Fastening of exhaust cone in turbine nozzle
By introducing elastic components and annular seals into the assembly of the exhaust cone and exhaust casing, the thermomechanical stress and noise problems in the connection between the exhaust cone and exhaust casing are solved, resulting in a more stable connection and noise reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SAFRAN NASEL
- Filing Date
- 2021-11-03
- Publication Date
- 2026-06-02
AI Technical Summary
In the prior art, the connection between the exhaust cone and the exhaust casing is difficult to cope with the thermomechanical stress caused by the thermal gradient, and the noise reduction effect is not good.
The design employs an assembly consisting of an outer annular wall, an inner annular wall, and connecting components. An elastic member and a radial displacement limiting member are provided between the outer and inner annular walls. The elastic member adapts to thermal expansion and reduces vibration, while an annular seal is provided between the inner and outer annular walls to reduce air backflow.
It improves the connection stability between the exhaust cone and the exhaust casing, reduces thermomechanical stress, lowers noise pollution, and optimizes airflow performance.
Smart Images
Figure CN116507798B_ABST
Abstract
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 composite having a ceramic matrix. 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. The exhaust cone is 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.
[0005] Known Figure 1 The assembly of the aircraft turbojet engine, as shown in the figure, includes:
[0006] - A central exhaust element, which is annular around the longitudinal axis X and adjusted to allow gas to be ejected from the surrounding turbojet engine from upstream to downstream, and
[0007] - 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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 define the downstream portion of a main annular flow path 24 in which combustion gases from the combustion chamber of the engine 12 flow.
[0013] An inner annular shroud 22a is connected to an exhaust cone 1 at its downstream end. The exhaust cone may include: an upstream portion 1a, which has a generally cylindrical shape on conventional engines and a bifurcated and converging conical shape on other engines; and a downstream portion 1b, which has a conical shape.
[0014] 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 material different from the exhaust casing, causing differential expansion of the current components and the generation of thermomechanical stresses due to the thermal gradient between the portion of the exhaust cone and the exhaust casing. Furthermore, a sound box may be arranged inside the exhaust cone to reduce exhaust noise pollution. The connection from the sound box to the exhaust casing and / or to the exhaust cone is also complex due to the differences in material expansion and the temperature difference between the flow path and the internal portions of the sound region (which generates thermomechanical stresses). Summary of the Invention
[0015] This disclosure proposes the use of an exhaust cone to an exhaust casing assembly, which is more reliable and robust for thermal gradients due to its connection to any of the aforementioned parts.
[0016] Therefore, this disclosure provides an assembly of nozzles for a turbine having a longitudinal axis, and more particularly for said turbine, comprising:
[0017] - An exhaust cone comprising an outer annular wall for the flow of a main airflow and an annular box, which may be an annular acoustic chamber, radially arranged inside the outer annular wall, the annular box comprising an inner annular wall radially arranged inside the outer annular wall of the exhaust cone.
[0018] - The exhaust casing, which is located upstream of the exhaust cone, and
[0019] A connecting component, which is longitudinally inserted between the exhaust casing and the exhaust cone, is fastened to the exhaust casing and the inner annular wall.
[0020] The assembly further includes at least one elastic member that is radially deformable and radially prestressed between the outer annular wall and the connecting component.
[0021] Specifically, the downstream portion of the inner annular wall can be fastened to the downstream portion of the outer annular wall.
[0022] According to this paper, the upstream portion of the outer annular wall is free to move relative to the upstream portion of the inner annular wall.
[0023] Therefore, the radial movement of the outer annular wall is restricted, while it moves freely relative to the upstream portion of the inner annular wall in the axial and circumferential directions. This arrangement allows for force distribution between the upstream and downstream interfaces of the outer annular wall, thus reducing the thickness and mass of the outer annular wall. Furthermore, the elastic member prevents the outer annular wall from vibrating in the engine's excitation mode and limits the force at the downstream interface of the outer annular wall. Additionally, the elastic member is capable of accommodating geometric tolerances and the thermal expansion of components made of different materials, such as connecting parts or the outer annular wall itself.
[0024] The elastic member can be prestressed radially by the outer annular wall abutting against the inner annular wall, rather than by the connecting parts.
[0025] In this disclosure, upstream and downstream are defined relative to the air inlet and outlet of the nozzle, with upstream corresponding to the air inlet and downstream corresponding to the air outlet. Furthermore, the axial direction corresponds to the direction of the rotation axis of the nozzle of the exhaust cone (which corresponds to the rotation axis of the turbine), and the radial direction is perpendicular to said rotation axis.
[0026] The upstream portion of the outer annular wall may not contain any mechanical connection to the inner annular wall or any other portion of the exhaust cone. According to one embodiment, the assembly may include a member for limiting radial displacement of the outer annular wall. The radial displacement limiting member may be inserted radially between the outer annular wall and the connecting member, and abuts against the connecting member to form a radial stop for the outer annular wall.
[0027] The components used to limit the radial displacement of the outer annular wall allow for support of the outer annular wall in the downstream region and avoid large cantileveres of the outer annular wall between the downstream region and the downstream area.
[0028] The radial displacement limiting member can be in continuous or point contact with the connecting component.
[0029] The elastic member can be fastened to the outer annular wall and can make radial contact with the connecting parts.
[0030] The elastic member can be fastened to the connecting part and can make radial contact with the outer annular wall.
[0031] According to one embodiment, at least one elastic member, specifically each elastic member, may be superimposed on a radial displacement limiting member. Each elastic member may be fastened to the displacement limiting member. Thus, each elastic member may be circumferentially arranged at the same location on the radial displacement limiting member.
[0032] According to one embodiment, at least one elastic member, specifically each elastic member, may be circumferentially spaced from one of the radial displacement limiting members.
[0033] At least one elastic member, specifically each elastic member, may be a leaf spring, which is circumferentially distributed around the longitudinal axis.
[0034] Leaf springs allow the transmission of forces from the external annular wall depending on the flight conditions (ultimate, limit, or some fatigue conditions).
[0035] At least one leaf spring, specifically each leaf spring, may include a first flexible blade extending in a first direction in a circumferential direction about a longitudinal axis, and a second flexible blade extending in a second direction in a circumferential direction about the longitudinal axis opposite to the first direction.
[0036] The first and second blades can extend radially inward from the outer annular wall.
[0037] At least one leaf spring, specifically each leaf spring, may include a single leaf extending radially and along a longitudinal axis.
[0038] At least one leaf spring, specifically each leaf spring, may extend radially inward or outward.
[0039] At least one leaf spring, specifically each leaf spring, may form a radial displacement limiting member.
[0040] Radial displacement limiting components can be integrated into or attached to leaf springs.
[0041] The assembly may include a first annular seal surrounding the interface between the connecting component and the inner annular wall. The first annular seal may be configured to restrict the circulation of the main airflow toward the cavity of the exhaust cone.
[0042] The first annular seal can be arranged to axially cover the space between the exhaust casing and the inner annular wall.
[0043] The first annular seal may be metal and belong to the "finger seal" type. The first annular seal may include multiple corner sections circumferentially distributed around the longitudinal axis and connected together to form the first annular seal.
[0044] The first annular seal may be made of tungsten or a chromium-nickel-iron alloy.
[0045] The assembly may include a second annular seal that is connected to the connecting component and extends radially toward the outer annular wall. The second annular seal may be configured to prevent the main airflow from passing through the outer annular wall.
[0046] The second annular seal allows for reduced recirculation of the main airflow and thus reduces the impact on the performance of the nozzles, including the assembly.
[0047] The second annular seal can be arranged to axially cover the space between the exhaust casing and the outer annular wall.
[0048] The second annular seal can be connected to the connecting component and contact the outer annular wall.
[0049] The second annular seal may be metal and may include multiple corner sections circumferentially distributed around the longitudinal axis and connected together to form the second annular seal.
[0050] According to one embodiment, the elastic member may be formed of an annular seal, which is fastened to the connecting member and includes a radially deformable portion pressing against an outer annular wall.
[0051] The annular seal can be angled and continuous, and can be integrally formed, or can be formed by multiple angular sections superimposed at its ends.
[0052] The annular seal can be fastened to the connecting component at the first end.
[0053] An annular seal may include a second end that presses against the inner annular wall.
[0054] The annular seal may include a second end arranged radially outward relative to the first end.
[0055] The annular seal may include a radially outwardly extending bulge located axially between the first and second ends and capable of connecting to an external annular wall.
[0056] The annular seal can be made of metal.
[0057] Each displacement limiting member may be formed of a buffer, which is circumferentially distributed around the longitudinal axis and can maintain a predetermined distance from the connecting member in the radial direction, especially when the outer annular wall is stationary.
[0058] The predetermined distance may depend on geometric tolerances, thermal expansion of the parts, and some flight conditions, which may be a combination of daily or occasional loads and loads.
[0059] The downstream portion of the inner annular wall can be fastened to the downstream portion of the outer annular wall.
[0060] The connecting components may include an annular flange connected to a corresponding flange of the exhaust casing, and a plurality of fastening lugs circumferentially distributed around the longitudinal axis and connected to the inner annular wall.
[0061] The fastening lug can be rigid, thus forming a fastening flange on the connecting parts. Alternatively, the fastening lug can be flexible, thus forming a flexible connecting flange on the connecting parts. Flexible fastening lugs allow for the absorption of thermal expansion between the exhaust cone and the exhaust casing.
[0062] In the case where the annular enclosure is a ring-shaped acoustic enclosure designed to absorb and reduce air outlet noise, the ring-shaped acoustic enclosure may include multiple sound zones extending radially outward from the inner annular wall of the ring-shaped acoustic enclosure. The sound zones may be metallic.
[0063] The inner or outer annular wall can be made of composite or metallic materials.
[0064] The exhaust cone may include a downstream portion made of a composite material having a ceramic matrix and connected to an outer annular wall.
[0065] The exhaust casing can be made of metal.
[0066] This disclosure also provides a nozzle for a turbine that includes the assembly mentioned above. Attached Figure Description
[0067] [ Figure 1 [: already described] Figure 1 This shows a schematic cross-sectional configuration of a turbine used in an aircraft.
[0068] [ Figure 2 ]: Figure 2 A schematic cross-sectional view showing a portion of an exhaust cone equipped with a first instance of an elastic member.
[0069] [ Figure 3 ]: Figure 3 a and 3b represent schematic perspective views of the upstream portion of the exhaust cone of the second instance equipped with a resilient member.
[0070] [ Figure 4 ]: Figure 4 express Figure 3 A cross-sectional view of the upstream portion of the exhaust cone.
[0071] [ Figure 5 ]: Figure 5 A cross-sectional view of the upstream portion of an exhaust cone, showing an example equipped with a main airflow recirculation seal.
[0072] [ Figure 6 ]: Figure 6a and 6b represent schematic perspective views of the upstream portion of a modified exhaust cone equipped with a second instance of elastic components.
[0073] [ Figure 7 ]: Figure 7 a and 7b represent schematic perspective views of the upstream portion of a modified exhaust cone equipped with a second instance of elastic components.
[0074] [ Figure 8 ]: Figure 8 a represents a schematic perspective view of the upstream portion of the exhaust cone of the third instance equipped with an elastic member, and Figure 8 b represents Figure 8 A cross-sectional view of the exhaust cone of component a.
[0075] [ Figure 9 ]: Figure 9 A schematic cross-sectional view showing the upstream portion of a modified exhaust cone equipped with a third example of an elastic member.
[0076] [ Figure 10 ]: Figure 10 A schematic perspective view showing the upstream portion of the exhaust cone of the fourth example equipped with an elastic member. Detailed Implementation
[0077] See Figure 2 The nozzle exhaust cone 100 includes an outer annular wall 102 for the flow of the main airflow, for example by bolting to the conical downstream portion 104 of the exhaust cone.
[0078] For example, the outer annular wall 102 is metallic or made of a composite having a ceramic matrix, and the conical downstream portion 104 is made of a composite having a ceramic or metallic matrix.
[0079] A ring-shaped acoustic enclosure 106 is disposed within an outer annular wall 102. The ring-shaped acoustic enclosure 106 includes an inner annular wall 108 radially disposed within the outer annular wall 102, and... Figure 2 The unshown radial arrangement in the text refers to multiple partitions between the outer annular wall 102 and the inner annular wall 108. Other annular boxes may be arranged in this text, which do not consist of annular boxes that ensure acoustic functionality (i.e., reduce turbine air outlet noise).
[0080] For example, the inner annular wall 108 and / or sound zones may be made of metal or a composite material with a ceramic matrix.
[0081] The exhaust cone 100 is connected to the flange 110 of the exhaust housing 109 that carries the nozzle of the exhaust cone 100. Specifically, the inner annular wall 108 is connected to the flange 110 of the exhaust housing 109 via a connecting member 112.
[0082] The connecting member 112 includes an annular flange 114 that engages with a flange 110 of the exhaust casing 109, and a plurality of fastening lugs 116 circumferentially distributed around the longitudinal axis X. Each fastening lug 116 is fastened to an upstream portion of the inner annular wall 108. The fastening lugs 116 may be flexible or rigid. The connecting member 112 may be metallic. The fastening lugs 116 may be bolted to the inner annular wall 108.
[0083] The downstream portion of the outer annular wall 102 can be connected to the downstream portion of the inner annular wall 108, such as... Figure 2 As shown in the diagram. On the other hand, the upstream portion of the outer annular wall 102 is free to move relative to the inner annular wall 108. This arrangement causes the upstream portion of the outer annular wall 102 to deform due to thermomechanical stresses related to the operating temperature of the exhaust cone 100 and differences in the materials within the exhaust cone 100.
[0084] In addition, a plurality of elastic members 118 are radially arranged between the outer annular wall 102 and the connecting member 112 so that prestress is applied radially by the outer annular wall 102 against the inner annular wall 108 or the connecting member 112.
[0085] Radially deformable elastic members 118 are circumferentially distributed around the longitudinal axis X. For example, each elastic member 118 may be formed by a radially deformable blade extending from the annular wall 102 toward the inner annular wall 108 and radially outward axially.
[0086] The elastic member 118 allows force to be distributed between the upstream and downstream interfaces of the outer annular wall 102, thereby reducing the thickness and mass of the outer annular wall 102. Furthermore, the elastic member 118 improves the vibration behavior of the outer annular wall 102.
[0087] The outer annular wall 102 extends to form the continuity of the shroud 111 of the exhaust casing 109.
[0088] exist Figure 3 In the examples a, 3b, and 4, Figure 2 The exhaust cone 100 includes an elastic member 200, which is fastened to the outer annular wall 102 on one hand and pressed against the annular flange 114 of the connecting member 112 on the other. The elastic member 200 is formed of a leaf spring, each leaf spring including a first leaf 2021 extending radially inward from the outer annular wall 102 and in a first direction in the circumferential direction about the longitudinal axis X. Each leaf spring includes a second leaf 2022 extending radially inward from the outer annular wall 102 and in a second direction in the circumferential direction opposite to the first direction. The first and second leaves 202 are flexible and radially deformable.
[0089] A radial displacement limiting member 204, in the form of a buffer 204, is radially arranged between the outer annular wall 102 and the connecting member 112. A predetermined distance 205 is radially maintained between the buffer 202 and the connecting member 112 to form a stop in the event that the outer annular wall 102 undergoes considerable radial deformation (i.e., radial deformation greater than the predetermined distance 205). Each buffer 204 is fastened to the leaf spring 200, particularly at the central portion between the first and second blades 202 of the leaf spring 200. The buffer 204 may be rigid or flexible.
[0090] The buffer 204 can be assembled to or integrally formed with the leaf spring 200.
[0091] The exhaust cone 100 further includes a first seal 206 having an annular shape around the longitudinal axis X, and surrounding both the axial space between the inner annular walls 108 and the circumferential space between the fastening lugs 116. Therefore, the main airflow cannot penetrate into the interior of the exhaust cone 100, which may reduce the performance of the nozzle carrying the exhaust cone 100.
[0092] The first seal 206 is made of a metallic material such as tungsten or a chromium-nickel-iron alloy to withstand the high temperature of the main air.
[0093] The first seal 206 may be formed by multiple corner sections that are connected together and partially overlap.
[0094] The first seal 206 includes a downstream end 208 arranged to press against the inner annular wall 108 and an upstream end 210 arranged to press against the annular flange 114 of the connecting member 112. The upstream end 210 of the first seal 206 can be directly fastened to the annular flange 114 of the connecting member 112.
[0095] The leaf spring 200 contacts the first seal 206.
[0096] Figure 5 Indicates something similar to Figure 3 and 4 The arrangement of the exhaust cone 100. Conversely, Figure 5 The exhaust cone 100 has a second seal 212, which is arranged to radially cover the space between the annular flange 114 of the connecting member 112 and the outer annular wall 102.
[0097] The outer annular wall 102 presses against the second seal 212. The second seal 212 can be fastened to the annular flange 114 of the connecting member 112, or can be arranged to contact the annular flange 114 of the connecting member 112. The second annular seal 212 is metallic and is formed by a plurality of corner sections that are circumferentially distributed around a longitudinal axis and connected together to form the second annular seal 212.
[0098] exist Figure 6 In variations a and 6b, the elastic member 200 is disconnected from the radial displacement limiting member 204. Each elastic member 200 is circumferentially separated from the radial displacement limiting member 204.
[0099] The elastic member 200 and the radial displacement limiting member 204 are directly fastened to the outer annular wall 102 and arranged on the same circumferential row.
[0100] exist Figure 7 In variations a and 7b, the elastic member 200 and the radial displacement limiting member 204 are fastened to the inner annular wall 108, specifically to the first seal 206. The elastic member 200 and the radial displacement limiting member 204 are circumferentially stacked and arranged in the same position.
[0101] See Figure 8 a and 8b, the exhaust cone 100 is equipped with a single annular elastic member 300, which is arranged to contact the inner annular wall 108 on one side and the outer annular wall 102 on the other side.
[0102] The annular elastic member 300 has a downstream end that presses against the inner annular wall 108 and an upstream end 306 that presses against the connecting member 112. The upstream end 306 can also be fastened to the connecting member 112. The annular elastic member 300 includes a radially outwardly extending ridge 304. The outer annular wall 102 presses against the ridge 304.
[0103] The annular elastic member 300 may be metallic and formed by multiple corner sections connected together.
[0104] exist Figure 9 In the variant, a second annular seal 306 is arranged around the annular elastic member 300. The second seal 306 has an upstream end 308 that extends radially outward and abuts against the outer annular wall 102. The second seal 306 also has an upstream end 310 that presses against the flange 114 of the connecting member 112.
[0105] The second seal 306 allows the main airflow to be prevented from seeping into the interior of the inner annular wall 108.
[0106] See Figure 10 The exhaust cone has a plurality of elastic members 400, each having a radially inner end 402 connected to an annular flange 114 of the connecting member 112. Each elastic member 400 further has a blade 404 extending longitudinally and arranged radially at a distance from the radially inner end 402.
[0107] The elastic member 400 further forms a radial displacement limiting member passing through the radially outer end 406. This radially outer end 406 has an edge extending radially inward.
[0108] The exhaust cone may further include an elastic member 400 and a radial displacement limiting member (e.g., radial displacement limiting member 204).
Claims
1. An assembly for a turbine having a longitudinal axis (X), comprising: - An exhaust cone (100) comprising an outer annular wall (102) for the flow of the main airflow and an annular box (106) radially disposed within the outer annular wall, the annular box comprising an inner annular wall (108) radially disposed within the outer annular wall of the exhaust cone. -Exhaust casing (109), which is arranged upstream of the exhaust cone, and - A connecting component (112) is inserted longitudinally between the exhaust casing and the exhaust cone, the connecting component being fastened to the exhaust casing and the inner annular wall. The assembly further includes at least one elastic member (118, 200, 300, 400) that is radially deformable and radially prestressed between the outer annular wall and the connecting member, and The connecting component includes an annular flange connected to a corresponding flange of the exhaust casing, and a plurality of fastening lugs circumferentially distributed around the longitudinal axis and connected to the inner annular wall.
2. The assembly according to claim 1, comprising a member (204) for limiting radial displacement of the outer annular wall (102), the radial displacement limiting member being inserted between the outer annular wall and the connecting member (112), the radial displacement limiting member forming a radial stop against the outer annular wall of the connecting member.
3. The assembly according to claim 1 or 2, characterized in that, The elastic member (200) is fastened to the outer annular wall (102) and in radial contact with the connecting member (112), or fastened to the connecting member (112) and in radial contact with the outer annular wall (102).
4. The assembly according to claim 2, characterized in that, The radial displacement limiting member (204) is fastened to the outer annular wall (102) and radially contacts the connecting member (112), or is fastened to the connecting member (112) and radially contacts the outer annular wall (102).
5. The assembly according to claim 2, characterized in that, At least one elastic member (118, 200, 300) is superimposed on a radial displacement limiting member (204).
6. The assembly according to claim 2, characterized in that, At least one elastic member (118, 200, 300) is circumferentially separated from one of the radial displacement limiting members (204).
7. The assembly according to claim 1 or 2, characterized in that, At least one elastic member (118, 200, 400) is a leaf spring, which is circumferentially distributed around the longitudinal axis.
8. The assembly according to claim 7, characterized in that, At least one of the leaf springs (200) includes a first flexible blade (2021) extending in a first direction about the longitudinal axis in the circumferential direction, and a second flexible blade (2022) extending in a second direction about the longitudinal axis (X) in the circumferential direction opposite to the first direction.
9. The assembly according to claim 7, characterized in that, At least one of the leaf springs (400) includes a single blade (404) that extends radially along the longitudinal axis (X).
10. The assembly according to claim 9, characterized in that, At least one of the leaf springs (400) forms a radial displacement limiting member.
11. The assembly according to claim 1 or 2, comprising a first annular seal (206) surrounding the interface between the connecting member (112) and the inner annular wall (108), the first annular seal (206) being configured to restrict the circulation of the main airflow toward the cavity of the exhaust cone.
12. The assembly according to claim 1 or 2, comprising a second annular seal (212) connected to the connecting member (112) and extending radially toward the outer annular wall (102), the second annular seal (212) being configured to prevent the main airflow from passing through the outer annular wall (102).
13. The assembly according to claim 1 or 2, characterized in that, The elastic member (300) is formed of an annular seal that is fastened to the connecting member (112) and includes a radially deformable portion abutting against the outer annular wall (102).
14. The assembly according to claim 2, characterized in that, Each displacement limiting member (204) is formed by a buffer that is circumferentially distributed around the longitudinal axis (X) and maintains a predetermined distance from the connecting member (112) in the radial direction.
15. The assembly according to claim 1 or 2, characterized in that, The downstream portion of the outer annular wall (102) is fastened to the downstream portion of the inner annular wall (108).
16. A turbine nozzle comprising the assembly according to any one of the preceding claims.