Sealing gasket for aircraft turbomachine

Abstract

The invention relates to a seal for an aircraft turbine engine, comprising a plurality of seal segments (20) distributed circumferentially about a longitudinal axis (X), each seal segment (20) comprising a radially inner annular wall segment (22) and a radially outer annular wall segment (24) interconnected by an elastically deformable member (26), where each radially inner annular wall segment (22) is connected to an inner radial leg (28), and each radially outer annular wall segment (24) is connected to an outer radial leg (28). And each radially outer annular wall section (24) is connected to an outer radial leg (24), the inner leg (28) and the outer leg (30) being interconnected by means of an elastically deformable member (26) consisting of a stack of a plurality of contiguous elastic strips (32).

Description

Technical Field

[0001] This disclosure relates to an annular seal, such as a hydrostatic annular seal. This document also relates to an assembly including such a seal, and a turbine or turbine engine including such a seal. Background Technology

[0002] Figure 1 A turbine engine is schematically shown, which is a turboprop engine 1 with a longitudinal axis X. Along the upstream AM to downstream AV direction of the gas flow within the turbine engine 1, the turbine engine 1 typically includes: a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, a low-pressure turbine 7, and an exhaust system downstream of the turbine engine 1. The gas flow, particularly air, entering upstream of the turbine engine 1 first passes through the fan 2 and then splits into an annular flow path called the core flow 8 and an annular flow path surrounding the core flow 8 called the bypass flow 9. The low-pressure compressor 3, the high-pressure compressor 4, the combustion chamber 5, the high-pressure turbine 6, and the low-pressure turbine 7 are all arranged within the core flow 8.

[0003] In this document, the terms "longitudinal," "radial," and "circumferential" are defined relative to the longitudinal axis X of the turbine engine 1, which is the same as the axis of rotation of the low-pressure and high-pressure rotors of the turbine engine 1. The terms "inner" and "outer," as well as "inner side" and "outer side," are defined in the radial direction relative to the longitudinal axis X. The terms "upstream" and "downstream" are defined relative to the overall flow direction of gas within the turbine engine along the longitudinal axis X, around which the turbine engine extends.

[0004] Now for reference Figure 2 A schematic view of a portion of a low-pressure turbine 7 having a longitudinal axis, the turbine comprising alternating annular rows of moving blades 9 and annular rows of stator blades 10 arranged longitudinally alternately. Figure 2 Only two rows of annular rotor blades 9 and one annular row of stator blades 10 are shown. The annular rows of rotor blades 9 or moving blades 9 are interconnected by a cylindrical cover 11.

[0005] Each stator blade 10 annular row includes a radially inner annular platform 12 and a radially outer annular platform (not shown), with a plurality of blades 13 extending between the two. The radially outer annular platform is connected to the turbine casing.

[0006] Managing the seal between the stator blade 10 end and the rotor shroud 11 is crucial for limiting gas leakage between the rotor and stator 10, as well as controlling pressure and temperature conditions on both sides of the seal and in the area below it. For this purpose, it is known to provide a radially annular diaphragm 14 extending inward from a radially inner annular platform, with a seal 15 mounted at one end. This seal is designed to maintain a small gap with the corresponding shroud of the rotor during operation to reduce airflow through the seal 15 during operation. (Reference) Figure 2 C. The hydrostatic annular seal 15 preferably comprises a ring 15a extending radially outward from the radially outer annular wall 24. For example, the ring 15a may have a U-shaped cross-section, consisting of two longitudinally spaced arms, with a radial partition 14 disposed between the two arms. The two arms of the U-shaped ring and the radial partition 14 may be positioned relative to each other by a centering pin.

[0007] Therefore, such as Figure 2 As shown in A and 2B, the stator blades 10 annular row is equipped with a clearance-controlled annular seal 15, which is radially arranged on the inner side of the stator blades 10 annular row and the outer side of the cylindrical cover 11. The clearance-controlled annular seal 22 cooperates with the cylindrical cover 11 in a non-contact sealing manner to reduce the flow rate from upstream to downstream of the stator blades 10 annular row in the annular space between the seal 15 and the cylindrical cover 11.

[0008] In particular, this clearance-controlled seal 15 operates with a small and controlled annular gap between the seal and the cover 11 during turbine operation. Furthermore, this type of seal is designed to adapt to the gap during operation. Using the hydrostatic seal 15 thus has the advantage of reducing leakage flow at the seal, and therefore improves the performance of the turbine engine and reduces the requirements for thermal and mechanical stress when designing the various components of the turbine 7.

[0009] like Figure 2 As shown in Figure B, the hydrostatic annular seal 15 can be composed of two concentric annular walls 16, 17 and a plurality of circumferentially adjacent elastic deformable members extending between the two walls 16, 17, particularly including circumferentially extending elastic deformable blades 18. For example, such a seal is described in document WO 2009 / 148787. This configuration allows for improved control of radial deformation of the seal 15, and thus improves clearance control between the seal 15 and the cover 11 that mates with the seal 15, thereby reducing air passage.

[0010] This document aims to provide a simple, reliable, and economical solution to meet this need. Summary of the Invention

[0011] This document relates to a seal for an aircraft turbine engine, comprising a plurality of sealing segments circumferentially distributed around a longitudinal axis. Each sealing segment includes a radially inner annular wall segment and a radially outer annular wall segment interconnected by an elastically deformable member. Each radially inner annular wall segment is connected to an inner radial leg, and each radially outer annular wall segment is connected to an outer radial leg. The inner and outer legs are interconnected by the elastically deformable member, which is composed of a stack of a plurality of adjacent elastic strips.

[0012] Adjacent strips are used to form elastic deformation members, which can connect the radially inner annular wall segment to the radially outer annular wall segment. Thus, the radially inner annular wall segment can move radially in a controlled manner by means of its radial stiffness through the bending deformation of the elastic deformation member. When it is positioned opposite the rotating cylindrical cover, it can maintain robustness while resisting the torsional and axial forces generated by the pressure difference between the upstream and downstream of the seal.

[0013] The flexible abutment strip can be detached from the inner and outer supports, facilitating direct replacement of the failed sealing section during maintenance. In fact, only the abutment strip, or the abutment strip and the radial inner wall section, needs to be removed, without replacing the entire annular seal, thus reducing the cost of using this type of seal.

[0014] The radial stiffness of the seal can be easily adjusted simply by changing the number and thickness of the strips, and this can be accomplished through analysis.

[0015] This sealing structure allows for operation at low stiffness without encountering the minimum thickness manufacturing challenges achievable through conventional machining (milling, turning, etc.) or specialized processes (EDM, etc.). In fact, the strip can be obtained from rolled sheet metal, whose manufacturing process allows for precise thickness control.

[0016] Furthermore, non-compliant sealing sections can be avoided, as seal stiffness is not achieved through machining, which could result in out-of-tolerance parts. In this system, the radial stiffness of the seal is directly related to the strip stacking. The strip thickness and tolerance range are known before assembly, allowing selection of the combination of strip thicknesses to achieve the target stiffness.

[0017] Another effect of stacked strips is that when the component is subjected to bending (tension-compression), differential micro-displacements occur between the strips and their radially adjacent strips. This stems from the fact that while the overall deformation manifests as the bending of a beam, within each sheet, the free edges at the interfaces experience stresses in opposite directions: one side under tension, the other under compression. Differential displacement occurs under both static and modal deformation. Therefore, this architecture allows the strips to rub against each other, generating damping through energy dissipation. This damping improves the dynamic characteristics of the seal by suppressing the amplitude of modal deformation.

[0018] Finally, the design is radially compact, facilitating the integration of the seal into its working environment.

[0019] According to another feature, at least one of the inner radial support leg and the outer support leg includes a slot, the circumferential end of each strip is longitudinally engaged in the slot, and the strip is radially held within the slot.

[0020] According to another feature, each of the inner radial leg and the outer radial leg includes a slot, the circumferential end of each strip is longitudinally engaged in the slot, and the strip is radially held within the slot.

[0021] According to another feature, the inner radial support leg of the sealing section includes a circumferentially through hollow region, the circumferential end of each strip engaging in the hollow region, and a locking member passing through the thickness of the strip to secure the strip to the radially inner annular wall section.

[0022] In one specific embodiment, the locking member may be a pin that passes through the radially inner annular wall section and the inner radial support leg.

[0023] According to another characteristic, the circumferential dimension of the strip is larger than the thickness and longitudinal dimension of the strip, which makes the strip exhibit mechanical deformation characteristics similar to those of a beam.

[0024] According to another feature, the strips can be fixed to each other at their circumferential ends and to the inner radial legs and the outer radial legs.

[0025] Therefore, these strips have no connection between their circumferential ends that connect to the inner radial legs and the outer radial legs.

[0026] The absence of any connection between the circumferential ends of the strips allows for greater flexibility than a single blade with the same thickness as the total thickness of all strips.

[0027] According to another feature, the elastic deformation member comprises 2 to 40 stacked strips, preferably 2 to 30.

[0028] According to another feature, each strip has a thickness between 0.05 and 5 mm and a longitudinal width between 5 and 50 mm.

[0029] According to another feature, the strip is made of metal and is welded to the radial leg at its circumferential end.

[0030] According to another feature, the radially outer annular wall segment can form a single annular wall, and the radially inner annular wall segment is arranged end-to-end in the circumferential direction.

[0031] This document also relates to a turbine, for example for use in an aircraft, which includes a rotor and a casing, a distributor mounted in the casing that carries the aforementioned seals, and a rotor that includes a cylindrical shroud that rotates about a longitudinal axis and is radially arranged below the distributor.

[0032] This document also relates to a turbine engine that includes the aforementioned seal or the aforementioned turbine. Attached Figure Description

[0033] [ Figure 1 A schematic cross-sectional view of an example turbine engine is shown.

[0034] [ Figure 2 This schematically illustrates a partial view of a turbine (e.g., a low-pressure turbine). Figure 2 B is Figure 2 An enlarged view of the seal shown in Figure A;

[0035] [ Figure 2 C] and Figure 2 Similarly, A shows the connection method between the seal and the stator;

[0036] [ Figure 3 This shows a schematic cross-sectional view of a sealing section with adjacent strips according to this document;

[0037] [ Figure 4 This shows a schematic view of a radial support leg according to a variation;

[0038] [ Figure 5 This document illustrates three different embodiments, A, B, and C, of ​​sealing strips intended to form an elastically deformable member for a seal according to this document.

[0039] [ Figure 6 This illustrates a variant connection method for adjacent strips;

[0040] [ Figure 7 This document illustrates four different embodiments of the sealing strip according to this document. Detailed Implementation

[0041] For reference Figure 3Figure A illustrates a seal 19 for a turbine engine (e.g., for an aircraft), comprising a plurality of sealing segments 20 circumferentially distributed around a longitudinal axis X. Each sealing segment 20 includes a radially inner annular wall segment 22 and a radially outer annular wall segment 24 interconnected by a resilient deformable member 26, wherein each radially inner annular wall segment 22 is connected to an inner radial support leg 28, and each radially outer annular wall segment 24 is connected to an outer radial support leg 30. The inner support leg 28 and the outer support leg 30 are interconnected by the resilient deformable member 26, which is composed of a stack of a plurality of adjacent resilient strips. Here, the outer annular wall is a single unit, but it may also be composed of multiple sector segments.

[0042] The inner support leg 28 extends radially outward from the radially inner annular wall section 22, and the outer support leg 24 extends radially inward from the radially outer annular wall section 24. The radially outer ends of the inner radial support leg 28 and the radially outer annular wall section 24 are spaced apart. The radially inner ends of the outer radial support leg 30 and the radially inner annular wall section 22 are spaced apart. During operation, the radially inner wall section 22 and the inner radial support leg 28 move radially due to the bending of the elastic deformation member.

[0043] like Figure 3 As shown in Figure B, the elastically deformable member 26 thus comprises a stack of a plurality of adjacent strips 32. The strips are in contact with each other but are fixed to each other only at their connecting ends, which are connected to the inner radial leg 28 and the outer radial leg 30. The radial stiffness of each sealing segment can be easily adjusted by changing the number and thickness of the strips, and can be analytically calculated. The strips may be made of sheet metal, and their dimensional characteristics can be determined as follows.

[0044] The circumferential dimension of the strip is sufficiently larger than its radial and longitudinal dimensions, enabling the strip to function as a bending beam. The length-to-width ratio is preferably greater than 2, and / or the length-to-thickness ratio is greater than 10.

[0045] The stiffness of the flexible arm can be calculated analytically, using the following formula:

[0046]

[0047] Where E is the Young's modulus (MPa) of the single-component material of the blade, l is the blade width (mm), e is the blade thickness (mm), N is the number of blades, and L is the blade length (mm).

[0048] When all strips are subjected to bending (tension-compression), the stacked strips 32 will generate differential micro-displacements between strip 32 and its radially adjacent strips. This is because the overall deformation is indeed beam bending, but within each individual strip, the free edges of the interface are subjected to opposite stresses: one side is under tension, and the other side is under compression. Differential displacements occur under both static and modal deformation. Therefore, this structure allows the strips to rub against each other, generating damping through energy dissipation. This damping improves the dynamic behavior of the seal by reducing the modal deformation amplitude.

[0049] The strips 32 are fixed to each other at their circumferential ends and to the inner support leg 28 and the outer support leg 30. Therefore, the strips have no connecting parts outside their circumferential ends, but are only adjacent to each other.

[0050] In one embodiment, strip 32 is made of metal strip, such as steel, titanium, aluminum alloy, cobalt-based alloy, or nickel-based alloy. The strip may be welded to a radial leg at its circumferential end. Each strip may have a thickness between 0.05 and 5 mm and a longitudinal width between 5 and 50 mm. The elastic deformation member may include 2 to 40 strips, preferably 2 to 30.

[0051] At least one of the inner radial support leg 28 and the outer radial support leg 30 may include a slot 34, in which the circumferential end of the strip 32 is longitudinally engaged, and the strip 32 is radially retained within the slot 34. Figure 4 The groove 34 on the inner radial support leg 28 is shown. The outer radial support leg 30 may also form the same groove. Furthermore, if the annular seal 26 fails, the strip 32 assembly can be easily removed and replaced, reducing maintenance time and the number of parts to be replaced. The groove 34 may be longitudinally open to allow for the installation of the strip (…). Figure 4 A). An axial locking plate may be provided on the surface of the inner radial wall 28 and / or the outer radial wall 30 having the slot 34 opening. The open end (i.e., its upstream end) of the slot 34 may be closed by a piece 29 fixed to the upstream surface of the inner radial leg 28. This piece 29 may be fixed by welding or brazing. In another embodiment, as Figure 4 As shown in B, the slot 34 may not be open in the longitudinal direction.

[0052] In another embodiment of the invention, the inner radial support leg 28 of the sealing section may include a circumferentially through hollow region 36 or an opening, the circumferential end of the strip 32 is engaged with the hollow region 36, and the locking member 38 longitudinally and circumferentially locks the strip 32 between the radially inner annular wall sections 22. Figure 6 In practice, the strip 32 can extend circumferentially to both sides of the inner radial support leg 28 and be locked to the support leg 28 by the member 38. The locking member 38 can be a rod that is inserted into the hole of the inner radial support leg 28 and the hole of the strip 32.

[0053] Figure 5 This demonstrates various connection methods between the strip and the legs. Figure 5 This illustrates three types of strips 32a, 32b, and 32c. Strip 32a is rectangular and has two holes 40 (at its ends). Strip 32b is rectangular and has two lugs or tabs 42, each lug or tab having a hole 40, the tabs being formed at the circumferential ends of strip 32b. Strip 32c is rectangular and identical to strip 32b, but the lugs or tabs have no holes.

[0054] Figure 7Four embodiments of the rectangular strips 44a, 44b, 44c, and 44d are shown. In each embodiment, the strip has a hollow area, which reduces the contact area of ​​the sheet, lowers the total weight of the elastic deformation member, and allows for adjustment of the stiffness of the elastic deformation member in various directions as needed.

[0055] Strip 44a includes a generally rectangular central hollow region and two portions 46 connecting the apex corners of the rectangle. Strip 44b includes two portions 48 connecting the long sides of the rectangle. These two portions 48 are generally perpendicular to the long sides. These two portions 48 may also be inclined, as shown in strip 44c, and are not necessarily parallel to each other. Strip 44d includes an elliptical central hollow region 50. The hollow region may also be any other shape (circle, rectangle, trapezoid, etc.).

Claims

1. A seal for an aircraft turbine engine comprising a plurality of sealing segments (20) circumferentially distributed around a longitudinal axis (X), each sealing segment (20) comprising a radially inner annular wall segment (22) and a radially outer annular wall segment (24) interconnected by an elastically deformable member (26), wherein each radially inner annular wall segment (22) is connected to an inner radial leg (28) and each radially outer annular wall segment (24) is connected to an outer radial leg (24), the inner leg (28) and the outer leg (30) being interconnected by the elastically deformable member (26), the elastically deformable member being composed of a stack of a plurality of adjacent elastic strips (32).

2. The seal according to the preceding claim, characterized in that, At least one of the inner radial support leg (28) and the outer support leg (30) includes a slot (34), the circumferential end of each strip (32) is longitudinally engaged with the slot, and the strip (32) is radially held within the slot (34).

3. The seal according to the preceding claim, characterized in that, Each of the inner radial support leg (28) and the outer radial support leg (30) includes a slot (34), the circumferential end of each strip (32) being longitudinally engaged with the slot, the strip (32) being radially held within the slot (34).

4. The seal according to claim 1 or 2, characterized in that, The inner radial support leg (28) of the sealing section includes a circumferentially through hollow region (36), the circumferential end of each strip (32) is engaged in the hollow region, and the locking member (38) passes through the thickness of the strip (32) to secure the strip (32) to the radially inner annular wall section (22).

5. The seal according to the preceding claim, characterized in that, The circumferential dimension of the strip (32) is greater than the thickness dimension and the longitudinal dimension of the strip (32), so that the strip (32) exhibits mechanical deformation characteristics similar to those of a beam.

6. The seal according to any one of the preceding claims, characterized in that, The strips (32) are fixed to each other at their circumferential ends and to the inner leg (28) and the outer leg (30).

7. The seal according to any one of the preceding claims, characterized in that, It comprises 2 to 40 stacked strips (32), preferably 2 to 30.

8. The seal according to any one of the preceding claims, characterized in that, Each strip (32) has a thickness between 0.05 and 5 mm and a longitudinal width between 5 and 50 mm.

9. The seal according to any one of the preceding claims, characterized in that, The strip (32) is made of metal and is welded to the radial leg at its circumferential end.

10. The seal according to any one of the preceding claims, characterized in that, The radially outer annular wall segment (24) constitutes a single annular wall, and the radially inner annular wall segment (22) is arranged circumferentially end to end.

11. A turbine for a turbine engine, for example for an aircraft, the turbine comprising a rotor and a casing, a guide (10) mounted in the casing, the guide (10) carrying a seal according to any one of the preceding claims, and the rotor comprising a cylindrical shroud (11) rotatable about a longitudinal axis (X), the cylindrical shroud (11) being arranged radially below the guide (10).

12. A turbine engine (1) comprising a seal according to any one of claims 1 to 10 or a turbine according to the preceding claim.

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