Turbomachine assembly comprising a half-shell casing bearing variable-pitch inlet stator vanes

Abstract

The present invention relates to an assembly (12) for a turbomachine, comprising: - an outer casing (15) made of half-shells; - an inner casing (14); - a plurality of guide vanes (13) mounted between the outer casing (15) and the inner casing (14), - a structural casing comprising a flange (23) which is radially inside the inner casing (14); and - a system (24) for blocking the inner casing (14) on the structural casing, comprising a generally annular tab (25) fixed to one of the inner casing (14) and the structural casing and a complementary chute (26) fixed to the other of the inner casing (14) and the structural casing, the chute (26) being configured to receive the tab (25) and to block it along the axis (X) with respect to the structural casing.

Description

[0001] DESCRIPTION

[0002] TITLE: Turbomachine assembly comprising a half-shell casing carrying variable-pitch inlet stator blades

[0003] FIELD OF THE INVENTION

[0004] The invention relates generally to the field of turbomachines including in particular fixed inlet guide vanes with variable pitch, and more particularly to the maintenance and inspection of such turbomachines.

[0005] STATE OF THE ART

[0006] A bypass turbomachine generally comprises, from upstream to downstream in the direction of gas flow, a fan, a primary flow annular space and a secondary flow annular space which extends around the primary flow. The air mass drawn in by the fan is therefore divided into a primary flow, which circulates in the primary flow space, and a secondary flow, which is concentric with the primary flow and circulates in the secondary flow space.

[0007] The turbomachine may also include a variable-pitch inlet guide vane (or IGV) wheel located immediately upstream of a booster (or low-pressure compressor), at the inlet to the primary flow space. The IGVs are conventionally mounted by individually mounting each IGV in an external casing of the turbomachine and fixing this external casing to a structural casing, typically using a flange and nuts. The internal part of the turbomachine is not yet in place. Upstream and downstream parts of the internal casing of the turbomachine are then put in place on either side of the IGV root in order to reconstitute a complete internal casing "supporting" the IGVs radially inside. This entire internal casing is then fixed to the adjacent structural casing, typically an intermediate casing (or inter-compressor casing), by means of screws.

[0008] Thus, to access the IGVs or inspect the rotor blades downstream of the IGV (usually a booster stage), it is necessary to separate the structural casing from the entire rotor stage that follows it, in particular to be able to access the screws of the internal casing. However, such disassembly is long and difficult, particularly in engines including a reduction mechanism between the low pressure shaft and the fan, because their architecture is very complex.

[0009] STATEMENT OF THE INVENTION

[0010] An aim of the invention is to remedy the aforementioned drawbacks, by proposing a turbomachine comprising a row of IGVs and, optionally, a reduction mechanism between the low pressure shaft and the fan, which can be easily disassembled and reassembled, in particular during a maintenance or inspection operation in order to optimize operational costs.

[0011] For this purpose, according to a first aspect of the invention, an assembly for a turbomachine is proposed, comprising:

[0012] - an external half-shell casing comprising a first and a second hemispherical external shell;

[0013] - an inner casing located radially inside the outer casing and comprising a first and a second hemispherical inner shell;

[0014] - a plurality of guide vanes mounted between the outer casing and the inner casing,

[0015] - a structural casing comprising a generally cylindrical flange located radially inside the internal casing and having a symmetry of revolution with respect to an axis; and

[0016] - a system for locking the internal casing on the structural casing, the locking system comprising a generally annular tab fixed on one of the internal casing and the structural casing and a complementary chute fixed on the other of the internal casing and the structural casing, the chute being configured to receive the tab and lock it along the axis relative to the structural casing.

[0017] Some preferred but non-limiting features of the assembly for a turbomachine according to the first aspect are the following, taken individually or in combination:

[0018] - the leg is monolithic with the internal casing and the chute is monolithic with the structural casing;

[0019] - the chute has a downstream side and an upstream side separated by a bottom, the downstream side being inclined relative to a plane normal to the axis and the tab has an inclined downstream face configured to bear against the downstream side of the chute;

[0020] - the leg has an upstream face configured to bear against an upstream side of the gutter, the upstream side and the upstream face each being parallel to a plane normal to the axis;

[0021] - the upstream face has an external radial portion configured to bear against the upstream face of the chute and an internal radial portion forming an annular clearance extending at a distance from the external radial portion;

[0022] - the chute further comprises a bottom connected to the upstream side and / or to the downstream side by a curved surface; and / or

[0023] - the inner casing further comprises a first and a second hemispherical downstream inner shroud extending immediately downstream of the first and second inner shrouds, a root of the guide vanes being mounted between the first and second inner shrouds and the first and second downstream inner shrouds. According to a second aspect, the invention proposes a turbomachine comprising an assembly according to the first aspect.

[0024] Some preferred but non-limiting features of the turbomachine according to the second aspect are the following, taken individually or in combination:

[0025] - the turbomachine further comprises a rotor mounted immediately downstream of the assembly, for example a booster; and / or

[0026] - the turbomachine further comprises a turbine configured to drive a fan via a reduction mechanism, the turbine being further configured to drive the rotor.

[0027] According to a third aspect, the invention proposes an aircraft comprising at least one turbomachine according to the second aspect.

[0028] DESCRIPTION OF FIGURES

[0029] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0030] Figure 1 is an axial sectional view of a turbomachine assembly according to one embodiment of the invention;

[0031] Figure 2 is a partial perspective view of the turbomachine assembly of Figure 1; and

[0032] Figure 3 is a detailed view of the locking system of the turbomachine assembly of Figure 1.

[0033] Figure 4 is a front view of the half-shells of the turbomachine assembly of Figure 1 being assembled with the structural casing.

[0034] Figure 5 is a simplified sectional view of an example of a turbomachine which may comprise a turbomachine assembly according to the invention.

[0035] Throughout the figures, similar elements have identical references.

[0036] DETAILED DESCRIPTION OF THE INVENTION

[0037] A double-flow turbomachine 1 comprises, as indicated above, a fan 2, an annular primary flow space and an annular secondary flow space around the primary flow. The fan 2 (or propeller) can be shrouded and housed in a fan casing or in an unshrouded variant of the USF type (acronym for Unducted Single Fan). The fan blades can be fixed or have a variable pitch, the pitch being adjusted according to the flight phases by a pitch change mechanism.

[0038] The primary flow space passes through a primary body comprising one or more compressor stages, for example a low-pressure compressor (or booster 3) and a high-pressure compressor 4, a combustion chamber, one or more turbine stages, for example a high-pressure turbine 5 and a low-pressure turbine 6, and a gas exhaust nozzle. Typically, the high-pressure turbine 5 rotates the high-pressure compressor 4 via a first shaft, called the high-pressure shaft 9, while the low-pressure turbine 6 rotates the booster 3 and the fan 2 via a second shaft, called the low-pressure shaft 8.

[0039] In order to improve the propulsive efficiency of the turbomachine 1 and to reduce its specific consumption as well as the noise emitted by the fan 2, turbomachines 1 have been proposed having a high bypass ratio, that is to say a ratio between the flow rate of the secondary flow and that of the primary flow. By high bypass ratio, we will understand here a bypass ratio greater than 10, for example between 12 and 18. To achieve such bypass ratios, the fan 2 is decoupled from the low pressure turbine 6, thus making it possible to independently optimize their respective rotational speed. For example, the decoupling can be achieved using a reducer such as an epicyclic or planetary reduction mechanism 7, placed between the upstream end of the low pressure shaft 8 and the fan 2.The fan 2 is then driven by the low pressure shaft 8 via the reduction mechanism 7 and an additional shaft, called the fan shaft 2, which is fixed between the reduction mechanism 7 and the disk of the fan 2. This decoupling thus makes it possible to reduce the rotational speed and the pressure ratio of the fan 2 and to increase the power extracted by the low pressure turbine 6.

[0040] In dual-flow turbomachines 1, a large part of the thrust is provided by the fan 2. The axial forces applied to the fan blades are transmitted by a thrust bearing to the fixed parts of the engine, then raised to the engine suspensions via the intermediate casing 10 (or inter-compressor casing).

[0041] In a turbomachine 1 comprising a reduction mechanism 7 between the low-pressure shaft 8 and the fan shaft 2, the path of the forces is arranged differently. Indeed, the engine comprises, in addition to the intermediate casing 10, an inlet casing 11 located between the fan 2 and the booster 3 in order to support the weight of the reduction mechanism 7 and the bearings. The inlet casing 11 is thus designed to directly support the reduction mechanism 7 and the bearings supporting the fan shaft. In such an architecture, the axial forces thus pass through the inlet casing 11 and the intermediate casing 10. The turbomachine 1 further comprises a fixed vane wheel 12 (stator) for inlet guide (IGV wheel 12) located immediately upstream of the booster 3, at the level of the inlet of the primary flow space.

[0042] The IGV wheel 12 comprises a plurality of IGVs 13, an outer casing 15 and an inner casing 14, the IGVs 13 being mounted between the inner casing 14 and the outer casing 15 via pivot connections 16. The outer casing 15 is a half-shell casing, that is to say that it comprises a first and a second hemispherical outer shell 17, 18 which are connected so as to form the outer casing 15. The inner casing 14 is also a half-shell casing and comprises two hemispherical upstream inner shells 19, 20 and two hemispherical downstream inner shells 21, 22 connected two by two so as to form an upstream shell and a downstream shell of the inner casing 14. The upstream shells and the downstream shells 21, 22 extend from on either side of the feet of the IGV 13 and are fixed together by mechanical connections, typically bolted connections.

[0043] Each hemispherical 19-22 ferrule is preferably monolithic.

[0044] The turbomachine 1 further comprises a structural casing 10, 11 comprising an annular flange 23 extending radially inside the inner casing 14. The structural casing 10, 11 may in particular correspond to the inlet casing 11 or to the intermediate casing 10, depending on the configuration of the turbomachine 1. In the example illustrated in FIGS. 1 to 4 for example, the flange 23 and the outer casing 14 are fixed to the inlet casing 10.

[0045] In the following, upstream and downstream are defined with respect to the normal flow direction of the gas through the turbomachine 1. Furthermore, the axis of revolution of the annular flange 23 of the structural casing 10, 11 is called the X axis. The axial direction corresponds to the direction of the X axis and a radial direction is a direction perpendicular to this X axis and passing through it. Unless otherwise specified, internal (respectively, interior) and external (respectively, exterior), respectively, are used with reference to a radial direction so that the internal part or face of an element is closer to the X axis than the external part or face of the same element. Finally, the term "structural casing" will designate a casing of the turbomachine 1 used for load transfer, that is to say through which forces, in particular axial and radial, pass (such as the loads of the loads of the bearings supporting the shafts to the suspensions of the turbomachine).This may be, for example, the intermediate casing 10 or, in the case of a turbomachine 1 comprising a reduction mechanism 7, the inlet casing 11 or the intermediate casing 10. On the other hand, the internal casing 14 and the external casing 15 both have a function of supporting the IGVs 13 and of delimiting the flow path within the IGV wheel 13. On the other hand, they do not form a structural casing within the meaning of the patent. The IGVs 13 are fixed in the sense that they are fixed in rotation relative to the inner casing 14 and the outer casing 15 around the X axis. The IGVs 13 are, on the other hand, variable-pitch and are mounted on the inner casing 14 and the outer casing 15 by means of pivot links 16 in order to be able to adjust their angle of incidence relative to the flow according to the flight phases of the turbomachine 1. The pitch axis of the IGVs 13 is substantially radial to the X axis.

[0046] For this purpose, the IGVs 13 each comprise a head and a foot fixed to the outer casing 15 and the inner casing 14, respectively, by means of pivot links 16 so as to allow the rotation of the IGVs 13 around their setting axis. The turbomachine 1 further comprises a control kinematics which can be mounted on the outer casing 15 and configured to control the setting angle of the corresponding pivot link 16 of the IGVs 13.

[0047] In order to fix the IGVs 13 on the structural casing 10, 11, the turbomachine 1 further comprises a locking system 24 of the internal casing 14 on the structural casing 10, 11 comprising a tab 25 fixed on one of the internal casing 14 and the structural casing 10, 11 and a complementary channel 26 fixed on the other of the internal casing 14 and the structural casing 10, 11. The channel 26 is configured to receive the tab 25 and block it axially (i.e. along the axis X) relative to the structural casing 10, 11.

[0048] The IGV wheel 13 is therefore formed of two parts or half-shells 13a, 13b, each half-shell 13a, 13b of the IGV wheel 13 comprising an outer shell 17, 18, an IGV assembly 13, an upstream inner shell 19, 20 and a downstream inner shell 21, 22. A first half-shell 13a of the IGV wheel 13 can then be mounted in the turbomachine 1 by placing the lug 25 in the chute 26, so as to axially block the half-shell relative to the structural casing 10, 11. The other half-shell 13b of the IGV wheel 13 can then be fixed in a similar manner, by placing the lug 25 in the corresponding chute 26. Then the two half-shells 13a, 13b can be secured by fixing their external shell 17, 18 to the structural casing 10, 11, for example using bolted connections.

[0049] The disassembly of the IGV wheel 13 can be carried out in a similar manner, by disassembling the external casing 15, for example by disengaging the bolted connections. It is then sufficient to remove the tab 25 from the corresponding chute 26 to separate the two half-shells 13a, 13b of the IGV wheel 13 from the structural casing 10, 11. This disassembly is particularly easy since it is not necessary to disassemble the fixing means placed at the level of the internal casing 14 which would otherwise be difficult to access.

[0050] In the following, the invention will be described in the case where the lug 25 is monolithic with the internal casing 14 and the chute 26 is integral with the structural casing 10, 11, typically monolithic with the flange 23. This embodiment in fact facilitates the mounting of the IGV wheel 13 on the structural casing 10, 11 and also ensures better radial retention of the IGV wheel 13. This is however not limiting, the lug 25 being able to be monolithic with the structural casing 10, 11 and the chute 26 monolithic with the internal casing 14.

[0051] The lug 25 is generally cylindrical around the axis X, preferably annular. The lug 25 being monolithic with the internal casing 14, it is made in two parts: a first part fixed on one of the upstream ferrules 19 and a second part fixed on the other of the upstream ferrules 20. Each part of the lug 25 can be substantially continuous around the axis X, or alternatively comprise disjointed ring sectors. For convenience, however, in the following we will refer to “the lug 25”, even if it is in several parts.

[0052] The chute 26 is of a complementary shape to the tab 25 and is generally cylindrical around the axis X. The chute 26 may be substantially continuous over its entire periphery or, as a variant, comprise separate chute sectors 26.

[0053] The tab 25 extends radially inward from the upstream internal ferrules 19, 20 of the internal casing 14. In one embodiment, the tab 25 extends from an upstream end of the upstream internal ferrules 19, 20. The chute 26 extends radially outward from the flange 23, opposite the tab 25.

[0054] The flange 23 may comprise an annular sheet metal fixed to the structural casing 10, 11 upstream of the internal casing 14, typically from a downstream end of the annular sheet metal. The chute 26 extends for example from a downstream radial end of the flange 23.

[0055] The chute 26 comprises a downstream face 27, an upstream face 28 and a bottom 29 connecting the downstream face 27 and the upstream face 28. The side of the chute 26 which is opposite the bottom 29 is open in order to allow the introduction of the tab 25 into the chute 26. The bottom 29 is arranged radially inside relative to the upstream and downstream faces 28, 27 of the chute 26. The tab 25 for its part has a downstream face 30 configured to abut against the downstream face 27, an upstream face 31 configured to abut against the upstream face 28, and a top 32 connecting the downstream face 30 and the upstream face 31 and configured to extend opposite the bottom 29 of the chute 26. The tab 25 and the chute 26 are dimensioned so that the top 32 of the tab 25 remains at a distance from the bottom 29 of the chute 26 and therefore does not come into contact with the chute 26, even when the tab 25 is engaged in the chute 26.

[0056] In order to effectively block the internal casing 14 relative to the structural casing 10, 11 in the axial direction, the downstream face 27 and the downstream face 30 are inclined relative to a plane P normal to the axis X passing through the center of the chute 26. In particular, the downstream face 27 is inclined in the direction of the bottom 29 so as to guide the downstream face 30 towards the bottom 29 and the upstream face 31 of the chute 26. The angle formed between the downstream face 27 and the plane P normal to the axis X can be between 15° and 45°.

[0057] The upstream face 28 of the chute 26 and the upstream face 31 of the tab 25 are substantially parallel to the plane P normal to the axis X. They are therefore radial to the axis X.

[0058] The tab 25 is then wedged into the chute 26, which makes it possible to effectively block the internal casing 14 relative to the structural casing 10, 11 in the axial direction. This axial support is particularly relevant in the case of pumping or adjustment of the dimensions, insofar as it ensures axial holding of the IGV wheel 13 despite the application of axial forces to the IGV wheel 13. The radial blocking is done on the one hand by the stop formed by the downstream face 27 and on the other hand by the fixing of the head of the IGVs 13 in the external casing 15.

[0059] Optionally, in the downstream part, the tab 25 may comprise an upper part comprising the upstream face 31 substantially radial and configured to come into surface contact with the radial face, and a lower part in which a groove 33 is formed extending to the top 32 of the tab 25 (see figure 4). The bottom of the groove 33 therefore extends at a distance from the upstream face 28. The groove 33 then forms a clearance in order to prevent the tab 25 from coming into contact with the bottom 29 of the chute 26, and more precisely with the downstream connection radius between the bottom 29 and the upstream face 28 of the chute 26.

[0060] In an alternative embodiment which can be combined with the previous option, the downstream face 27 of the chute 26 can comprise an upper part comprising the inclined portion configured to come into surface contact with the downstream face and a lower part in which a groove 35 is formed extending to the bottom 29 so as to form a clearance to prevent the tab 25 from coming into contact with the bottom 29 of the chute 26, and more precisely with the downstream connection radius between the bottom 29 and the downstream face 27 of the chute 26.

[0061] If necessary, the bottom 29 of the chute 26 and the upstream face 28 can be connected by a curved surface. Optionally, the bottom 29 of the chute 26 can also be connected to the downstream face 27 by a curved surface.

[0062] The downstream internal ferrules 21, 22 of the internal casing 14 are fixed to the upstream internal ferrules 19, 20 by means of usual fixing means, typically bolted connections. The internal pivot connections 16 of the IGVs 13 are also mounted between the upstream internal ferrules 19, 20 and downstream 21, 22 of the internal casing 14.

[0063] Thus, disassembling the IGV wheel 13 into two half-shells 13a, 13b allows the external casing 15, the internal casing 14 (upstream internal shells 19, 20 and downstream 21, 22), the IGVs 13 and their pivot connections 16 to be removed simultaneously in a simple and rapid manner. Each IGV 13 of the wheel can also be replaced or repaired individually. Furthermore, removing the IGV wheel 13 allows access to be created to the rotor stage immediately downstream, typically to the booster 3, in order to allow its inspection and / or repair. In particular, the rotor stage immediately downstream remains in place in the turbomachine 1, so that it remains possible to rotate it during the inspection and to verify its proper operation.

[0064] The turbomachine 1 may further comprise a seal between the downstream internal shells 21, 22 of the internal casing 14 and the immediately downstream stage, typically a rotor stage, in order to limit the transfer of air between a first cavity 36 located between the IGV wheel 12 and the first compressor rotor in contact with the primary air stream, and a second internal cavity 37 of the turbomachine. The seal 34 may comprise a labyrinth seal, mounted on an axial flange extending downstream from the downstream internal shells 21, 22 and an associated labyrinth seal mounted on an axial flange extending upstream from a hub of the rotor stage. The rotor stage may for example comprise a stage of the booster 3.

Claims

DEMANDS 1. Assembly (12) for a turbomachine comprising: - an external casing (15) in half-shells comprising a first and a second external hemispherical ferrule (17, 18); - an inner casing (14) located radially inside the outer casing (15) and comprising a first and second internal hemispherical ferrule (19, 20); - a plurality of guide vanes (13) mounted between the outer casing (15) and the inner casing (14), - a structural housing comprising a generally cylindrical flange (23) located radially inside the internal housing (14) and exhibiting rotational symmetry with respect to an axis (X); and - a locking system (24) of the inner housing (14) on the structural housing, the locking system (24) comprising a generally annular tab (25) fixed on one of the inner housing (14) and the structural housing and a complementary channel (26) fixed on the other of the inner housing (14) and the structural housing, the channel (26) being configured to receive the tab (25) and lock it along the axis (X) relative to the structural housing.

2. Assembly (12) for a turbomachine according to claim 1, wherein the leg (25) is monolithic with the internal housing (14) and the chute (26) is monolithic with the structural housing.

3. Assembly (12) for a turbomachine according to any one of claims 1 and 2, wherein: - the chute (26) has a downstream face (27) and an upstream face (28) separated by a bottom (29), the downstream face (27) being inclined with respect to a plane normal to the axis (X); and - the leg (25) has an inclined downstream face (30) configured to come to rest against the downstream face (27) of the chute (26).

4. Assembly (12) for a turbomachine according to any one of claims 1 to 3, wherein the leg (25) has an upstream face (31) configured to bear against an upstream side (28) of the gutter, the upstream side (28) and the upstream face (31) each being parallel to a plane (P) normal to the axis (X).

5. Assembly (12) for a turbomachine according to claim 4, wherein the upstream face (31) has an external radial portion configured to bear against the pan upstream (28) of the chute (26) and an internal radial portion (33) forming an annular clearance extending at a distance from the external radial portion.

6. Assembly (12) for a turbomachine according to claim 5, wherein the chute (26) further comprises a bottom (29) connected to the upstream face (27) and / or the downstream face (28) by a curved surface.

7. Assembly (12) for a turbomachine according to any one of claims 1 to 6, wherein the inner casing (14) further comprises a first and second downstream inner ferrule (21, 22) hemispherical extending immediately downstream of the first and second inner ferrules (19, 20), a guide vane foot (13) being mounted between the first and second inner ferrules (19, 20) and the first and second downstream inner ferrules (21, 22).

8. Turbomachine (1) comprising an assembly according to claim 7.

9. Turbomachine (1) according to claim 8 further comprising a rotor mounted immediately downstream of the assembly (12), for example a booster (3).

10. Turbomachine (1) according to any one of claims 8 and 9, further comprising a turbine (6) configured to drive a blower (2) via a reduction mechanism (7), the turbine (6) being further configured to drive the rotor (3).

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