TURBOMACHINE D’AERONEF A TURBINE LIBRE

Abstract

Turbomachine (10), particularly for an aircraft, comprising: - at least one compressor (12, 14), - an annular combustion chamber (16), - at least one turbine (18), - a free turbine (20), and - an annular gas flow conduit (40) from said at least one turbine (18) to said free turbine (20), the conduit (40) being suspended from a housing (38) and connected to the housing (38) by a first mechanical linkage (L1) comprising an annular flange (50) extending radially outwards from the outer periphery of the conduit (40) and fixed to said housing (38) by fastening elements (52), and the conduit (40) being further connected to another element by a second flexible linkage (L2). Figure for the abbreviation: Fig. 2

Description

Title of the invention: FREE TURBINE AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a free turbine turbomachine, particularly for an aircraft, this turbomachine comprising a gas flow channeling device for supplying gas to the free turbine. The turbomachine may be an aircraft or helicopter engine. Technical background

[0002] An aircraft turbomachine can be traversed by one or more flows and includes at least one gas flow channeling device. Such a device defines an annular gas flow channel.

[0003] Within the framework of the present invention, a turbomachine is considered to comprise, in particular from upstream to downstream with reference to the flow of gases in the turbomachine, at least one compressor, an annular combustion chamber, at least one turbine, and also a free turbine mounted downstream of said at least one turbine.

[0004] The compressor comprises a rotor that rotates about an axis. The turbine comprises a rotor that rotates about the axis and is connected by a first shaft to the compressor rotor. Two compressors can be mounted successively one after the other and comprise rotors that are connected to each other and to the turbine rotor by the first shaft.

[0005] The compressor or compressors may be of the centrifugal type, for example. The combustion chamber may be of reverse flow and include an inlet located at a rear or downstream end of the chamber.

[0006] The free turbine also includes a movable rotor rotating around the axis and connected to a second shaft.

[0007] The first and second shafts are guided in rotation by bearings which are generally supported by annular supports fixed to a housing of the turbomachine. An annular housing extends, for example, around the combustion chamber, the turbine(s), and the free turbine. This housing can be a single piece or formed of one or more axial sections fixed end to end by clamping.

[0008] In this type of turbomachine, a ducting device is mounted between the turbine and the free turbine. The device is axially interposed between the turbine rotor and the free turbine rotor.

[0009] The device defines an annular flow channel for the gas flow exiting the turbine to feed the free turbine.

[0010] The invention relates more particularly to the mounting of this device, which ideally must meet several requirements. First, the device must be fixedly mounted to ensure optimal gas flow and supply to the free turbine. The device mounting can also be designed to allow for differential thermal expansion and relative movement with surrounding parts, vibrational stresses on surrounding parts, and to ensure a seal around the flow path defined by the device. To improve the device's lifespan and operation, it is therefore important to consider these requirements in the type of mounting and, in particular, its connection to surrounding parts.

[0011] The present invention meets this need through a simple, effective and economical solution. Summary of the invention

[0012] The invention relates to a turbomachine, in particular for an aircraft, comprising:

[0013] - at least one compressor having a rotor that rotates about an axis,

[0014] - an annular combustion chamber,

[0015] - at least one turbine comprising a movable rotor rotating about the axis and connected via a first shaft to the rotor of said at least one compressor,

[0016] - a free turbine mounted downstream of said at least one turbine and comprising a a rotating rotor that moves around the axis and is connected to a second shaft,

[0017] - a bearing support(s) for the guide bearing(s) of said first shaft and / or of said second shaft, this bearing support(s) comprising an annular portion interposed axially between the rotor of said at least one turbine and the rotor of the free turbine, and which carries or forms internal rings of the bearing(s),

[0018] - a device for channeling a flow of gas from said at least one turbine up to said free turbine, the device being axially interposed between the rotor of said at least one turbine and the rotor of the free turbine and extending at least partially around said annular part of the bearing support(s), the device defining an annular flow channel for the gas flow exiting said at least one turbine to supply said free turbine, and

[0019] - an external annular casing which surrounds at least said combustion chamber, said turbine at least one and said turbine free,

[0020] characterized in that said device is suspended from said housing which extends around the device, the device being connected to the housing by a first mechanical link which includes an annular flange extending radially outwards from the outer periphery of the device and fixed to said housing by fastening elements,

[0021] and in that the device is further connected to another element chosen from the housing and the bearing support, by a second connection which has an elastic deformation capacity in the axial and / or radial direction in operation and / or which defines at least a predetermined mounting clearance with the housing or the bearing support.

[0022] According to the invention, the device is mounted using two connections. A first mechanical connection ensures the mechanical stability of the device. According to this first connection, the device is suspended from the housing by an annular flange, which may be scalloped.

[0023] The first connection preferably allows for axial positioning and centering of the device while permitting free radial expansion relative to the housing. Axial play may exist at the flange in this connection.

[0024] A second connection provides a "flexible" connection of the device to the housing or bearing support. In the context of the present invention, a flexible connection is one capable of absorbing elastic deformations, and / or differential thermal expansions, and / or vibrations. This type of connection may, for example, include one or more assembly clearances, i.e., cold clearances that are likely to disappear when the turbomachine is in operation, elastically deformable components, etc.

[0025] The second link preferably allows the recovery of the play or each of the first link and / or the second link, to stiffen the device and to avoid the coincidence of its eigenmodes with the vibratory excitations due to imbalances, etc.

[0026] The turbomachine according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0027] — the device forms a single, non-sectorized unit;

[0028] — the device comprises two coaxial annular walls, respectively internal and external, connected together by fixed radial blades; - said flange includes an external peripheral edge interposed axially, preferably with predetermined axial clearance, between two radial support faces of said housing; - said second connection includes an annular hook at the inner periphery of the device; - said annular hook includes a cylindrical rim oriented axially towards said at least one turbine; - said cylindrical rim comprises an external cylindrical surface separated by a predetermined radial mounting clearance from an internal cylindrical surface of said bearing support, or of an element connected to said bearing support(s); - said cylindrical rim includes a free annular edge separated by a predetermined axial mounting clearance from a radial surface of said bearing support, or from an element connected to said bearing support(s); - said cylindrical rim is engaged in an annular housing of said bearing support, or of an element connected to said bearing support, this annular housing comprising said external cylindrical surface and said radial surface; - said housing is located at the external periphery of an L-shaped organ which includes a radial annular branch whose internal periphery is connected to an axial end of a cylindrical branch;

[0029] — said housing is supported by a first organ which is connected to a second organ by an elastic blade oriented radially and capable of elastic deformation;

[0030] — said first and second organs define an annular cavity with a blade radially oriented annular which connects the said first and second organs; - said second link comprises an annular row of elastically deformable blades which are distributed around the axis and located at the external periphery of the device; - the blades are fixed to the casing and each takes axial support at one or two points on said flange; - each of the blades has an elongated shape and is oriented circumferentially around the axis, each of the blades having a central part fixed to the housing and two opposite ends bearing axially on a radial face of said flange; the system of blades by their individual thrust must take up the play at the periphery of the flange in the axial direction of the aerodynamic thrust of the device. - said first and second bonds are axially separated from each other.

[0031] The invention also relates to an aircraft, such as a helicopter, comprising a turbomachine as described above. Brief description of the figures

[0032] The invention will be better understood and other details, features and advantages of the invention will become apparent from the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0033] [Fig-1] [Fig.1] is a schematic axial cross-sectional view of a turbomachine aircraft,

[0034] [Fig.2] [Fig.2] is a partial schematic axial cross-sectional view of a turbomachine according to the invention,

[0035] [Fig.3] [Fig.3] is a schematic axial cross-sectional view of an example of construction of an initial assembly connection for a turbomachine piping system,

[0036] [Fig.4] [Fig.4] is a schematic axial cross-sectional view of an example of construction of a second mounting connection for a turbomachine piping device,

[0037] [Fig. 5] [Fig. 5] is a schematic axial cross-sectional view of another example of construction of a second mounting connection for a turbomachine piping device, and

[0038] [Fig.6] [Fig.6] is a schematic axial cross-sectional view of another example of construction of a second mounting connection for a turbomachine piping device. Detailed description of the invention

[0039] Fig. 1 shows a turbomachine 10 in particular for an aircraft, which is here of the turboshaft type although this example is not limiting.

[0040] The turbomachine 10 comprises, from upstream to downstream with reference to the flow of gases in the turbomachine 10, at least one compressor 12, 14, an annular combustion chamber 16, at least one turbine 18, and a free turbine 20.

[0041] In the example shown, the turbomachine 10 comprises two compressors 12, 14 and a single turbine 18. However, it could be considered that the turbomachine 10 comprises a single two-stage compressor.

[0042] The compressors 12, 14 have rotors 12a, 14a that rotate about an axis A. The turbine 18 has a rotor 18a that rotates about the axis A and is connected by a first shaft 22 to the rotors 12a, 14a of the compressors 12, 14.

[0043] In the example shown, the compressors 12, 14 are of the centrifugal type and their rotors 12a, 14a are impellers comprising an upstream inlet oriented axially and a downstream outlet oriented radially outwards. A first rectifier-diffuser system 24 is mounted between the outlet of rotor 12a and the inlet of rotor 14a, and a second rectifier-diffuser system 26 is mounted between the outlet of rotor 14a and the inlet of the combustion chamber 16.

[0044] The combustion chamber 16 may be reverse flow and include an inlet 16a located at a rear or downstream end of the chamber, and an outlet 16b located at the internal periphery of the chamber 16.

[0045] A distributor 28 is mounted at the outlet of the chamber 16 and is therefore axially interposed between the outlet 16b and the turbine 18.

[0046] The free turbine 20 also includes a rotor 20a movable in rotation around the axis A and connected to a second shaft 30.

[0047] The shafts 22, 30 are generally tubular and the shaft 30 of the free turbine 20 extends axially inside the shaft 22 and includes an upstream or front end 30a which is for example coupled to a gearbox 32 of the mechanical reducer type for example.

[0048] The first and second shafts 22, 30 are guided in rotation by bearings 34 which are generally carried by one or more annular supports 36 fixed to a casing 38 of the turbomachine 10, as can be seen more clearly in [Fig.2].

[0049] The bearing support 36 includes an annular part 36a interposed axially between the rotor 18a of the turbine 18 and the rotor 20a of the free turbine 20, and which carries or forms internal rings of the bearings 34.

[0050] The annular housing 38 can extend around the combustion chamber 16, the turbine 18 and the free turbine 20. This housing 38 can be monobloc or formed of one or more axial sections fixed end to end by clamping.

[0051] A piping device 40 is mounted between the turbine 18 and the free turbine 20 to ensure the flow of a gas stream between them.

[0052] The device 40 is axially intercalated between the rotor 18a of the turbine 18 and the rotor 20a of the free turbine 20. The device 40 extends around the annular part 36a of the bearing support 36.

[0053] The device 40 defines an annular flow channel for the gas flow exiting the turbine 18 to feed the free turbine 20.

[0054] In the example shown, the device 40 forms a single, non-sectorized unit.

[0055] In the example shown, the device 40 comprises two coaxial annular walls, respectively internal 40a and external 40b, connected together by radial fixed blades 42. These blades 42 may be tubular and each may include an internal passage extending radially, allowing radial passage of utilities 44 through the device 40. The utilities 44 include, for example, an oil line, an electrical cable, etc.

[0056] According to the invention, the device 40 is suspended from the housing 38 which extends around the device 40.

[0057] The device 40 is connected to the housing 38 by a first mechanical link L1 which includes an annular flange 50 extending from the outer periphery of the device 40 radially outwards and fixed to the housing 38 by fastening elements 52.

[0058] The device 40 is further connected to another element chosen from the housing 38 and the bearing support 36, by a second connection L2 which has a deformation capacity elastic in axial direction in operation and / or which defines at least one mounting clearance with the housing 38 or the bearing support 36.

[0059] The first and second bonds L1, L2 are preferably axially separated from each other.

[0060] Reference is now made to the embodiments of figures 3 to 6.

[0061] In [Fig.3], it can be seen that the flange 50 comprises an external peripheral edge 50a interposed axially between two radial bearing faces 54a, 56a of the housing 38. The radial face 54a can be part of a first section 54 of the housing 38, at the level of an annular flange 54b for assembling this section 54. The radial face 56a can be part of a second section 56 of the housing 38, at the level of an annular flange 54b for assembling this section 54.

[0062] Preferably, an axial clearance JH is provided during assembly between the flange 50 and the faces 54a, 56a to allow free radial expansion of the device in operation.

[0063] The flanges 54b 56b can be applied axially against each other and fixed together by screw-nut type elements or similar, not shown.

[0064] The flange 50 can be held in place only between the faces 54a and 56a. It can also be held in place by pins 58 that are axially oriented and engaged respectively in holes in the section 54 and in radial grooves, or radial oblong holes, in the flange 50. The radial grooves or oblong holes allow the flange 50 to expand freely relative to the pins 58 and the faces 54a and 56a. Increasing the number of pins 58 (for example, 3 or more) allows the flange 50 to expand freely and enables the centering of the device 40. The holes in the section 54 open onto the face 54a. In this example, the pins 58 form the aforementioned fastening elements 52.

[0065] Figure 4 illustrates an example of an L2 connection, here at the inner periphery of device 40.

[0066] The second link L2 includes an annular hook 60 at the inner periphery of the device 40. The hook 60 is here part of the wall 40a or is connected to this wall 40a.

[0067] In the example shown, the hook 60 includes a cylindrical rim 62 oriented axially towards the turbine 18, and therefore upstream.

[0068] The cylindrical rim 62 includes an external cylindrical surface 62a separated by a predetermined radial mounting clearance JR from an internal cylindrical surface 64a of the bearing support(s) 36, or of an element connected to said bearing support(s) 36.

[0069] The cylindrical rim 62 includes a free annular edge 62b separated by a predetermined axial mounting clearance JA from a radial surface 64b of the bearing support(s) 36, or of the element connected to the bearing support(s) 36.

[0070] During operation, the clearances JR and JA are designed to disappear as much as possible. The thermal state of the components compensates for these clearances, causing a stiffening of the assembly without inducing excessive stress on the device. Furthermore, when the radial clearance is compensated, the L2 connection also provides an airtight seal in this area.

[0071] The cylindrical rim 62 is engaged in an annular housing 66 of the bearing support(s) 36, or of the element connected to the bearing support(s) 34. The external cylindrical surface 64a and the radial surface 64b are formed or located in this housing 66.

[0072] The housing 66 is preferably located on the outer periphery of an L-shaped member 68 which is part of the bearing support 36 or which is fixed or connected to this bearing support 36. The L-shaped member 68 comprises a radial annular arm 68a whose inner periphery is connected to an axial end of a cylindrical arm 68b. This particular shape confers a certain flexibility to the member and, in particular, a certain capacity for elastic deformation during operation.

[0073] To prevent the organ 68 from deforming too much and in particular from moving away from the hook 60, the radial branch 68a of the organ 68 may include at its external periphery a crenellated edge 69 able to cooperate by dog-clawing with a complementary crenellated edge 71 of the device 40, and in particular of its wall 40a.

[0074] Figure 5 illustrates an alternative embodiment of Figure 4 in which the housing 66 is supported by a first member 70 which is connected to a second member 72. Members 70 and 72 perform the same flexibility functions as reference elements 68a and 68b. A radially oriented elastic blade 74 is held captive by members 70 and 72 and closes the cavity C formed between 70 and 72.

[0075] Each of the edges 69, 71 comprises an alternation of solid parts with hollow parts. The dog-clamping consists of positioning the solid parts of the crenellated edge 69 axially opposite the hollow parts of the crenellated edge 71, moving the crenellated edge 69 axially through the crenellated edge 71, or vice versa, and then rotating the crenellated edge 69 relative to the crenellated edge 71 so that the solid parts of the crenellated edge 69 are aligned axially with the solid parts of the crenellated edge 71.

[0076] A predetermined axial play JK can be provided at the assembly between the solid parts of the crenellated edge 69 and the solid parts of the crenellated edge 71 to allow flexibility of the member 68 which is however prevented from deforming too much upstream by axial support of the solid parts of the crenellated edge 69 on the solid parts of the crenellated edge 71.

[0077] In the embodiment shown in [Fig. 4], the first member 70 has a generally cylindrical shape and includes a downstream end fixed to a downstream end of the second member 72. The upstream end of the first member 70 includes the housing 66. The blade 74 closing the cavity C includes a radially external annular edge engaged in a groove 70a of the first member 70, and a radially internal annular edge engaged in a groove 72a of the second member 72.

[0078] Fig. 6 illustrates another variant in which the second link L2 comprises an annular row of elastically deformable blades 80 which are distributed around the axis A and located at the external periphery of the device 40.

[0079] The blades 80 are preferably fixed to the housing 38 and can each bear axially at one or two points on the flange 50. The blades 80 are therefore preferably located near the flange 50.

[0080] The blades 80 have a function of “pressure” springs near the link L1 ensuring the centering and positioning of the device 40. The system of blades 80 by their individual thrust must compensate for the play JH at the periphery of the flange 50 (mentioned [Fig.3]) in the axial direction of the aerodynamic thrust of the device 40.

[0081] In the example shown, each of the blades 80 has an elongated shape and is oriented circumferentially around the axis A.

[0082] Each of the blades 80 comprises a central part 80a fixed to the housing 38 and two opposing ends 80b, 80c bearing axially on a radial face of the flange 50. The blades 80 are here located axially upstream of the flange 50 and therefore bearing on an upstream radial face of the flange 50.

[0083] The blades 80 can be attached to the housing 38 by means of screw-nut or similar fastening elements 82. In this example, the same fastening elements 52 (consisting of 58 and radial grooves cut into the flange 50) are used to attach and center the device 40 to the housing 38 according to the first connection LL

[0084] The double bond L1 and L2 according to the invention offers numerous advantages, for example: - to push the potential vibrational responses of the device outside of its operating ranges, - to maintain a thermomechanical and vibratory stress compatible with the mechanical resistance of the device, - the creation of a seal at one end of the device, - limiting the flow of calories from the device to the bearing support, - increase the reliability of bearings bearing 34, by limiting the risk of coking.

Claims

1. Demands Turbomachine (10), in particular for an aircraft, comprising: - at least one compressor (12, 14) having a rotor (12a, 14a) movable in rotation about an axis (A), - an annular combustion chamber (16), - at least one turbine (18) comprising a rotor (18a) movable in rotation around the axis (A) and connected by a first shaft (22) to the rotor (12a, 14a) of said at least one compressor (12, 14), - a free turbine (20) mounted downstream of said at least one turbine (18) and comprising a rotor (20a) movable in rotation around the axis (A) and connected to a second shaft (30), - a support (36) for bearing(s) with guide bearing(s) of said first shaft (22) and / or said second shaft (30), this bearing support (36) comprising an annular portion (36a) axially interposed between the rotor (18a) of said at least one turbine (18) and the rotor (20a) of the free turbine (20), and which carries or forms internal rings of the bearing(s) (34), - a device (40) for channeling a gas flow from said at least one turbine (18) to said free turbine (20), the device (40) being axially interposed between the rotor (18a) of said at least one turbine (18) and the rotor (20a) of the free turbine (20) and extending at least partially around said annular portion (36a) of the bearing support(s) (36), the device (40) defining an annular flow channel for the gas flow exiting said at least one turbine (18) to feed said free turbine (20), and - an external annular casing (38) which surrounds at least said combustion chamber (16), said at least one turbine (18) and said free turbine (20), characterized in that said device (40) is suspended from said housing (38) which extends around the device (40), the device (40) being connected to the housing (38) by a first mechanical link (L1) which includes an annular flange (50) extending from the outer periphery of the device (40) radially outwards and fixed to said housing (38) by fastening elements (52), and in that the device (40) is further connected to another element chosen from the housing (38) and the bearing support(s) (36), by a second connection (L2) which has an elastic deformation capacity in axial and / or radial direction in operation and / or which defines at least one predetermined mounting clearance (JR, JA) with the housing (38) or the bearing support(s) (36).

2. Turbomachine (10) according to claim 1, wherein said flange (50) comprises an external peripheral edge (50a) axially interposed, preferably with predetermined axial clearance (JH), between two radial support faces (54a, 56a) of said housing (38).

3. Turbomachine (10) according to claim 1 or 2, wherein said second linkage (L2) comprises an annular hook (60) at the inner periphery of the device (40).

4. Turbomachine (10) according to claim 3, wherein said annular hook (60) comprises a cylindrical rim (62) oriented axially towards said at least one turbine (18).

5. Turbomachine (10) according to claim 4, wherein said cylindrical rim (62) comprises an external cylindrical surface (62a) separated by a predetermined radial mounting clearance (JR) from an internal cylindrical surface (64a) of said bearing support(s) (36), or of an element connected to said bearing support(s) (36).

6. Turbomachine (10) according to claim 5, wherein said cylindrical rim (62) comprises a free annular edge (62b) separated by a predetermined axial mounting clearance (JA) from a radial surface (64b) of said bearing support(s) (36), or from an element connected to said bearing support(s) (36).

7. Turbomachine (10) according to claim 6, wherein said cylindrical rim (62) is engaged in an annular housing (66) of said bearing support(s) (36), or of an element connected to said bearing support(s) (36), this annular housing (66) comprising said external cylindrical surface (64a) and said radial surface (64b).

8. Turbomachine (10) according to claim 7, wherein said housing (66) is located at the outer periphery of an L-shaped member (68) which includes a radial annular arm (68a) whose inner periphery is connected to an axial end of a cylindrical arm (68b).

9. Turbomachine (10) according to claim 1 or 2, wherein said second link (L2) comprises an annular row of elastically deformable blades (80) which are distributed around the axis (A) and located at the external periphery of the device (40).

10. Turbomachine (10) according to claim 9, wherein the blades (82) are fixed to the casing (38) and each bear axially at one or two points on said flange (50).

11. Turbomachine (10) according to claim 9 or 10, wherein each of the blades (80) has an elongated shape and is oriented circumferentially around the axis (A), each of the blades (80) comprising a central part (80a) fixed to the housing (38) and two opposite ends (80b, 80c) bearing axially on a radial face of said flange (50).

12. Turbomachine (10) according to any one of the preceding claims, wherein said first and second links (L1, L2) are axially separated from each other.

13. Aircraft, such as a helicopter, comprising a turbomachine (10) according to any one of the preceding claims.

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