Turbine engine for an aircraft

Abstract

Turbine engine (10) for an aircraft, comprising: - a centrifugal compressor (12), - a flow straightener-diffuser assembly (28), - an annular combustion chamber (14), - a turbine annular distributor (36), - a turbine wheel (22), and - an annular sealing system (48) connected to the distributor (36) by a first annular flange (50) and, on the other side, to the flow straightener-diffuser system (48) by a second annular flange (52), characterized in that the second flange (52) comprises an annular wall (76) which extends perpendicularly to the axis (A) and which gives this flange a certain flexibility.

Description

[0001] DESCRIPTION

[0002] TITLE: TURBOMACHINE FOR AN AIRCRAFT

[0003] Technical field of the invention

[0004] The present invention relates to a turbomachine for an aircraft.

[0005] Technical background

[0006] The technical background includes, in particular, documents US-B1-11,773,773, US-A1-2022 / 213808 and US-B2-8,087,249.

[0007] An aircraft turbomachine comprises a gas generator comprising, 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 the compressor rotor via a common shaft.

[0008] A turbomachine can be equipped with one or more bodies each comprising a compressor rotor connected by a shaft to a turbine rotor.

[0009] There are also turbomachines where a free turbine is mounted downstream of the turbomachine body(s). A turbine is free to the extent that its rotor is not connected by a shaft to a compressor rotor.

[0010] 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).

[0011] Figure 1 very schematically represents an aircraft turbomachine 10.

[0012] 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. 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 shaft portion 20.

[0013] The rotor of the turbine 16 is formed by a wheel 22 which is connected to the impellers 18 of the compressors 12 by another shaft portion 24. The wheel 22, the impellers 18 and the shaft portions 20, 24 form a rotating body of the turbomachine.

[0014] 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.

[0015] The combustion chamber 14 is here of the inverted type and comprises 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.

[0016] The chamber 14 comprises two annular walls, respectively internal 30 and external 32, which define between them an annular combustion hearth 34. At least a portion of the compressed air which leaves the rectifier-diffuser system 28 enters the combustion chamber 14.

[0017] 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 outer 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 inner 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.

[0018] The turbine 16 is at least partly located radially inside the chamber 14 and comprises an annular distributor 36 and the aforementioned wheel 22. The distributor 36 is interposed axially 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. The distributor 36 is bladed and comprises vanes 41 extending between its internal 38 and external 40 walls.

[0019] As can be seen more clearly in FIG. 2, the downstream end of the outer wall 40 of the distributor 36 bears axially on an upstream end of a sealing ring 42 which surrounds the wheel 22. Furthermore, the wheel comprises an annular platform 44 which extends in the axial extension of the inner wall 38 of the distributor 36. The wheel 22 further comprises blades 46 which extend radially outwards from the platform 44 to the sealing ring 42 and which are separated from this ring by small radial clearances. The wheel 22 may be of the single-piece type or its blades 46 may be attached and mounted on a disc of the wheel 22.

[0020] Between the second centrifugal compressor 12 and the wheel 22 is mounted an annular sealing system 48 which aims to limit gas leaks axially along and outside the shaft portion 24. This sealing system 48 therefore surrounds with a small radial clearance the shaft portion 24 which connects the wheel 22 to the impeller of the centrifugal compressor 12.

[0021] 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.

[0022] 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.

[0023] The second flange 52 comprises an internal annular flange 54 for fixing to an internal annular flange 56 of the first flange 50, and this first flange 50 comprises 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.

[0024] The axial support of the distributor 36 on the sealing ring 42 ensures precise axial positioning of this distributor and makes it possible to improve the performance of the turbine 16 in this area. However, this configuration generates a hyperstatic loop (shown in dotted lines in Figure 1) which results in stresses in the parts. Indeed, in order to ensure axial support between the distributor 36 on the sealing ring 42, a pre-tightening is put in place in the hyperstatic loop. This pre-tightening generates a level of stresses in the loop which causes mechanical stresses in the components.

[0025] A solution to this problem could consist of integrating “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 greater radial size of these parts. This solution would therefore not always be usable, particularly in small turbomachines.

[0026] The present invention provides a solution to at least some of the problems discussed above.

[0027] Summary of the invention

[0028] The invention relates to an aircraft turbomachine, comprising:

[0029] - a centrifugal compressor extending around an axis,

[0030] - a rectifier-diffuser assembly extending around the axis and mounted at the outlet of the centrifugal compressor,

[0031] - an annular combustion chamber extending around the axis, this combustion chamber comprising two annular walls, respectively internal and external, which define between them an annular combustion hearth,

[0032] - 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,

[0033] - a turbine wheel extending around the axis and mounted at the outlet of the turbine distributor, the wheel being surrounded by a sealing ring which comprises an upstream axial end on 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 shaft portion extending around the axis, and

[0034] - an annular sealing system extending around the axis and around the shaft portion, 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, characterized in that the second flange comprises an annular wall which is directly connected to the first flange and which extends perpendicular 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.

[0035] The invention thus proposes to confer flexibility to the second flange. This flexibility is obtained by the particular shape of the second flange which comprises a radial wall of relatively large radial dimension. Unlike a truncated or curved wall, a radial wall makes it possible in this environment to confer greater flexibility to the second flange and to reduce the hyperstaticism of the aforementioned loop. The components crossed by the loop are thus less mechanically constrained.

[0036] In the present application, "flexibility" means the fact that a part has a capacity for elastic deformation, in particular in bending.

[0037] The turbomachine according to the invention may comprise one or more of the following steps or characteristics, considered independently of one another or in combination with one another:

[0038] - the first wall and the first flange of the second plate extend in the same plane perpendicular to the axis;

[0039] - the first wall has a thickness or axial dimension less than that of the first flange of the second plate;

[0040] - 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 cone shape;

[0041] - The turbomachine further comprises a first annular sheet which is carried by the second flange and which is axially interposed between the impeller of the centrifugal compressor and the second flange;

[0042] - the first sheet has its external periphery which is fixed to the flange, at its junction with the rectifier-diffuser system, and its internal periphery which is fixed to the flange, at the junction between its first flange and its first wall; - the external periphery of the first sheet is engaged in an annular groove of the second flange, which opens radially inwards, and the internal periphery of the sheet is engaged in an annular groove of the second flange which opens radially outwards;

[0043] - the first sheet extends at least partly along a downstream radial face of the impeller of the centrifugal compressor and defines with the flange an annular cavity;

[0044] -- the second flange is formed from a single piece with at least part of the rectifier-diffuser system;

[0045] - the first flange comprises at its internal periphery a second annular flange for fixing to the sealing system, and at its external periphery a third annular flange for fixing to a fourth annular flange of the internal wall of the distributor;

[0046] - the first and second flanges are fixed by the same screws or bolts to the sealing system;

[0047] - 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;

[0048] - the turbomachine further comprises a second annular sheet which comprises an internal periphery axially interposed between the third and fourth flanges, and an external periphery which is fixed to an upstream end of the internal wall of the distributor;

[0049] - 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;

[0050] -- the sealing system is of the labyrinth type and cooperates with external annular wipers of said shaft portion;

[0051] - the external periphery of the sheet metal comprises a cylindrical rim which is interposed radially 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;

[0052] - the first flange is flat and extends in a plane perpendicular to the axis; -- the first flange is partly truncated:

[0053] -- the turbine is of the reverse type;

[0054] -- the distributor and turbine wheel are surrounded by the combustion chamber.

[0055] Brief description of the figures

[0056] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0057] [Fig.1] Figure 1 is a partial schematic view in axial section of an aircraft turbomachine;

[0058] [Fig.2] Figure 2 is an enlarged view of a detail of Figure 1; and

[0059] [Fig.3] Figure 3 is a view similar to that of Figure 2 and illustrates an embodiment of the present invention.

[0060] Detailed description of the invention

[0061] Figures 1 and 2 have already been described in the above.

[0062] Figure 1 may be considered as illustrating the general context of the invention which relates to a turbomachine 10 for an aircraft.

[0063] As in this figure 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.

[0064] In the example shown, the turbomachine 10 comprises two successive compressors 12 which are therefore mounted one after the other and which are both of the centrifugal type. This configuration is however not limiting, the compressors being able to be successively an axial compressor and a centrifugal compressor for example.

[0065] 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 impeller 18, which rotates inside the stator and around the axis A.

[0066] Each compressor 12 comprises an inlet oriented axially upstream and an outlet oriented radially outwards with respect to the axis A. The expressions upstream and downstream here refer to the general flow of air and gases in the turbomachine 10.

[0067] 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.

[0068] The combustion chamber 14 is as described in the foregoing with reference to FIG. 1.

[0069] The turbine 16 is at least partly located radially inside the chamber 14 and comprises 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 comprise vanes 41, 46, as described above.

[0070] 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.

[0071] In the example shown in Figure 3, the external wall 40 of the distributor 36 is formed in a single piece with the internal wall 30 of the chamber 14.

[0072] In the example shown in Figure 3, the internal wall 38 of the distributor 36 comprises an annular groove 70 which is oriented axially upstream and which receives a cylindrical rim 72 of the external wall 32 of the chamber 14.

[0073] The platform 44 of the wheel 22 extends in the axial extension of the internal wall 38 of the distributor 36. This internal wall 38 comprises an annular flange 60 which extends radially inwards.

[0074] The external wall 40 of the distributor 36 is axially supported by its downstream end on the sealing ring 42. The support plane is referenced P1 in figure 3.

[0075] An annular sealing joint 73, for example with segment(s), may be interposed radially between the sealing ring 42 and the external wall 40 of the distributor 36, and more particularly between the downstream end of the sealing ring 42 and the upstream end of the external wall 40 of the distributor 36, as in the example shown.

[0076] Between the second centrifugal compressor 12 and the wheel 22 is mounted an annular sealing system 48 which aims to limit gas leaks axially along and outside the shaft portion 24. This sealing system 48 surrounds with a small radial clearance the shaft portion 24 which connects the wheel 22 to the impeller of the centrifugal compressor 12.

[0077] In the example shown in Figure 3, the shaft portion 24 comprises external annular wipers 74 which can cooperate with an abradable internal coating of the sealing system 48 for example.

[0078] 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.

[0079] 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.

[0080] The second flange 52 comprises at its internal periphery a first internal annular flange 54 for fixing to the sealing system 48 by screws or nuts 62.

[0081] 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 perpendicular to the axis A.

[0082] The wall 74 has a height or radial dimension H1 greater than or equal to a height or radial dimension H2 of the flange 54, which gives the plate 52 flexibility and therefore a capacity for elastic deformation during operation.

[0083] 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 the flange 54.

[0084] The wall 76 has a thickness or axial dimension E1 less than that E2 of the flange 54, which also contributes to its flexibility.

[0085] 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 cone shape here flared upstream.

[0086] The flange 52 may be formed in a single piece with a part of the rectifier-diffuser system 28, so the external periphery of the flange 52 may be integrally connected or made of the same material as the internal periphery of this part of the system 28. A first annular sheet 80 may 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.

[0087] For example, this first sheet 80 has its external periphery which is fixed to the flange 52, at the level of its junction with the rectifier-diffuser system 28, and its internal periphery which is fixed to the flange 52, at the level of the junction between its internal flange 54 and its first wall 76.

[0088] 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.

[0089] In a similar manner, the internal periphery of the sheet 80 can be engaged in an annular groove 84 of the second flange 52 which opens radially outwards, as in the example shown.

[0090] The first sheet 80 may 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 heat which prevails 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 recirculation and therefore likely to reduce the performance of the turbomachine.

[0091] As regards the first flange 50, it may comprise at its internal periphery a second annular flange 56 for fixing to the sealing system 48, and at its external periphery a third annular flange 58 for fixing to the flange 60 of the internal wall 38 of the distributor 36.

[0092] 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 interposed axially between the flanges 54, 56 which comprise axial bearing faces on the sealing system 48. The screws or bolts 62 are parallel to the axis A.

[0093] The flanges 58, 60 may be fixed together by screws or bolts 64 which are parallel to the axis A and which are located on a circumference C1 having a first diameter D1. The wall 76 of the second flange 52 preferably has an external diameter D2 representing at least 90% of this first diameter D1, and preferably at least 100% of this first diameter D1, as in the example shown.

[0094] A second annular sheet 88 may be mounted around the sealing system 48.

[0095] This second sheet 88 may comprise an internal periphery axially interposed 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.

[0096] In the example shown, the sheet 88 comprises 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 makes it possible to thermally protect the sealing system 48 from the high heat which prevails at the level of the chamber 14.

[0097] In the example shown, the external periphery of the sheet 88 comprises a cylindrical rim 92 which is engaged in the groove 70, and which is interposed radially 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.

[0098] As can be seen in Figure 3, the first flange 50 is advantageously flat and extends in a plane P3 perpendicular to the axis A, which also gives a certain flexibility to this flange 50. As a variant, it could have at least partly a truncated cone shape.

[0099] Generally speaking, the invention makes it possible to reduce the hyperstatic nature of the aforementioned loop illustrated in Figure 1 in dotted lines, and to increase the service life of the parts of this loop.

Claims

CLAIMS 1. Turbomachine (10) for an aircraft, comprising: - a centrifugal compressor (12) extending around an axis (A), - a rectifier-diffuser assembly (28) extending around the axis (A) and mounted at the outlet of the centrifugal compressor (12), - an annular combustion chamber (14) extending around the axis (A), this combustion chamber (14) comprising two annular walls, respectively internal (30) and external (32), which define between them an annular combustion hearth (34), - an annular turbine distributor (36) extending around the axis (A) and mounted at the outlet of the combustion chamber (14), this distributor (36) comprising 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 around the axis (A) and mounted at the outlet of the turbine distributor (36), the wheel (22) being surrounded by a sealing ring (42) which comprises an upstream axial end on which the external wall (40) of the distributor (36) is in axial support, the wheel (22) comprising a disc which is connected to an impeller (18) of the centrifugal compressor (12) by a shaft portion (24) extending around the axis (A), and - an annular sealing system (48) extending around the axis (A) and around the shaft portion (24), this sealing system (48) being 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 (48), the second flange (52) comprising 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 perpendicular to the axis (A), this wall (76) having a height or radial dimension (H2) greater than or equal to a height or radial dimension (H1) of the first flange (54).

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

3. Turbomachine (10) according to claim 1 or 2, in which the first wall (76) has a thickness or axial dimension (E1) less than that (E2) of the first flange (54) of the second end plate (52).

4. Turbomachine (10) according to one of the preceding claims, in which 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 truncated cone shape.

5. Turbomachine (10) according to one of the preceding claims, further comprising a first annular sheet (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, in which the first sheet (80) has its external periphery which is fixed to the flange (52), at its junction with the rectifier-diffuser system (28), and its internal periphery which is fixed to the flange (52), at the junction between its first flange (54) and its first wall (76).

7. Turbomachine (10) according to claim 6, in which the external periphery of the first sheet (80) is engaged in an annular groove (82) of the second flange (52), which opens radially inwards, and the internal 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 one of claims 5 to 7, in which 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 one of the preceding claims, in which the first flange (50) comprises at its internal periphery a second annular flange (56) for fixing to the sealing system (48), and at its external periphery a third annular flange (58) for fixing to a fourth annular flange (60) of the internal wall (40) of the distributor (36).

10. Turbomachine (10) according to claim 9, in which 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, in which the third and fourth flanges (58, 60) are fixed together by screws or bolts (64) which are parallel to the axis (A) and which are located on a circumference (C1) having a first diameter (D1), the first wall (76) of the second flange (52) having an external diameter (D2) representing at least 90% of this first diameter (D1), and preferably at least 100% of this first diameter (D1).

12. Turbomachine (10) according to one of claims 9 to 11, further comprising a second annular sheet (88) which comprises an internal periphery axially interposed between the third and fourth flanges (58, 60), and an external periphery which is fixed to an upstream end of the internal wall (38) of the distributor (36).

13. Turbomachine (10) according to claim 12, in which 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, in which the external periphery of the sheet metal (88) comprises a cylindrical rim (92) which is interposed radially between a cylindrical rim (94) of the upstream end of the internal 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 one of the preceding claims, in which the first flange (50) is flat and extends in a plane (P3) perpendicular to the axis (A).

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