Protective element for a compressor drum and method for repairing a compressor drum

Abstract

The invention relates to a protection element (45.1, 45.2) for a compressor drum (20) intended to be arranged at least partially between a blade root (25) and the compressor drum (20), comprising a first side wall (51.1, 51.2) comprising an inner portion (54.1, 54.2) for covering an inner circular portion of a pocket (24), a support surface portion (55.1, 55.2) for covering a blade root support surface of the pocket (24), and an outer portion (56.1, 56.2) for covering an outer circular portion of the compressor drum (20), a connecting wall (53.1, 53.2) for covering an outer face of the compressor drum (20), and a second side wall (52.1, 52.2) comprising a protruding portion (57.1, 57.2) for engaging with a mounting groove (46.1, 46.2) formed in a vertical face of the compressor drum (20).

Description

TECHNICAL FIELD

[0001] The present invention relates to a protection element for a low-pressure compressor drum of a turbomachine. The invention finds a particularly advantageous application for the repair of worn low-pressure compressor drums. However, the invention can also be implemented at the end of production with new low-pressure compressor drums. BACKGROUND

[0002] The turbomachine fan works by compressing the air that enters the engine. Most of this air constitutes the secondary flow, while another part constitutes the primary flow. This primary flow passes through a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and finally a low-pressure turbine integral with the fan, before being injected.

[0003] Fan compression takes place in two stages. In the first stage, the moving blade assembly provides acceleration to the air particles by deflecting them relative to the engine axis. This moving blade assembly comprises a plurality of blades mounted on a cylindrical hub called "fan disc" which is driven in rotation by the low-pressure turbine.

[0004] In the second stage, the fixed fan assembly decelerates the air particles and converts part of their speed into pressure. This fixed fan assembly is called OGV ("outlet guide vane") or "diffuser" because it returns the air flow accelerated by the moving fan assembly along the axis of the engine.

[0005] The same principle applies to the low-pressure compressor downstream of the fan. The low-pressure compressor comprises moving blades mounted on a cylindrical part called the compressor drum and a diffuser consisting of fixed blades. Depending on the turbomachine, the low-pressure compressor can have 3 to 5 stages, the compressor stage consisting of a wheel with moving blades and a corresponding grid of diffusers.

[0006] As shown in Figure 1 for each stage of this low-pressure compressor, the moving blades 1 are mounted in the corresponding cell 2 in the compressor drum 4 by introducing the window 3 according to the following steps:

[0007] i - the first blade 1 is inserted in the cell 2 along the arrow Fl by introducing the window 3.

[0008] ii - once the blade 1 is inserted, it is displaced tangentially along the arrow F2 by sliding it into the cell 2 so as to clear the introduction window 3. The first blade 1 is then mounted.

[0009] iii - the next blade can then be inserted and the operation is repeated until all the blades 1 are mounted within the cell 2.

[0010] When the turbine, and thus the compressor drum 4, rotates, the moving blades 1 are held radially by the support area 5 in the cell 2, as shown in Figure 2 The mounting process for mounting the moving blades 1 inside the cell 2 in the compressor drum 4 is a conventional and proven mounting of the prior art.

[0011] However, at the location of the contact surface between the support area 6 of the blade root 7 and the support area 5 in the cell 2, a slight displacement of the blade 1 inside the cell 2 can locally wear said support area 5 in the cell 2.

[0012] This wear, represented by the dotted line in Figure 2 , can reduce the radial clearance above the moving blades 1, which creates the risk that the moving blades 1 penetrate uncontrollably into the wear pads. This wear also presents the risk of an axial offset of the moving blades 1 that can interfere with the stationary blades. Furthermore, the positional differences between the moving blades 1 affect the balance of the compressor drum 4.

[0013] As there is a risk that the moving blades 1 are located between the non-worn and the worn part of the support area 5 of the compressor drum 4, it is also possible to affect the mounting of the moving blades 1 on the worn compressor drum 4.

[0014] Significant wear can also affect the mechanical strength of the low-pressure compressor drum 4, which makes it possible for the compressor drum 4 to break during operation. SUMMARY

[0015] The object of the present invention is to remedy the aforementioned drawbacks effectively by proposing a protection element for a compressor drum, said protection element being arranged at least partially between the blade root and said compressor drum, said protection element comprising:

[0016] a first side wall comprising an inner portion for covering the inner circular portion of the cell in said compressor drum, a support area portion for covering the blade root support area in said cell, and an outer portion for covering the outer circular portion of said compressor drum,

[0017] a connecting wall for covering the outer face of said compressor drum, and

[0018] a second side wall comprising a protruding portion for cooperating with a mounting groove in the vertical face of said compressor drum.

[0019] The present invention thus allows the contact interface between the support area in the drum cell and the moving blades to be restored. The present invention thus allows the moving blades to be mounted in the compressor drum in the same position as when they are mounted on a new drum at the end of production.

[0020] According to one embodiment of the application, the connecting wall is elastically deformable so as to allow mounting of the protective element on the compressor drum.

[0021] According to one embodiment of the application, the protective element comprises notches arranged opposite a portion of a blade introduction window in the compressor drum.

[0022] According to one embodiment of the application, the protective element comprises at least one notch arranged opposite a portion of a blade lock introduction window.

[0023] According to one embodiment of the application, the connecting wall comprises at least one passage opening of a projection of a passage area for a gasket.

[0024] According to one embodiment of the application, the protective element is made of folded sheet metal with a thickness of between 0.2 mm and 0.4 mm.

[0025] According to one embodiment of the application, the protective element is made of a nickel-based metal material.

[0026] According to one embodiment of the application, the bearing area portion is covered with a lubricating varnish layer.

[0027] According to one embodiment of the application, the tangential length of the protective element is greater than the tangential length of a blade platform and less than or equal to the tangential length of five blade platforms.

[0028] The application also relates to a method for repairing a compressor drum, the method comprising the following steps:

[0029] - machining to remove a bearing area wear in the compressor drum so as to define a cell having upstream and downstream bearing areas with regular surfaces,

[0030] - machining two mounting grooves upstream and downstream of the cell, respectively, and

[0031] - mounting an upstream protective element and a downstream protective element so that the protective elements respectively cooperate with corresponding mounting grooves in the compressor drum and cover the upstream and downstream bearing areas in the cell.

[0032] According to one embodiment of the application, the method further comprises the step of machining a passage area for a gasket to have alternating projections and flat portions so as to facilitate mounting of the protective element on the compressor drum.

[0033] According to an embodiment of the application, each protection element is mounted by applying a radial force to said protection element, so that the connecting wall of said protection element deforms in order to allow the protruding portion of each protection element to cooperate with the corresponding mounting recess in order to cover the corresponding external face of the compressor drum, before returning to its initial flat shape.

[0034] According to an embodiment of the application, the method further comprises the step of machining the external face of the compressor drum upstream and downstream of the unit, respectively. BRIEF DESCRIPTION OF DRAWINGS

[0035] The application will be better understood and other features and advantages will become apparent by reading the following detailed description, which includes reference to the attached drawings, presented for illustrative purposes only, which can be used in conjunction with the description to thoroughly understand the application and its embodiments, and finally to contribute to its definition, in which:

[0036] [ Figure 1 ] already described Figure 1 is a perspective view representing a unit for mounting a blade into a low-pressure compressor drum;

[0037] [ Figure 2 ] already described Figure 2 is a sectional view of a compressor drum unit, showing the wear of the bearing area caused by the blade root;

[0038] [ Figure 3 ] Figure 3 is a longitudinal sectional view of the turbine front;

[0039] [ Figure 4 ] Figure 4 is a perspective view of a low-pressure compressor drum on which a repair method according to the application has been implemented;

[0040] [ Figure 5 ] Figure 5 is a sectional view of a unit in a low-pressure compressor drum on which a repair method according to the application has been implemented;

[0041] [ Figure 6a ] Figure 6a is a partial perspective view of a unit in a compressor drum after the machining step of the repair method according to the application;

[0042] [ Figure 6b ] Figure 6b is Figure 6a a detailed perspective view of a unit in

[0043] [ Figure 7a ] Figure 7ais a perspective view of an upstream protection element for a compressor drum according to the present application, having a standard configuration;

[0044] [ Figure 7b ] Figure 7b is a perspective view of a downstream protection element for a compressor drum according to the present application, having a standard configuration;

[0045] [ Figure 8a ] Figure 8a is a perspective view of an upstream protection element for a compressor drum according to the present application, having a "locked" configuration;

[0046] [ Figure 8b ] Figure 8b is a perspective view of a downstream protection element for a compressor drum according to the present application, having a "locked" configuration;

[0047] [ Figure 9 ] Figure 9 different steps of installation of the protection element according to the present application into a cell in a low-pressure compressor drum are shown;

[0048] [ Figure 10 ] Figure 10 is a perspective view of a cell in a low-pressure compressor drum in which the protection element according to the present application has been installed;

[0049] [ Figure 11 ] Figure 11 is a perspective view showing the positioning of the upstream and downstream protection elements according to the present application between the support area of the blade and the support area of the cell in a low-pressure compressor drum.

[0050] It should be noted that, in the Figures 3 to 11 drawings, the structural and / or functional elements common to the different embodiments have the same reference numerals. Therefore, unless otherwise specified, these elements have the same structural, dimensional and material characteristics. DETAILED DESCRIPTION

[0051] In the remainder of the description, the terms "internal" and "external" should be understood with reference to the radial direction with respect to the axis X1 of the compressor drum, that is to say that the "internal" face is a radially internal face, while the "external" face is a radially external face, so that the internal face is closer to the axis X1 of the drum than the external face.

[0052] Figure 3A front of the turbomachine 10 is shown, comprising a fan 11 provided with a movable blade assembly 12 for accelerating air particles by deflecting them relative to the axis of the engine. The movable blade assembly 12 comprises a plurality of blades 13 mounted on a cylindrical hub 14, called "fan disk", which is driven in rotation by the low-pressure turbine.

[0053] A fixed blade assembly 15, downstream of the movable blade assembly 12, decelerates the air particles and converts part of their speed into pressure. This fixed blade assembly 15 is called OGV ("outlet guide vane") or "diffuser" because it returns the flow of air accelerated by the movable blade assembly 12 along the axis of the engine.

[0054] The low-pressure compressor 18 comprises mobile blades 19 mounted on a cylindrical portion called low-pressure compressor drum 20 and a diffuser 21 consisting of fixed blades. Depending on the configuration of the turbomachine 10, the low-pressure compressor 18 can comprise 3 to 5 stages, the compressor stages consisting of a wheel with mobile blades 19 and a corresponding grid of diffusers 21.

[0055] Figure 4 The compressor drum 20 shown, having an axis X1, has a cylindrical shape. The compressor drum 20 comprises a plurality of cells 24 corresponding to the number of stages of the low-pressure compressor 18. Each cell 24 is a circumferential groove extending along the circumference of the drum 20 and receiving a blade root 25, so that the blades 19 are angularly and regularly spaced along the circumference of the compressor drum 20. The compressor drum 20 comprises a fixed interface 22 with the hub 14 of the fan.

[0056] As Figure 5 shown, the cell 24 is delimited by an upstream blade root support area 26.1 against which a blade root support area 25 of corresponding shape abuts, an upstream inner circular portion 27.1, a cell bottom 28, a downstream inner circular portion 27.2 and a downstream blade root support area 26.2 against which a downstream blade root support area 26.2 of corresponding shape abuts. In cross-section, the upstream blade root surface 26.1 and the downstream blade root surface 26.2 form a non-zero angle with respect to the cell bottom 28, so that the cell 24 generally has a trapezoidal shape complementary to the shape of the blade root 25. This allows the blade 19 to be radially retained while the compressor drum 20 rotates.

[0057] An upstream outer circular portion 29.1 and a downstream outer circular portion 29.2 are respectively located in the extension of the upstream blade root support area 26.1 and the downstream blade root support area 26.2 in the corresponding cell 24.

[0058] The compressor wheel 20 also comprises an upstream outer face 30.1 and a downstream outer face 30.2. The outer faces 30.1, 30.2 have an annular shape axially oriented with respect to the axis X1. The outer faces 30.1, 30.2 are positioned radially outwardly from the compressor wheel 20 with respect to the axis X1.

[0059] The upstream vertical face 31.1 and the downstream vertical face 31.2 each extend in a radial plane with respect to the axis X1 of the compressor wheel 20. Each (upstream 31.1 and downstream 31.2) vertical face is located on an opposite side to the respective face comprising the (upstream 29.1 and downstream 29.2) outer circular portion, the (upstream 26.1 and downstream 26.2) blade root support area and the (upstream 27.1 and downstream 27.2) inner circular portion.

[0060] The upstream vertical face 31.1, the upstream outer face 30.1, the upstream outer circular portion 29.1, the upstream blade root support area 26.1 and the upstream inner circular portion 27.1 are formed in the upstream wall 35.1 of the cell 24. The downstream vertical face 31.2, the downstream outer face 30.2, the downstream outer circular portion 29.2, the downstream blade root support area 26.2 and the downstream inner circular portion 27.2 are formed in the downstream wall 35.2 of the cell 24.

[0061] As shown in Figs. 1 and 2, the compressor wheel 20 also comprises an upstream blade root 25.1 and a downstream blade root 25.2. The upstream blade root 25.1 and the downstream blade root 25.2 are each formed in the upstream wall 35.1 and in the downstream wall 35.2 of the cell 24. Figure 6a and Figure 6b As shown in Figs. 1 and 2, the compressor wheel 20 also comprises an upstream blade root 25.1 and a downstream blade root 25.2. The upstream blade root 25.1 and the downstream blade root 25.2 are each formed in the upstream wall 35.1 and in the downstream wall 35.2 of the cell 24.

[0062] Furthermore, a passage area 40 for a gasket is defined by two circumferential low walls 41 from the outer face 30.1, between which a groove 42 for receiving a gasket (not shown) extends. In the example shown, the gasket is intended to be arranged upstream of the cell 24. However, depending on the stage of the low-pressure compressor 18, the gasket can be mounted upstream or downstream of the cell 24.

[0063] A method of repairing a worn low-pressure compressor 20 wheel is described below.

[0064] The steps of machining the wheel 20 are performed so as to eliminate the wear on the support areas 26.1, 26.2 of the compressor wheel 20 so as to define a cell 24 having upstream and downstream support areas 26.1, 26.2 with regular surfaces. The machining process is preferably performed so that the cell 24 has an axisymmetric configuration, not comprising blade or lock introduction windows 36, 34.

[0065] A step of machining the compressor drum 20 is also performed to allow installation of the protection elements 45.1, 45.2 described in more detail below. According to this operation, two mounting grooves 46.1, 46.2 are formed in the upstream and downstream vertical faces 31.1, 31.2, respectively upstream and downstream of the unit 24.

[0066] A further step is performed to machine the upstream outer face 30.1 and the downstream outer face 30.2 of the low-pressure compressor drum 20 in order to obtain a regular surface. In particular, the channel area 40 for the gasket is machined to form alternating protruding portions 48 and flat portions 49 to facilitate the mounting of the protective elements 45.1, 45.2 on the low-pressure compressor drum 20.

[0067] Once the machining step is completed, the upstream and downstream protection elements 45.1, 45.2 are mounted so that they cooperate with corresponding mounting grooves 46.1, 46.2 in the drum 20 and cover the upstream and downstream support areas 26.1, 26.2 in the unit 24, respectively.

[0068] Thus, the protective elements 45.1, 45.2 fill the gap between the bearing area of ​​the moving blades 19 and the bearing area of ​​the unit 24 in the compressor drum 20, as shown in FIG. Figure 11 shown.

[0069] More specifically, each protection element 45 . 1 , 45 . 2 (upstream or downstream) is intended to be arranged at least partially between the blade root 25 and the compressor drum 20 .

[0070] according to Figure 7a and Figure 11 Shown is a standard upstream geometry, the upstream protection element 45.1 (also called "upstream foil") comprising a first upstream side wall 51.1, a second upstream side wall 52.1 and an upstream connecting wall 53.1 providing a connection between the first upstream side wall 51.1 and the second upstream side wall 52.1.

[0071] The first upstream side wall 51.1 comprises an upstream inner portion 54.1 for covering the upstream inner circular portion 27.1 of the cell 24, an upstream support area portion 55.1 for covering the upstream blade root support area 26.1 in the cell 24, and an upstream outer portion 56.1 for covering the upstream outer circular portion 29.1 of the drum in extension of the upstream blade root support area 26.1. The upstream support area portion 55.1 forms a non-zero angle with respect to the upstream connecting wall 53.1.

[0072] The purpose of the upstream connecting wall 53.1 is to cover the upstream outer face 30.1 of the compressor drum 20. The upstream connecting wall 53.1 has a flat shape. The upstream connecting wall 53.1 is elastically deformable to allow the upstream protection element 45.1 to be mounted on the compressor drum 20. The upstream connecting wall 53 includes at least one passage opening 60 for the protruding portion 48 of the gasket passage area 40. The number of passage openings depends on the configuration of the gasket passage area 40 in which the upstream protection element 45.1 is located.

[0073] The second upstream sidewall 52.1 includes an upstream protrusion 57.1 for cooperating with the upstream mounting groove 46.1 in the upstream vertical face 31.1 of the drum. The upstream protrusion 57.1 extends toward the interior of the upstream protection element 45.1. The second upstream sidewall 52.1 has an S-shaped configuration. The upstream protection element 45.1 has an axisymmetric geometry at the unit 24.

[0074] Similarly, according to Figure 7b and Figure 11 In the standard downstream geometry shown, the downstream protection element 45.2 comprises a first downstream side wall 51.2, a second downstream side wall 52.2 and a downstream connecting wall 53.2 for connecting the first downstream side wall 51.2 and the second downstream side wall 52.2 to each other.

[0075] The first downstream side wall 51.2 comprises an inner downstream portion 54.2 for covering the inner circular downstream portion 27.2 of the unit 24, a downstream support area portion 55.2 for covering the downstream blade root support area 26.2 of the unit 24, and a downstream outer portion 56.2 for covering the downstream outer circular portion 29.2 of the drum 20 in extension of the downstream blade root support area 26.2. The downstream support area portion 55.2 forms a non-zero angle with respect to the downstream connecting wall 53.2.

[0076] The downstream connecting wall 53.2 is intended to cover the downstream outer face 30.2 of the compressor drum 20. The downstream connecting wall 53.2 has a flat shape. The downstream connecting wall 53.2 is elastically deformable for mounting the downstream protection element 45.2 on the compressor drum 20.

[0077] The second downstream sidewall 52.2 includes a downstream protrusion 57.2 for cooperating with the downstream mounting recess 46.2 in the downstream vertical face 31.2 of the drum 20. The downstream protrusion 57.2 extends toward the interior of the downstream protection element 45.2. The second downstream sidewall 52.2 has an S-shaped configuration. The downstream protection element 45.2 has an axisymmetric geometry at the unit 24.

[0078] according to Figure 8aThe upstream protection element 45.1 comprises, in the illustrated locking geometry, an upstream notch 63.1 arranged opposite an upstream portion of the blade entry window 36 in the low-pressure compressor drum 20. The upstream notch 63.1 is formed in the upstream outer portion 56.1 and the upstream connecting wall 53.1 of the upstream protection element 45.1. The upstream protection element 45.1 also comprises notches 64.1 each arranged opposite a portion of the blade lock entry window 37.

[0079] Similarly, according to the locking geometry illustrated, Figure 8b The downstream protection element 45.2 comprises, in the illustrated locking geometry, a downstream notch 63.2 arranged opposite a downstream portion of the blade entry window 36 in the compressor drum 20. The downstream notch 63.2 is formed in the downstream outer portion 56.2 and the downstream connecting wall 53.2 of the downstream protection element 45.2. The downstream protection element 45.2 also comprises notches 64.2 arranged opposite a portion of the blade lock entry window 37.

[0080] Preferably, each protection element 45.1, 45.2 is made of folded sheet metal with a thickness between 0.2 mm and 0.4 mm. The thickness of the sheet metal can be adapted to the repair requirements in order to compensate for the degree of wear of the unit 24. The thin sheet metal is sufficiently deformable in order to allow the protection element 45.1, 45.2 to match the shape of the machined unit 24.

[0081] Each protection element 45.1, 45.2 is made of a nickel-based metal material, in particular of the Inconel® type (registered trademark). This material offers superior resistance to wear than titanium and allows the production of parts with low thickness that are sufficiently rigid to withstand the matting stresses at the interface between the moving blade 19 and the compressor drum 20.

[0082] The support area portions 55.1, 55.2 can be covered with a layer of lubricating varnish. This allows the contact conditions between the moving blade 19 and the corresponding support area 26.1, 26.2 of the unit 24 to be improved in order to maximize the service life of the compressor drum 20.

[0083] Furthermore, the tangential length of the protection element 45.1, 45.2 is less than or equal to the tangential length of five blade platforms 65 in order to allow the protection element 45.1, 45.2 to be deformed in order to be mounted on the compressor drum 20. Indeed, a greater length of the protection element 45.1, 45.2 would increase its rigidity, which would prevent it from being deformed, which is necessary for its mounting on the compressor drum 20.

[0084] Reference is made below to Figure 9The various steps of installing the protective element 45.1 are described. These steps are identical to those of the protective element 45.2, except for the installation direction.

[0085] As shown in the left side view, the protective element 45.1 is positioned according to the arrow Fl so that the inner portion 54.1 and the bearing area portion 55.1 are opposite the inner circular portion 27.1 and the bearing area 26.1 of the cell 24, respectively. The connecting wall 53.1 has a flat shape before its installation.

[0086] As shown in the middle view, a radial force is applied to the protective element 45.1 so that the connecting wall 53.1 deforms to allow the protruding portion 57.1 of the protective element 45.1 to cooperate with the installation groove 46.1.

[0087] As shown in the right side view, the connecting wall 53.1 then resumes its initial flat shape so as to cover the outer face 30.1 of the compressor drum 20. Thus, the upstream protective element 45.1 or the downstream protective element 45.2 remains around the upstream wall 35.1 or the downstream wall 35.2 of the cell 24, respectively.

[0088] As shown in the left side view, the protective element 45.1 is positioned according to the arrow Fl so that the inner portion 54.1 and the bearing area portion 55.1 are opposite the inner circular portion 27.1 and the bearing area 26.1 of the cell 24, respectively. The connecting wall 53.1 has a flat shape before its installation. Figure 10 As shown, a plurality of upstream protective elements 45.1 are thus arranged edge-to-edge so as to follow the circumference of the upstream wall 35.1 of the cell 24 in the drum. Similarly, a plurality of downstream protective elements 45.2 are arranged edge-to-edge so as to follow the circumference of the downstream wall 35.2 of the cell 24 in the drum. The geometry (standard or locking) of the protective elements 45.1, 45.2 is adjusted according to the configuration of the cell 24 in the implantation area for the protective elements 45.1, 45.2.

[0089] The invention also relates to an assembly formed by the protective elements 45.1, 45.2 and the compressor drum 20.

[0090] Of course, the different features, variants and / or embodiments of the invention can be associated with each other in various combinations, as long as they are not contradictory or exclusive to each other.

[0091] Furthermore, the invention is not limited to the embodiments described above, but is provided by way of example only. The invention comprises various modifications, alternatives and other variants that can be envisaged by a person skilled in the art in the context of the invention, and in particular, any combination of the various operating modes described above can be taken individually or in combination.

Claims

1. A protective element (45.1, 45.2) for a compressor drum (20), the protective element being arranged at least partially between a blade root (25) and the compressor drum (20), wherein The protection element comprises: a first side wall (51.1, 51.2), the first side wall comprising an inner portion (54.1, 54.2) for covering an inner circular portion (27.1, 27.2) in a pocket (24) in the compressor drum (20), a support area portion (55.1, 55.2) for covering a blade root support area (26.1, 26.2) in the pocket (24), and an outer portion (56.1, 56.2) for covering an outer circular portion (29.1, 29.2) of the compressor drum (20), a connecting wall (53.1, 53.2) for covering the outer face (30.1, 30.2) of the compressor drum (20), and A second side wall (52.1, 52.2) comprising a protruding portion (57.1, 57.2) for cooperating with a mounting recess (46.1, 46.2) in a vertical face (31.1, 31.2) of the compressor drum (20).

2. The protection element according to claim 1, wherein: The connecting walls (53.1, 53.2) are elastically deformable to allow the protective element (45.1, 45.2) to be mounted on the compressor drum (20).

3. The protection element according to claim 1 or 2, wherein: The protection element comprises a recess (63.1, 63.2) arranged opposite a portion of a blade introduction window (36) in the compressor drum (20).

4. The protection element according to claim 1 or 2, wherein: The protective element comprises at least one notch (64.1, 64.2) arranged opposite a portion of the blade lock introduction window (37).

5. The protection element according to claim 1 or 2, wherein: The connecting wall (53.1, 53.2) comprises at least one passage opening (60) for a protruding part (48) of the passage region (40) of the gasket.

6. The protection element according to claim 1 or 2, wherein: The protective element consists of a folded metal sheet with a thickness between 0.2 mm and 0.4 mm.

7. The protection element according to claim 1 or 2, wherein: The protection element is made of nickel-based metal material.

8. The protection element according to claim 1 or 2, wherein: The bearing area portions (55.1, 55.2) are covered with a lubricating varnish layer.

9. The protection element according to claim 1 or 2, wherein: The tangential length of the protective element (45.1, 45.2) is greater than the tangential length of the blade platform (65) and is less than or equal to the tangential length of five blade platforms (65).

10. A method for repairing a compressor drum (20), wherein: The method comprises the following steps: machining to remove wear from bearing areas (26.1, 26.2) in the compressor drum (20) to define a pocket (24) having upstream and downstream bearing areas (26.1, 26.2) with regular surfaces, Two mounting grooves (46.1, 46.2) are machined upstream and downstream of the recess (24), respectively, and A protection element (45.1, 45.2) according to any one of claims 1 to 9, the protection elements (45.1, 45.2) being an upstream protection element (45.1) and a downstream protection element (45.2), is mounted such that the protection elements (45.1, 45.2) respectively cooperate with corresponding mounting recesses (46.1, 46.2) in the compressor drum (20) and cover upstream and downstream bearing areas (26.1, 26.2) in the recess (24).

11. The method according to claim 10, wherein: The method further comprises the step of machining a channel area (40) for a gasket to have alternating protruding portions (48) and flat portions (49) to facilitate mounting of a protective element (45.1, 45.2) on the compressor drum (20).

12. The method according to claim 10 or 11, wherein: Each protection element (45.1, 45.2) is installed by applying a radial force to the protection element (45.1, 45.2) so that the connecting wall (53.1, 53.2) of the protection element (45.1, 45.2) is deformed to allow the protruding portion (57.1, 57.2) of each protection element (45.1, 45.2) to cooperate with the corresponding mounting groove (46.1, 46.2) before the connecting wall (53.1, 53.2) returns to its original flat shape, thereby covering the corresponding outer face (30.1, 30.2) of the compressor drum (20).

13. The method according to claim 10 or 11, wherein: The method further comprises the step of machining the outer face (30.1, 30.2) of the compressor drum (20) upstream and downstream of the pocket (24), respectively.

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