Fastening of exhaust cone in turbine nozzle

Abstract

The invention relates to an assembly for a turbine of a turbomachine having a longitudinal axis (X), comprising: - an exhaust cone (100) comprising an outer annular wall (102) for the flow of a main air flow and an annular box arranged radially inside the outer annular wall (102), the annular box comprising an inner annular wall (104) arranged radially inside the outer annular wall of the exhaust cone, - an exhaust casing arranged upstream of the exhaust cone, and - a connecting part (106) flexible in radial direction, longitudinally inserted between the exhaust casing and the exhaust cone (100), the connecting part being fastened to the exhaust casing and to the inner annular wall (104), and wherein the inner annular wall (104) is connected to the outer annular wall (102) by a fastening member (112) configured so that the inner annular wall (104) moves in circumferential and longitudinal directions relative to the outer annular wall (102).

Description

Technical Field

[0001] The present invention relates to a component for securing an exhaust cone in a turbine nozzle, and more particularly, to a component for securing an exhaust cone made of a ceramic matrix composite material. Background Technology

[0002] This disclosure relates to an assembly located at the rear (downstream) end of an aircraft turbojet engine for optimizing the hot gas flow exhausted by the turbojet engine and potentially absorbing at least a portion of the noise generated by the interaction of these hot gases from internal engine components (combustion chamber, turbine) with ambient air and with the cold air flow exhausted by the turbojet engine's fan.

[0003] More specifically, this disclosure relates to the connection between an object often referred to as an exhaust cone and a gas outlet from a turbojet engine located just upstream.

[0004] Typically, the exhaust cone is surrounded (encircled) by what is known as the main nozzle section.

[0005] The exhaust cone is designed to be positioned downstream of the turbine section of the turbojet engine, with the main nozzle placed concentrically around it. Both the exhaust cone and the main nozzle are fastened to the turbojet engine housing by a system for flange fastening.

[0006] Known Figure 1 The assembly of the aircraft turbojet engine, as shown in the figure, includes: - A central exhaust element, which is annular around the longitudinal axis X and configured to allow gas to be ejected from the surrounding turbojet engine from upstream to downstream, and - A connecting flange, which is inserted between the so-called metal outlet of the upstream turbojet engine and the downstream center element to connect them together.

[0007] The aforementioned longitudinal axis X is the longitudinal axis or rotation axis of the moving blades of the turbine, specifically the fan 20 and the engine 12.

[0008] The central exhaust element may correspond to the aforementioned exhaust cone (hereinafter referred to as 1), or at least to the upstream portion 1a as described below.

[0009] Figure 1 The diagram shows a conventional exhaust cone 1, with the upstream (AM) and downstream (AV) structures along the engine axis (the longitudinal axis X mentioned above) located on it from the left and right respectively.

[0010] More generally, Figure 1The image shows an aircraft gas turbine engine 10, forming a gas turbine engine 12, the central portion of which is mounted inside an engine nacelle assembly 14, as is typical of aircraft designed for infrasonic operation, such as turboprop or turbofan engines. Generally, the nacelle assembly 14 includes an engine nacelle 16 and a fan shroud 18 surrounding a fan 20 axially located upstream of the engine 12.

[0011] The engine 12 includes at least one turbine, which may be a low-pressure turbine, located axially in the downstream portion, and an exhaust casing 22, still in the downstream portion, the exhaust casing including an inner annular shroud 22a and an outer annular shroud 22b, which delineate the downstream portion of a main circulation path 24 in which combustion gases from the combustion chamber of the engine 12 flow.

[0012] An inner annular shield 22a is connected to an exhaust cone 1 at its downstream end, the exhaust cone including an upstream portion 1a having a generally cylindrical shape and a downstream portion 1b having a conical shape.

[0013] In practice, connecting the aforementioned metal outlet of a turbojet engine (which may be the internal annular shroud 22a) to the central element (which may be the upstream portion 1a of the exhaust cone 1) remains challenging. In reality, at least one portion of the exhaust cone is made of a different material than the exhaust casing, which induces thermomechanical stress, creating a thermal gradient between the portion of the exhaust cone and the exhaust casing. Additionally, a sound box may be arranged inside the exhaust cone to reduce exhaust noise pollution. The connection between the sound box and the exhaust casing and / or the exhaust cone is also complex because the different materials result in different thermomechanical stresses. Summary of the Invention

[0014] This disclosure proposes the use of an assembly of an exhaust cone and an exhaust casing, which is more reliable and robust in terms of thermal gradient due to the fact that it connects any of the aforementioned parts.

[0015] For this purpose, this disclosure provides an assembly of nozzles for a turbine having a longitudinal axis, more specifically for a turbine, comprising: - An exhaust cone comprising an outer annular wall for the flow of a main airflow and an annular box radially disposed within the outer annular wall, which may be an annular box comprising an inner annular wall radially disposed within the outer annular wall of the exhaust cone. -Exhaust casing, which is arranged upstream of the exhaust cone, and A connecting component, which is flexible in the radial direction, is longitudinally inserted between the exhaust casing and the exhaust cone. The connecting component is fastened to the exhaust casing and the inner annular wall. The inner annular wall is connected to the outer annular wall by a fastening member configured such that the inner annular wall can move relative to the outer annular wall in the circumferential and longitudinal directions.

[0016] Therefore, the fastening member allows for circumferential and axial degrees of freedom for both the inner and outer annular walls, which reduces the thermomechanical stresses exerted on the inner and outer annular walls due to material differences. Furthermore, the fastening member allows the outer annular wall to remain attached to the inner annular wall, thus reducing the cantilever of the outer annular wall and consequently its mass.

[0017] In this disclosure, upstream and downstream are defined relative to the air inlet and outlet of the turbine, with upstream corresponding to the air inlet and downstream corresponding to the air outlet. Furthermore, the axial direction corresponds to the direction of the turbine's rotating shaft (which corresponds to the axis of rotation of the rotating portion of the turbine), and the radial direction is perpendicular to the rotating shaft.

[0018] The fastening member can be installed to have a first gap in the circumferential direction and a second gap in the longitudinal direction with the inner annular wall.

[0019] The fastening member can be installed to have a first gap in the circumferential direction and a second gap in the longitudinal direction with the outer annular wall.

[0020] The first gap may be equal to or different from the second gap.

[0021] At least one of the fastening components may include a screw and a nut. The assembly may include an annular gap between the orifice of the inner annular wall and the orifice of the outer annular wall. Each fastening component may be as previously mentioned.

[0022] The annular gap may have a circular or elongated elliptical shape.

[0023] At least one of the fastening components may include a clamping ring and a flexible cup-shaped washer, the flexible cup-shaped washer being pre-stressed between the clamping ring and the inner annular wall.

[0024] Cup-shaped washers can be sized to hold the inner annular wall against the outer annular wall in place, while taking into account geometric tolerances, thermal expansion, and flight movement.

[0025] In some flight conditions, the cup-shaped gasket can deform radially to absorb radial deformation of the inner annular wall caused by thermomechanical stress.

[0026] The annular gap can be sized according to the thermal expansion of the surrounding portion, such as a clamping ring or a cup-shaped washer.

[0027] Each fastening member's clamping ring can be installed with an annular gap in an opening in the inner or outer annular wall. For example, the annular gap can be provided between the radially outer surface of the clamping ring and the radially inner surface of the opening in the inner or outer annular wall.

[0028] Each fastening component may further include at least one wear-resistant washer. The assembly may include a first wear-resistant washer radially arranged between the inner annular wall and the outer annular wall, and a second wear-resistant washer radially arranged between the inner annular wall and the cup-shaped washer. This reduces wear caused by friction between the inner and outer annular walls.

[0029] The connecting component may include an annular flange and a plurality of fastening lugs circumferentially distributed around a longitudinal axis, the annular flange being connected to the exhaust casing and the fastening lugs being connected to an inner annular wall. At least one of the fastening components may be arranged opposite to the circumferential space between two consecutive fastening lugs.

[0030] This arrangement allows for the restriction of the radial volume of the fastening components.

[0031] The fastening lugs of the connecting components can be rigid or flexible. Flexible fastening lugs allow for compensation of thermal expansion between the exhaust cone and the exhaust casing.

[0032] The inner annular wall may include an upstream portion that is radially inserted between the inner annular wall and the connecting member, the upstream portion of the inner annular wall being connected to the outer annular wall by a fastening member.

[0033] Each fastening lug can be connected to the inner annular wall via a connecting member, and each of the fastening members and connecting members forms an annular row.

[0034] An annular fairing, which can be formed by several corner sections, can be connected to the upstream portion of the outer annular wall. The fairing can surround the connecting component and form continuity with the exhaust casing's shroud to define the inner annular surface defining the flow path of the main airflow. The fairing can be connected to the upstream portion of the annular flange.

[0035] Multiple support members are circumferentially distributed around the longitudinal axis and connected to the inner annular wall, with the fairing fixed against the support members.

[0036] The annular seal can be longitudinally arranged between the outer annular wall and the exhaust casing, and configured to limit leakage of the main airflow toward the interior of the inner annular wall.

[0037] The annular enclosure can be an acoustic annular enclosure. An acoustic annular enclosure allows for the limitation of noise pollution caused by the flow of gas from the turbine. The annular enclosure may include multiple acoustic zones extending radially outward from the inner annular wall of the enclosure. These acoustic zones may be metallic.

[0038] The inner or outer annular wall can be made of composite materials or metallic materials.

[0039] The exhaust cone may include, for example, a conical downstream portion connected to an outer annular wall made of a ceramic matrix composite.

[0040] The exhaust casing can be made of metal.

[0041] This disclosure also provides a nozzle comprising the assembly as previously mentioned, and a turbine comprising the nozzle. Attached Figure Description

[0042] [ Figure 1 ] Figure 1 The above is a schematic cross-sectional view of a turbine used in an aircraft.

[0043] [ Figure 2 ] Figure 2 This is a perspective view of the upstream portion of the assembly according to the first embodiment.

[0044] [ Figure 3 ] Figure 3 a and 3b represent partial views of the assembly according to the first embodiment.

[0045] [ Figure 4 ] Figure 4 a and 4b indicate equipment Figure 2 and 3 A cross-sectional view of the fastening components of the assembly.

[0046] [ Figure 5 ] Figure 5 Indicates equipment Figure 2 and 3 A cross-sectional view of the fastening components of the assembly.

[0047] [ Figure 6 ] Figure 6 express Figure 2 and 3 A partial view of a variant of the assembly.

[0048] [ Figure 7 ] Figure 7 a and 7b represent partial views of the assembly according to the second embodiment. Detailed Implementation

[0049] Figure 2 , 34 and 4 denote a portion of a turbine assembly according to a first embodiment of the present invention. This assembly includes an exhaust cone 100, which, on its upstream side, includes an outer annular wall 102 defining a flow path for a hot gas flow and an annular box radially disposed within the outer annular wall 102. The annular box includes an inner annular wall 104 radially disposed within the outer annular wall 102 and a plurality of acoustic zones disposed between the outer annular wall 102 and the inner annular wall 104. The inner and outer annular walls are annular about a longitudinal axis X. A detailed description is given with reference to an acoustic annular box. However, this disclosure is applicable to other types of annular boxes, which are not necessarily acoustic.

[0050] The assembly further includes an exhaust casing (not shown). An inner annular wall 104 of the exhaust cone 100 is connected to the exhaust casing by a connecting flange 106. An outer annular wall 102 forms a surface continuity with a portion of the exhaust casing to define the flow path of the main airflow.

[0051] The connecting flange 106 includes an annular flange 108 forming an upstream annular portion and a fastening lug 110 extending axially downstream from the annular flange 108. The fastening lugs 110 are evenly distributed on the circumference and spaced apart from each other circumferentially. The annular flange 108 is connected to the exhaust casing by bolted fastening members 107, and the fastening lugs 110 are fastened to the inner annular wall 104 of the exhaust cone 100. The fastening lugs 110 can be flexible or rigid. The connecting flange 106 can be metal.

[0052] The downstream portion of the outer annular wall 102 is also connected to the downstream portion of the inner annular wall 104.

[0053] The upstream portion of the outer annular wall 102 is also connected to the upstream portion 114 of the inner annular wall 104 via a fastening member 112. The upstream portion 114 of the inner annular wall 104 is formed by an annular wall extending radially outward to engage the outer annular wall 102. The upstream portion 114 may be an annular wall that is attached to and fastened to the inner annular wall 104 by screwing, in particular by directly screwing, onto the fastening lug 110. The upstream portion 114 may be integrally formed with the inner annular wall 104.

[0054] The exhaust cone 100 includes a conical downstream portion made of a composite material having a ceramic matrix.

[0055] The outer annular wall 102 and the inner annular wall 104 may be made of a composite material or a metallic material with a ceramic matrix.

[0056] During operation, the assembly is subjected to high temperatures, which induces considerable thermomechanical stress at both the outer and inner annular walls. To mitigate the effects of thermomechanical stress, the fastening member 112 is mounted with an annular gap 118 in the upstream portion 114 of the inner annular wall 104.

[0057] The fastening member 112 includes a plurality of screws 116 evenly distributed around the circumference and spaced apart from each other along the circumference. The screws 116 are mounted to have annular gaps 118 in corresponding orifices in the upstream portion 114 of the inner annular wall 104. The screws 116 extend radially inward.

[0058] The annular gap 118 allows for circumferential and axial movement of the inner annular wall 104 relative to the outer annular wall 102. Therefore, this arrangement allows for thermal expansion of the inner annular wall in both the circumferential and axial directions.

[0059] The fastening member 112 can be installed to have an annular gap 118 in the corresponding mounting hole of the outer annular wall 102.

[0060] Each screw 116 may be arranged opposite to the annular flange 108 of the fastening lug 110 or the connecting flange 106. Thus, each screw may form a radial stop for the outer annular wall and the inner annular wall, thereby limiting the radial deflection of the annular wall due to thermomechanical stress.

[0061] Each screw 116 can be arranged opposite the circumferential space between two consecutive fastening lugs 110. This arrangement allows for a reduction in the radial volume of the assembly.

[0062] Each fastening member 112 further includes a nut 120 and a clamping ring 122, the clamping ring being radially inserted between the nut 120 and the outer annular wall 102. The clamping ring 122 is mounted to have an annular gap 118 relative to the upstream portion 114 of the inner annular wall 104.

[0063] Each fastening member 112 further includes a cup-shaped washer 124, which is formed by an annular portion and a plurality of tabs spaced circumferentially around the annular portion of the cup-shaped washer 124. The tabs can deform in the radial direction when subjected to stresses above a tolerance threshold to reduce the structural integrity of the assembly in the event of operational damage, such as loss of turbine blades.

[0064] The annular gap 118 can be sized according to the thermal expansion of the surrounding parts of, for example, the nut 120, the clamping ring 122, the screw 116, etc.

[0065] Each screw 116 has a conical head 115 disposed within a housing 126, which is located in the radially outer surface of the outer annular wall 102. Therefore, the fastening member 112 does not affect the flow of the main airflow, and thus does not affect the aerodynamic profile of the outer annular wall 102.

[0066] Each fastening member 112 further includes a countersunk ring 128 having a shape complementary to the shape of the conical head 115 and receiving the conical head 115 of the screw 116. The countersunk ring 128 allows for limiting friction between the screw 116 and the outer annular wall 102. This also allows for a reduction in the risk of breakage of the outer annular wall 102 when tightening the screw. In fact, if the countersunk hole of the screw were directly clamped onto the outer annular wall 102, this would induce too much force in the outer annular wall 102. The metal ring 128 allows for clamping the joints in pairs, and the ring 128 rests on a plane on the outer annular wall 102.

[0067] exist Figure 4 In the variant indicated in b, each fastening member 112 includes a first wear-resistant washer 130 disposed between the cup-shaped washer 124 and the inner annular wall 104.

[0068] Each fastening member 112 includes a second wear-resistant washer 132 disposed between the outer annular wall 102 and the inner annular wall 104.

[0069] The first wear-resistant washer 130 and the second wear-resistant washer 132 allow for the restriction of wear on portions of the fastening member 112 as well as the inner and outer annular walls.

[0070] The annular gap 118 can be circular or elongated elliptical.

[0071] exist Figure 5 In a variant, each screw 116 has a protruding head 215 that projects radially outward from the housing 126. The protruding head 215 may also not be surrounded by the ring 128. The head 215 may also be formed to project radially outward completely from the outer annular wall 102, and the annular gap 127 may be absent, the head being radially applied toward the interior of the outer annular wall 102.

[0072] exist Figure 6 In a variant, the assembly includes an annular seal 200 radially disposed between the connecting flange 106 and the outer annular wall 102 to seal the radial annular space between the connecting flange 106 and the outer annular wall 102. The seal 200 includes a cylindrical portion disposed around the connecting flange 106 and an annular wall extending toward the outer annular wall 102. The seal 200 further includes an annular edge extending axially and disposed to contact the inner surface of the outer annular wall 102.

[0073] The seal 200 may be formed from multiple corner sections connected together or integrally formed, for example in the form of a slit-type annular seal.

[0074] Figure 7 This represents a portion of a turbine assembly according to a second embodiment of the present invention. This assembly is related to… Figure 6 The assemblies contain the same components. Unlike... Figure 6 The assembly includes an outer annular wall 102 having an upstream portion 302 extending radially toward an inner annular wall 104. The upstream portion 302 of the outer annular wall 102 is connected to the inner annular wall 102 by a fastening member 112.

[0075] The fastening member 112 is installed to have an annular gap 118 in the corresponding opening of the outer annular wall 102.

[0076] The upstream portion 302 of the annular wall 102 includes a plurality of recesses 304 that extend radially and are spaced apart circumferentially. A component 107 for fastening the inner annular wall 104 to the connecting flange 106 is formed in the recesses 304.

[0077] Each of the fastening members 112 and fastening components 107 is arranged in an annular row around the inner annular wall 104. The annular rows of fastening members 112 and fastening components 107 may be axially offset from each other. They may also be arranged in the same axial position. In either case, the fastening members 112 and fastening components 107 are arranged alternately along the circumference.

[0078] The assembly further includes a plurality of supports 306 circumferentially distributed around an inner annular wall 104. Lugs are fastened to the inner annular wall 104, particularly to a connecting flange 106. The supports 306 extend radially outward from the annular wall 104.

[0079] The assembly further includes an annular fairing 308, which is arranged around the connecting flange 106 and forms a continuity of part of the exhaust casing to define the flow path of the main airflow.

[0080] The annular fairing 308 is connected to the upstream portion of the outer annular wall 102. The annular fairing 308 is fastened to the annular flange 108 by means of a bracket. An annular seal can be radially inserted between the annular fairing 308 and the annular flange 108.

[0081] In different embodiments, an annular gap 127 exists between the ring and the periphery of the outer annular wall 102's outer shell 126, allowing for thermal expansion of the ring 128 and axial movement of the outer annular wall 102. For reasons relevant to the illustrations in the figures, this annular gap 127 is only present in... Figure 4 and 5 As shown in the image.

Claims

1. An assembly of nozzles for a turbine having a longitudinal axis (X), comprising: - An exhaust cone (100) includes an outer annular wall (102) for the flow of the main airflow and an annular box arranged radially inside the outer annular wall (102), the annular box including an inner annular wall (104) arranged radially inside the outer annular wall of the exhaust cone. -Exhaust casing, which is arranged upstream of the exhaust cone, and - A connecting component (106), which is flexible in the radial direction, is longitudinally inserted between the exhaust casing and the exhaust cone (100), the connecting component being fastened to the exhaust casing and the inner annular wall (104), and The inner annular wall (104) is connected to the outer annular wall (102) by a fastening member (112) configured such that the inner annular wall (104) moves relative to the outer annular wall (102) in the circumferential and longitudinal directions.

2. The assembly according to claim 1, characterized in that, The fastening member (112) is installed such that it has a first gap with the inner annular wall and the outer annular wall in the circumferential direction and a second gap in the longitudinal direction.

3. The assembly according to claim 1 or 2, characterized in that, At least one of the fastening members (112) includes a screw and a nut, the assembly includes an annular gap (118) between the orifice of the inner annular wall (104) and the screw, and the assembly includes an annular gap (127) between the orifice of the outer annular wall (102) and the screw.

4. The assembly according to claim 3, characterized in that, At least one of the fastening members (112) includes a clamping ring (122) and a flexible cup-shaped washer (124) that is radially prestressed between the clamping ring (122) and the inner annular wall (104).

5. The assembly according to claim 4, characterized in that, The clamping ring (122) is installed to have an annular gap (118) in the orifice of the inner annular wall (104).

6. The assembly according to claim 1, characterized in that, Each fastening member (112) further includes at least one wear-resistant washer (130, 132).

7. The assembly according to claim 1, characterized in that, The connecting component (106) includes an annular flange (108) and a plurality of fastening lugs (110) circumferentially distributed around the longitudinal axis (X), the annular flange (108) being connected to the exhaust casing and the fastening lugs being connected to the inner annular wall, and at least one of the fastening members (112) being arranged opposite to the circumferential space between two consecutive fastening lugs.

8. The assembly according to claim 7, characterized in that, Each fastening lug (110) is connected to the inner annular wall (104) via a connecting member (107), and each of the fastening members (112) and the connecting members (107) forms an annular row.

9. The assembly according to claim 1, comprising a fairing (308) connected to the outer annular wall (102), surrounding the connecting member (106) and forming a continuous shroud of the exhaust casing to define an inner annular surface defining the flow path of the main airflow.

10. The assembly according to claim 9, comprising a plurality of supports (306) circumferentially distributed around the longitudinal axis (X) and connected to the inner annular wall (104), the fairing (308) being fixed against the supports (306).

11. The assembly according to claim 1, comprising an annular seal (200) longitudinally disposed between the outer annular wall (102) and the exhaust casing, and configured to restrict leakage of the main airflow toward the interior of the inner annular wall (104).

12. A nozzle comprising the assembly according to any one of claims 1 to 11.

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