a second annular wall (78) of the second flange (52), this second annular wall (78) having a frustoconical shape.

5. Turbomachine (10) according to any one of the preceding claims, further comprising a first annular plate (80) which is carried by the second flange (52) and which is axially interposed between the impeller (18) of the centrifugal compressor (12) and the second flange (52).

6. Turbomachine (10) according to claim 5, wherein the first sheet (80) has its outer periphery which is fixed to the flange (52), at the level of its junction with the straightener-diffuser system (28), and its inner periphery which is fixed to the flange (52), at the level of the junction between its first flange (54) and its first wall (76).

7. Turbomachine (10) according to claim 6, wherein the outer periphery of the first sheet (80) is engaged in an annular groove (82) of the second flange (52), which opens radially inwards, and the inner periphery of the sheet (80) is engaged in an annular groove (84) of the second flange (52) which opens radially outwards.

8. Turbomachine (10) according to any one of claims 5 to 7, wherein the first sheet (80) extends at least partly along a downstream radial face (18a) of the impeller (18) of the centrifugal compressor (12) and defines with the flange (52) an annular cavity (86).

9. Turbomachine (10) according to any one of the preceding claims, wherein the first flange (50) comprises at its inner periphery a second annular flange (56) for attachment to the sealing system (48), and at its outer periphery a third annular flange (58) for attachment to a fourth annular flange (60) of the inner wall (40) of the distributor (36).

10. Turbomachine (10) according to claim 9, wherein the first and second flanges (54, 56) are fixed by the same screws or bolts (62) to the sealing system (48).

11. Turbomachine (10) according to claim 9 or 10, wherein the third and fourth flanges (58, 60) are fixed to each other by screws or bolts (64) which are parallel to the axis (A) and which are located on a circumference (Cl) having a first diameter (Dl), the first wall (76) of the second flange (52) having an external diameter (D2) representing at least 90% of this first diameter (Dl), and preferably at least 100% of this first diameter (Dl).

12. Turbomachine (10) according to any one of claims 9 to 11, further comprising a second annular plate (88) which includes an inner periphery intercalated axially between the third and fourth flanges (58, 60), and an outer periphery which is fixed to an upstream end of the inner wall (38) of the distributor (36).

13. Turbomachine (10) according to claim 12, wherein the sheet (88) comprises a cylindrical wall (88a) which extends axially from the third flange (58) to the first flange (54), and which surrounds an annular space (90) formed between the first and third flanges (54, 58).

14. Turbomachine (10) according to claim 12 or 13, wherein the outer periphery of the sheet (88) comprises a cylindrical rim (92) which is radially intercalated between a cylindrical rim (94) of the upstream end of the inner wall (38) of the distributor (36), and a cylindrical rim (72) of one of the walls (32) of the combustion chamber (14).

15. Turbomachine (10) according to any one of the preceding claims, wherein the first flange (50) is planar and extends in a plane (P3) perpendicular to the axis (A).

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