Turbine engine nozzle ring for an aircraft

Abstract

The turbomachine sub-assembly comprises: - at least one low-pressure nozzle ring comprising a root (38) integral with the nozzle ring; - a clamping portion (40) configured to fasten the root to a casing of the turbomachine; and - at least two pads (150) interposed between the root and the clamping portion, each pad being assembled in a form-fit manner with one of the root or the clamping portion.

Description

Technical Field

[0001] This invention relates to turbines, such as aircraft turbojet engines. Background Technology

[0002] A dual-flow turbojet engine for aircraft is known, which includes a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, and a low-pressure turbine. The low-pressure turbine recovers a portion of the energy generated by gas combustion for the operation of the fan, compressor, and accessories.

[0003] The components that make up a low-pressure turbine include movable blades and a low-pressure nozzle ring. Gas expands within the low-pressure nozzle ring. This accelerates and deflects the flow. This flow causes the turbine rotor to spin, thus forming the impeller.

[0004] This invention falls within the scope of solutions to a recurring problem observed in the nozzle ring of the first stage of a low-pressure turbine. The nozzle ring is formed by elements sequentially positioned circumferentially around an axis. In fact, each element is characterized in that it is fixed from top to bottom. The problem concerns the lower portion of the element (i.e., the bottom of the lower platform), more precisely the root or support of the nozzle ring element. This root is used to secure the component by clamping. However, on the one hand, this contact generates wear through friction (or fretting wear), and on the other hand, this area is exposed to the risk of secondary corrosion caused by sulfur during operation. Therefore, the combination of these two factors results in contact corrosion, which can severely damage the component.

[0005] Therefore, numerous corrosion protrusions have been observed at the root of the nozzle ring element in the fleet and during durability testing. In the fleet, this condition could lead to engine removal. In durability testing, once the equivalent of 6200 durability cycles had been performed, corrosion was allowed at the root of the nozzle ring element in 17% of the components.

[0006] To prevent corrosion, a coating could be applied to the component. However, due to friction, this coating will not last long in the area.

[0007] Engine manufacturers strive to ensure component operation and minimize engine removal. During engine inspections, wear and tear can lead to the replacement of expensive parts. Furthermore, the duration of operation is not negligible (e.g., due to the need to disassemble the entire turbine module for component replacement and then reassemble).

[0008] Therefore, one object of the present invention is to facilitate turbine maintenance and reduce its cost when dealing with this contact corrosion phenomenon. Summary of the Invention

[0009] Therefore, according to the present invention, a turbine sub-assembly is provided, the sub-assembly comprising:

[0010] - At least one low-pressure turbine nozzle ring, the nozzle ring including a root integral with the body of the nozzle ring,

[0011] - Clamping part, the clamping part is configured to attach the root to the turbine housing, and

[0012] - At least two pads are inserted between the root and the clamping part.

[0013] Each pad is assembled with one of the root and clamping parts in a shape-fitting manner.

[0014] Therefore, it is the pad, not the root, that contacts the clamping part. Thus, the pad protects the root from friction and contact corrosion. If the pad is damaged or worn, replacing it with a new pad is sufficient, which is less costly than replacing the nozzle ring element itself. Therefore, this invention avoids the coupling effect of wear and corrosion. If the root is covered with an anti-corrosion coating, this coating protects the root in the contact area. This invention does not eliminate wear, but it enables rapid assessment of wear while preventing the exacerbating combination of wear and corrosion, and allows for quick replacement of worn parts. This invention enables reduced maintenance costs because fewer parts need to be replaced and less turbine removal is required. This invention also enables improved machine performance because placing a new pad during inspection ensures less leakage. Therefore, this invention enables control of phenomena previously experienced by the blades.

[0015] It can be specified that each pad is assembled to the root or clamping part in a shape-fitting manner.

[0016] It can be specified that each pad is formed of a material different from the root material, such as a tungsten-chromium-cobalt alloy, or each pad may even be formed of a material less hard than the root material, such as carbon or graphite.

[0017] It can also be specified that each pad is made of the same material as the root.

[0018] Subcomponents may also have at least one of the following characteristics:

[0019] -The clamping part does not have jaws, but has a main surface that contacts the pad;

[0020] - The pads form the clamping jaws of the gripping part;

[0021] - The sub-assembly includes at least one protrusion, such as at least two protrusions, on one of the root and the clamping portion, the protrusions being configured to penetrate into the cavity of the other of the root and the clamping portion;

[0022] - The protrusions, or each protrusion, have a rectangular parallelepiped shape;

[0023] - The number of pads is two;

[0024] - There are four pads, and the root has two faces. Each face is in direct contact with two pads, and the two pads in direct contact with each face are spaced apart from each other.

[0025] - Each pad has a wear indicator;

[0026] - The clamping part includes jaws that contact the pad;

[0027] - The pad is directly attached to the jaws of the clamping part;

[0028] - Each pad extends only towards the root; and

[0029] - The root has an anti-corrosion coating.

[0030] The invention also provides a turbine, such as an aircraft turbojet engine, the turbine including sub-components according to the invention.

[0031] Furthermore, according to the present invention, a method for manufacturing a turbine, such as an aircraft turbojet engine, is provided, comprising:

[0032] - The two pads are assembled to one of the root and clamping parts of the low-pressure turbine nozzle ring using a form-fitting method, with the root being integral with the body of the nozzle ring.

[0033] - Attach the clamping part to the root, such that the pad is inserted between the root and the clamping part, and

[0034] - Attach the clamping part to the turbine housing.

[0035] Finally, according to the present invention, a method for maintaining a turbine, such as an aircraft turbojet engine, is provided, comprising:

[0036] - The first pad inserted between the low-pressure turbine nozzle ring and the clamping part is removed. The clamping part is configured to attach the root to the turbine housing.

[0037] The root is integrated with the main body of the nozzle ring.

[0038] - Instead of the first pad, the second pad is assembled with one of the root and clamping parts in a form-fit manner, and

[0039] - Attach the clamping part to the root so that the second pad is inserted between the root and the clamping part. Attached Figure Description

[0040] Embodiments of the invention will now be presented by way of non-limiting examples supporting the accompanying drawings, in which:

[0041] - Figure 1This is a partial axial cross-sectional view of an aircraft turbojet engine forming the machine according to the present invention;

[0042] - Figure 2 yes Figure 1 An enlarged view of a portion of a turbojet engine;

[0043] - Figure 3 yes Figure 1 A perspective view of the nozzle ring of the machine;

[0044] - Figures 4 to 6 It shows that Figure 3 The view of the nozzle ring attached to the machine housing;

[0045] - Figure 7 and Figure 8 The images show a side view and a perspective view of the nozzle ring being attached to the housing in a first embodiment of the invention.

[0046] - Figures 9 to 11 This is a similar view showing the second embodiment;

[0047] - Figure 12 A variant embodiment is shown; and

[0048] - Figures 13 to 16 Is with Figure 7 and Figure 8 A similar view shows two other embodiments. Detailed Implementation

[0049] Figure 1 An aircraft turbojet engine 1 according to the present invention is shown. This is a turbojet engine, which is configured as a dual-flow, dual-shaft turbine. The turbine has a main axis XX.

[0050] The turbine runs from upstream to downstream (therefore in) Figure 1 (From left to right) It includes a fan 2, a low-pressure compressor 4, a high-pressure compressor 6, a combustion chamber 8, a high-pressure turbine 10, and a low-pressure turbine 12. These components have parts that can rotate about axis XX.

[0051] Compressors 4 and 6, combustion chamber 8, and turbines 10 and 12 define the primary airflow. Nacelle 16 surrounds fan 2 to form a fan compartment and define the secondary airflow.

[0052] Typically, the airflow entering the turbine at the air inlet is compressed, then mixed with fuel and burned in the combustion chamber 8. The combustion gases enable one or more turbine rotors to rotate about their axes. For example, the high-pressure turbine 10 drives the high-pressure compressor 6, and the low-pressure turbine 12 drives the low-pressure compressor 4 and the fan 2. Generally, the terms upstream and downstream refer to the flow of air within the turbine from its inlet to its outlet.

[0053] The stationary parts of the turbine specifically include housings, such as turbine housing 22, which is an intermediate housing inserted between the high-pressure turbine and the low-pressure turbine and housed within the respective housings of the high-pressure turbine and the low-pressure turbine.

[0054] Each of the high-pressure turbine and the low-pressure turbine comprises multiple stages, each stage having a nozzle ring fixed relative to the housing, thereby receiving and rectifying the airflow to apply it to an impeller rotating in a given direction.

[0055] The following description focuses on the low-pressure nozzle ring 24 located at the inlet of the low-pressure turbine 12, i.e., the nozzle ring upstream of the turbine. This low-pressure nozzle ring is located downstream of the fluid rectifier (or the TCF housing for the turbine center frame) of the high-pressure turbine 10, for example, directly downstream of the rectifier, or downstream of the impeller itself downstream of the rectifier. Therefore, the nozzle ring 24 corresponds to the first stage of the fixed blades of the low-pressure turbine. Alternatively, the nozzle ring 24 may be located downstream of the low-pressure turbine, or at another turbine.

[0056] The nozzle ring 24 has an annular shape centered on the axis XX. This nozzle ring is formed by nozzle ring sectors or elements 25. (Refer to...) Figure 3 Each element 25 includes a body having an inner (or lower) platform 32 or inner shroud, an upper (or outer) platform 34 or outer shroud, and a plurality of blades 36 extending radially between and connected to the platforms 32 and 34. The upper platform 34 is further away from the axis than the lower platform 32.

[0057] On the outside of the upper platform 34, the nozzle ring element 25 is connected to the housing in a conventional manner, which will not be described further.

[0058] Inside the inner platform 32, the nozzle ring element 25 continues from a root 38 that projects radially from the platform. Specifically, as... Figure 4 As shown, the root has a flat shape located in a plane perpendicular to the axis. The root is integral with the body of the nozzle ring element 25. The root has a known anti-corrosion coating.

[0059] The machine also includes a clamping portion 40 for each nozzle ring element 25, which is configured to attach the root 38 to the housing 22. (As...) Figure 6 As specifically shown, the clamping part includes two branches 42, each having two main surfaces 44 facing each other. The clamping part is designed to clamp the root between the two branches along the direction of axis XX.

[0060] The clamping portion 40 is connected to the turbine housing by means of an annular flange 46. Therefore, the flange is configured to be securely connected to the fixed portion of the turbine and the root 38 of the nozzle ring element. Here, a secure connection between the two components means that a movement of one component according to a degree of freedom relates to the same movement of the other component according to the same degree of freedom. A secure connection is, for example, an attachment. This connection ensures the retention of the root 38 of the nozzle ring element 25. This connection also allows for the separation of the upstream and downstream portions of the region located below the root 38.

[0061] Therefore, flange 46 is configured to separate the upstream and downstream portions of the region located below root 38 to prevent any fluid flow below the root. The flange extends to separate the upstream and downstream chambers located upstream and downstream of root 38, respectively. The upstream chamber is disposed between the turbine housing and the flange. Thus, the sealing flange allows, for example, the flow of hot air over certain downstream components (typically the turbine disk). The flange is designed to limit heat transfer from the upstream chamber, particularly from the fluid flow path, to the flange through convection, conduction, and / or radiation.

[0062] The clamping portion 40 forms a receiving portion, thereby allowing the clamping portion and the root portion to move radially relative to each other during operation without the risk of the root portion disengaging from the clamping portion 8. The clamping portion restricts the relative translational movement of the clamping portion and the root portion along the axis XX.

[0063] Several embodiments of the cooperation between the root and the clamping part will now be presented.

[0064] First Embodiment

[0065] This embodiment is in Figure 7 and Figure 8 As shown in the image.

[0066] Here, the base has four 150 pads. Figure 7 In the middle, two pads are hidden by the pads in the foreground. Figure 8 In the middle, the two pads are hidden at the base.

[0067] Here, each pad has the shape of a strip or track. The strips have a longitudinal direction that is parallel to each other and close to the radial direction.

[0068] The root has two opposing surfaces 52. Each of these opposing surfaces is in direct contact with two pads 150. (Example) Figure 8 As shown, on each surface, the two pads that are in direct contact with this surface are spaced apart from each other along the circumferential direction of axis XX.

[0069] Each pad 150 is assembled to the root 38 in a form-fit manner. For example, each pad includes three protrusions projecting from the surface of the pad that contacts the root, as in the second embodiment. Figure 11 As shown. The protrusion is configured to penetrate into a corresponding cavity provided for this purpose in the root. Alternatively, it can be specified that the protrusion is located on the clamping part and the cavity is located in the root.

[0070] As shown in the figure, each pad 150 is inserted between the root and the clamping part. Therefore, each branch of the clamping part is supported on the root by the jaws of the branch, and only contacts the two roots at the same time.

[0071] Therefore, additional material is formed on both sides of the root to accommodate the clamping portion. Thus, friction occurs on these strips, which can wear down and subsequently be repaired.

[0072] Each pad 150 can be formed of the same material as the nozzle ring element 25, such as a metal alloy. Each pad can also be formed of a different material than the root material, such as a tungsten-chromium-cobalt alloy. Tungsten-chromium-cobalt alloy is a metal alloy whose main component is cobalt, and the main alloying element is chromium. It may also contain small amounts of tungsten or molybdenum and a small but significant amount of carbon. Tungsten-chromium-cobalt alloys exhibit good resistance to contact friction.

[0073] During the manufacture of the turbojet engine, the pad 150 is assembled to the clamping part in a form-fit manner. The clamping part is then attached to the root, such that the pad is inserted between the root and the clamping part, and the clamping part is attached to the housing 22 by means of a flange. The assembly, which is clamped by the force of the clamping part on the pad, ensures that the pads are secured to the root.

[0074] During turbojet engine maintenance, if the pads 150 wear out, they are removed by detaching them from the root. New pads are then assembled in place of the root in a form-fit manner, with the clamps attached to the root so that the new pad is inserted between the root and the clamps. Replacement may also involve only one pad, or multiple pads, rather than all of them.

[0075] Each pad may be specified to have a wear indicator, for example, in the form of a mark 53 located on the side or edge of the pad. When this mark is dented or disappears, it is a signal that the pad must be replaced. This type of wear indicator quickly and effectively shows whether the wear is acceptable. In the case of an excessively worn pad, as described above, it is sufficient to replace it by removing it from the insertion and inserting a new pad.

[0076] Thanks to this invention, the root of the nozzle ring element retains its anti-corrosion coating intact, and friction is controlled.

[0077] In the following embodiments and variations, common components will no longer be described. The descriptions will apply only to the different features.

[0078] Second Embodiment

[0079] This embodiment is in Figures 9 to 11 As shown in the image.

[0080] This time, the quantity of pad 250 is two. Independent of the subsequent features, this feature can be applied to the first embodiment.

[0081] This time, each pad 250 is fitted to the clamping part 40 in a shape-fit manner, and is more precisely fitted to the jaws of the clamping part's branches. Figure 11 A pad 250 with protrusions 60 is shown facing cavities 62, which are designed to receive the protrusions in a clamping portion.

[0082] Additionally, but independently, each pad 250 is formed of a material with a lower hardness than the material at the root, such as carbon or graphite, tungsten-chromium-cobalt alloy, or equivalent material. Therefore, this material can wear or erode during friction in operation, thereby reducing contact friction.

[0083] This embodiment has the advantage of being easier to implement because less material needs to be provided in the clamping portion. Additionally, it eliminates the need to modify the root of the nozzle ring element 25 and avoids the risks associated with applying an anti-corrosion coating to the nozzle ring. Furthermore, it simplifies the geometry of the root because it eliminates the need to provide one or more cavities within the root.

[0084] Variant

[0085] This variant is in Figure 12 As shown in the image.

[0086] This variant is based on the second embodiment.

[0087] Here, protrusion 60 is unique and independent of it, having an elongated rectangular parallelepiped shape. Cavity 62 has a concave shape that complements this protruding shape.

[0088] Third Embodiment

[0089] This embodiment is in Figure 13 and Figure 14 As shown in the image.

[0090] In this embodiment, there are two pads 350, located at the root. Each face 52 of the root has a single pad, which is in the form of a strip extending circumferentially along the axis. The strip has a shape and position corresponding to the support area of ​​the clamping part on each face 52.

[0091] Independently, the clamping part does not have claws. The main surface 44 of the branch 42 of the clamping part is in direct contact with the pad. In fact, it can be understood that in this type of arrangement, the claws of the clamping part become useless.

[0092] The advantage of this solution is that it simplifies the geometry of the clamping part. This solution also increases the support surface of the clamping part on each face and makes sliding between the nozzle ring and the flange more difficult. Therefore, this solution reduces friction and delays the necessary replacement of the pad.

[0093] Fourth embodiment

[0094] This embodiment is in Figure 15 and Figure 16 As shown in the image.

[0095] This time, two pads 450 are attached to the clamping part and form the jaws of the clamping part, while protruding from the branch along the root direction.

[0096] Many modifications may be made to this invention without departing from its scope.

[0097] This solution is advantageous for all contact interfaces between the two components, as this would lead to wear on at least one component and potential corrosion. For example, this solution could be considered to replace the tungsten-chromium-cobalt alloy in the impeller's collar. In particular, an advantage of this invention is that it allows for easy replacement of the gasket over time.

Claims

1. A turbine subassembly, the subassembly comprising: - At least one low-pressure turbine (12) nozzle ring (24), the nozzle ring including a root (38) integral with the body of the nozzle ring. - A clamping part (40), the clamping part being configured to attach the root portion to the turbine housing (22), and - At least two pads are inserted between the root and the clamping portion, each pad being assembled with one of the root and the clamping portion in a form-fitting manner.

2. The sub-component according to claim 1, wherein, Each pad is assembled to the root (38) in a shape-fitting manner.

3. The sub-component according to claim 2, wherein, Each pad is formed of a material different from that of the root (38).

4. The sub-component according to claim 2, wherein, The clamping part (40) does not have claws, and the clamping part has a main surface (44) that contacts the pad.

5. The sub-component according to claim 1, wherein, Each pad is assembled to the clamping part (40) in a form-fit manner.

6. The sub-component according to claim 5, wherein, Each pad is formed of a material with a lower hardness than the material of the root (38).

7. The sub-component according to claim 5, wherein, The pad forms the jaws of the clamping part (40).

8. The sub-component according to claim 1, wherein, The sub-assembly includes at least one protrusion (60) on one of the root (38) and the clamping portion (40), the protrusion being configured to penetrate into a cavity (62) of the other of the root and the clamping portion.

9. The sub-component according to claim 8, wherein, The protrusion (60) has the shape of a rectangular parallelepiped.

10. The sub-component of claim 1, wherein, The number of pads is two.

11. The sub-component of claim 1, wherein, The number of pads is four, and the root (38) has two surfaces (52), each surface being in direct contact with two pads, and the two pads in direct contact with each surface being spaced apart from each other.

12. The sub-component according to claim 1, wherein, Each pad has a wear indicator (53).

13. The sub-component according to claim 3, wherein, Each pad is formed from a tungsten-chromium-cobalt alloy.

14. The sub-component of claim 6, wherein, Each pad is formed from carbon or graphite.

15. The sub-component of claim 8, wherein, The sub-assembly includes at least two protrusions on one of the root (38) and the clamping portion (40).

16. A turbine comprising the sub-component according to claim 1.

17. The turbine according to claim 16, wherein, The turbine is an aircraft turbojet engine (1).

18. A method for manufacturing a turbine, the method comprising: - The two pads are assembled in a form-fit manner to one of the root (38) and the clamping part (40) of the low-pressure turbine (12) nozzle ring (24), the root being integral with the body of the nozzle ring. - Attach the clamping part (40) to the root such that the pad is inserted between the root (38) and the clamping part (40), and - Attach the clamping part (40) to the housing (22) of the turbine.

19. The method according to claim 18, wherein, The turbine is an aircraft turbojet engine (1).

20. A method for maintaining a turbine, the method comprising: - The first pad inserted between the root (38) and the clamping part (40) of the nozzle ring (24) of the low-pressure turbine (12) is removed, the clamping part being configured to attach the root to the turbine housing (22), the root being integral with the body of the nozzle ring. - Instead of the first pad, the second pad is assembled with one of the root (38) and the clamping portion (40) in a form-fit manner, and - Attach the clamping part to the root such that the second pad is inserted between the root and the clamping part.

21. The method according to claim 20, wherein, The turbine is an aircraft turbojet engine (1).

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