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

Abstract

The invention relates to a protective element (45.1, 45.2) for a compressor drum (20), the protective element being intended to be arranged at least partially between a blade root (25) and the compressor drum (20), the protective element 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 bearing surface portion (55.1, 55.2) for covering a blade root bearing 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 protective element for a low-pressure compressor drum of a turbomachine. The invention finds particularly advantageous application in the repair of worn low-pressure compressor drums. However, the invention can also be implemented with low-pressure compressor drums in a new condition at the end of production. Background Art

[0002] The turbofan works by compressing the air entering the engine. Most of this air forms a secondary flow, while the remaining portion forms a primary flow. This primary flow passes through a low-pressure compressor (integrated with the fan), a high-pressure compressor, a combustion chamber, a high-pressure turbine, and finally a low-pressure turbine before being ejected.

[0003] Fan compression occurs in two stages. In the first stage, a moving blade assembly provides acceleration to the air particles by deflecting them relative to the engine axis. This moving blade assembly consists of multiple blades mounted on a cylindrical hub called a fan disk, which is rotated by the low-pressure turbine.

[0004] In the second stage, a fixed fan assembly decelerates the air particles and converts part of their velocity into pressure. This fixed fan assembly is called an OGV ("Outlet Guide Vane") or "rectifier" 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. This compressor consists of moving blades mounted on a cylindrical section called the compressor drum, and a rectifier consisting of fixed blades. Depending on the turbine, the low-pressure compressor may have three to five stages, each consisting of a wheel with moving blades and a grid of corresponding rectifiers.

[0006] like Figure 1 As shown, for each stage of the low-pressure compressor, the moving blades 1 are installed in the corresponding cells 2 in the compressor drum 4 through the introduction windows 3 according to the following steps:

[0007] i—Insertion of the first blade 1 into the unit 2 through the introduction window 3 along the arrow F1 .

[0008] ii - Once the blade 1 is inserted, it is displaced tangentially along the arrow F2 by sliding it into the unit 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 repeated until all blades 1 are mounted in cells 2.

[0010] When the turbine and therefore the compressor drum 4 rotates, the moving blades 1 are radially held by the bearing areas 5 in the unit 2, as Figure 2 The installation process for installing the moving blades 1 into the unit 2 in the compressor drum 4 is a conventional and proven installation in the prior art.

[0011] However, at the level of the contact surface between the bearing area 6 of the blade root 7 and the bearing area 5 in the unit 2 , small displacements of the blade 1 within the unit 2 may locally wear said bearing area 5 in the unit 2 .

[0012] Depend on Figure 2 This wear, indicated by the dashed lines in the figure, can reduce the radial clearance above the moving blades 1, creating the risk of uncontrolled penetration of the moving blades 1 into the wear washers. This wear also risks causing axial displacement of the moving blades 1, potentially interfering with the stationary blades. Furthermore, positional differences between the moving blades 1 affect the balance of the compressor drum 4.

[0013] The installation of the moving blade 1 on a worn compressor drum 4 may also be hampered by the risk that the moving blade 1 is located between the unworn and worn parts of the bearing area 5 of the compressor drum 4 .

[0014] Significant wear may also affect the mechanical strength of the low-pressure compressor drum 4 , which may cause the compressor drum 4 to break during operation. Summary of the Invention

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

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

[0017] a connecting wall for covering an outer surface of the compressor drum, and

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

[0019] The invention thus allows to restore the contact interface between the bearing area in the drum unit and the moving blades.The invention thus allows to install the moving blades in the compressor drum in the same position as they were installed on a new drum at the end of production.

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

[0021] According to an embodiment of the invention, the protection element comprises a recess arranged opposite a portion of a blade introduction window in the compressor drum.

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

[0023] According to one embodiment of the invention, the connecting wall comprises at least one passage opening for a protruding part of the passage region of the gasket.

[0024] According to one embodiment of the invention, the protective element consists of a folded metal sheet having a thickness between 0.2 mm and 0.4 mm.

[0025] According to one embodiment of the present invention, the protection element is made of nickel-based metal material.

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

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

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

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

[0030] - Two mounting grooves machined upstream and downstream of the unit, and

[0031] - Mounting an upstream protection element and a downstream protection element such that the protection elements cooperate with corresponding mounting grooves in the compressor drum and cover upstream and downstream bearing areas in the unit, respectively.

[0032] According to one embodiment of the invention, the method further comprises the step of machining the channel area for the gasket to have alternating protruding portions and flat portions in order to facilitate mounting of the protection element on the compressor drum.

[0033] According to one embodiment of the invention, each protection element is mounted by applying a radial force to the protection element so that the connecting wall of the protection element deforms so as to allow the protruding portion of each protection element to cooperate with the corresponding mounting groove before returning to its initial flat shape so as to cover the corresponding outer face of the compressor drum.

[0034] According to one embodiment of the invention, the method further comprises the step of machining the outer face of the compressor drum upstream and downstream of the unit, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention will be better understood and other characteristics and advantages will become apparent on reading the following detailed description, including examples given for illustrative purposes with reference to the accompanying drawings, which are presented by way of non-limiting examples and which may serve to provide a thorough understanding of the invention and the description of its embodiments and ultimately contribute to its definition, in which:

[0036] [ Figure 1 ] has been described Figure 1 is a perspective view inside the unit showing the installation of blades into the low-pressure compressor drum;

[0037] [ Figure 2 ] has been described Figure 2 is a cross-sectional view of a compressor drum unit showing wear in the bearing area caused by the blade roots;

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

[0039] [ Figure 4 ] Figure 4 is a perspective view of a low-pressure compressor drum implementing the repair method of the present invention;

[0040] [ Figure 5 ] Figure 5 is a cross-sectional view of a unit in a low-pressure compressor drum in which the repair method of the present invention is 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 invention;

[0042] [ Figure 6b ] Figure 6b yes Figure 6a A detailed perspective view of the unit in FIG. 1 showing the machining process of the groove for receiving the gasket;

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

[0047] [ Figure 9 ] Figure 9 shows the different steps of installing the protection element according to the invention into a unit in a low-pressure compressor drum;

[0048] [ Figure 10 ] Figure 10 is a perspective view of a unit in which a protective element according to the invention has been installed in a low-pressure compressor drum;

[0049] [ Figure 11 ] Figure 11 is a perspective view showing the installation of blades into a unit in a low-pressure compressor drum on which a protection element according to the invention has been installed.

[0050] [ Figure 12 ] Figure 12 is a perspective view showing the positioning of upstream and downstream protection elements according to the invention between the support areas of the blades and the support area of ​​the unit in the low-pressure compressor drum.

[0051] It should be noted that in Figures 3 to 12 In the drawings, the structural and / or functional elements common to different embodiments have the same reference numerals. Therefore, unless otherwise specified, these elements have the same structure, size and material properties. DETAILED DESCRIPTION

[0052] In the remainder of the description, the terms "inner" and "outer" are to be understood with reference to the radial direction relative to the axis X1 of the compressor drum, that is, the "inner" face is the radially inner face and the "outer" face is the radially outer face, such that the inner face is closer to the axis X1 of the drum than the outer face.

[0053] Figure 3The front portion of a turbine 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, known as a "fan disk", which is driven in rotation by the low-pressure turbine.

[0054] The fixed blade assembly 15, located downstream of the movable blade assembly 12, decelerates the air particles and converts part of their velocity into pressure. This fixed blade assembly 15 is called an OGV ("outlet guide vane") or "rectifier" because it returns the air flow accelerated by the movable blade assembly 12 along the axis of the engine.

[0055] The low-pressure compressor 18 comprises moving blades 19 mounted on a cylindrical portion, known as the low-pressure compressor drum 20, and a rectifier 21 consisting of fixed blades. Depending on the configuration of the turbomachine 10, the low-pressure compressor 18 may comprise three to five stages, each consisting of a wheel with moving blades 19 and a corresponding grid of rectifiers 21.

[0056] 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.

[0057] like Figure 5 As shown, the unit 24 is delimited by an upstream blade root support area 26.1, an upstream inner circular portion 27.1, a unit bottom 28, a downstream inner circular portion 27.2, and a downstream blade root support area 26.2, against which the blade root support area 25 of corresponding shape abuts, and against which the 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 unit bottom 28, so that the unit 24 generally has a trapezoidal shape that is complementary to the shape of the blade root 25. This allows the blades 19 to be radially retained as the compressor drum 20 rotates.

[0058] The upstream outer circular portion 29 . 1 and the downstream outer circular portion 29 . 2 are located in the extension of the upstream blade root support area 26 . 1 and the downstream blade root support area 26 . 2 , respectively, in the corresponding unit 24 .

[0059] The compressor drum 20 further 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 oriented axially relative to the axis X1. The outer faces 30.1, 30.2 are located radially outwards from the compressor drum 20 relative to the axis X1.

[0060] The upstream vertical face 31.1 and the downstream vertical face 31.2 each extend in a radial plane relative to the axis X1 of the compressor drum 20. Each vertical face (upstream 31.1 and downstream 31.2) is located on the side opposite to the corresponding face comprising the outer circular portion (upstream 29.1 and downstream 29.2), the blade root support area (upstream 26.1 and downstream 26.2) and the inner circular portion (upstream 27.1 and downstream 27.2).

[0061] 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 unit 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 unit 24.

[0062] like Figure 6a and Figure 6b As shown, the compressor drum 20 further comprises an introduction window 36 for the blade roots 25 and two introduction windows 37 for the blade locks on either side of the introduction window 36 for the blade roots 25 .

[0063] Furthermore, a passage area 40 for the gasket is defined by two circumferential lower 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 unit 24. However, depending on the stage of the low-pressure compressor 18, the gasket can be installed upstream or downstream of the unit 24.

[0064] A method of repairing a worn low pressure compressor 20 drum is described below.

[0065] The step of machining the drum 20 is performed in order to eliminate wear on the bearing areas 26.1, 26.2 of the compressor drum 20 so as to define a unit 24 having an upstream bearing area 26.1 and a downstream bearing area 26.2 with a regular surface. The machining process is preferably performed so that the unit 24 has an axisymmetric configuration, without including blade or lock introduction windows 36, 34.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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 12 shown.

[0070] 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 .

[0071] according to Figure 7a and Figure 12 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] Similarly, according to Figure 7b and Figure 12 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] according to Figure 8aIn the illustrated locking geometry, the upstream protection element 45.1 includes an upstream recess 63.1 that is arranged opposite an upstream portion of the blade lock introduction window 36 in the low-pressure compressor drum 20. The upstream recess 63.1 is formed in the upstream outer portion 56.1 of the upstream protection element 45.1 and the upstream connecting wall 53.1. The upstream protection element 45.1 also includes recesses 64.1, each of which is arranged opposite a portion of the blade lock introduction window 37.

[0080] Similarly, according to Figure 8b 2. The downstream protection element 45.2 includes a downstream recess 63.2 that is arranged opposite a downstream portion of the blade lock introduction window 36 in the compressor drum 20. The downstream recess 63.2 is formed in the downstream outer portion 56.2 of the downstream protection element 45.2 and in the downstream connecting wall 53.2. The downstream protection element 45.2 also includes a recess 64.2 that is arranged opposite a portion of the blade lock introduction window 37.

[0081] Preferably, each protective element 45.1, 45.2 consists of a folded metal sheet having a thickness between 0.2 mm and 0.4 mm. The thickness of the metal sheet can be adapted to the maintenance requirements in order to compensate for the degree of wear of the unit 24. The thin metal sheet is sufficiently deformable to allow the protective elements 45.1, 45.2 to be adapted to the shape of the machining unit 24.

[0082] 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 wear resistance to titanium and allows the production of parts with low thickness that are rigid enough to withstand the grinding stresses at the interface between the moving blades 19 and the compressor drum 20.

[0083] The bearing area portions 55.1, 55.2 can be covered with a layer of lubricating varnish. This allows improving the contact conditions between the moving blades 19 and the corresponding bearing areas 26.1, 26.2 of the unit 24, in order to maximize the service life of the compressor drum 20.

[0084] Preferably, the tangential dimensions of the protective elements 45.1, 45.2 are such that a plurality (in particular 1 to 5) of movable blades 19 can come into contact with the latter. Advantageously, the tangential length of the protective elements 45.1, 45.2 is greater than the blade platform 65 (see Figure 11 ) in order to prevent the support area of ​​the blade 19 from coming into contact with two adjacent protective elements 45 . 1 , 45 . 2 , thereby creating a contact interruption between the moving blade 19 and the compressor drum 20 .

[0085] Furthermore, the tangential length of the protection elements 45.1, 45.2 is less than or equal to the tangential length of the five blade platforms 65, in order to allow deformation of the protection elements 45.1, 45.2 in order to mount them on the compressor drum 20. In fact, a greater length of the protection elements 45.1, 45.2 will increase their rigidity, which will prevent their deformation, which is necessary for mounting them on the compressor drum 20.

[0086] Refer to the following Figure 9 The following describes the steps for installing the protection element 45.1. These steps are identical to those for the protection element 45.2, except for the installation direction.

[0087] As shown in the left side view, the protection element 45.1 is positioned according to arrow F1 such that the inner portion 54.1 and the support area portion 55.1 are opposite the inner circular portion 27.1 and the support area 26.1 of the unit 24, respectively. The connecting wall 53.1 has a flat shape before its installation.

[0088] As shown in the middle view, a radial force is applied to the protective element 45.1 causing the connecting wall 53.1 to deform to allow the protruding portion 57.1 of the protective element 45.1 to cooperate with the mounting groove 46.1.

[0089] As shown in the right side view, the connecting wall 53.1 then resumes its original flat shape so as to cover the outer face 30.1 of the compressor drum 20. Thus, the upstream 45.1 or downstream 45.2 protection element remains around the upstream 35.1 or downstream 35.2 wall of the unit 24, respectively.

[0090] like Figure 10 As shown, a plurality of upstream protection elements 45.1 are thus arranged edge to edge so as to follow the circumference of the upstream wall 35.1 of the drum unit 24. Similarly, a plurality of downstream protection elements 45.2 are arranged edge to edge so as to follow the circumference of the downstream wall 35.2 of the drum unit 24. The geometry (standard or locking) of the protection elements 45.1, 45.2 is adapted to the configuration of the unit 24 in the region in which the protection elements 45.1, 45.2 are implanted.

[0091] like Figure 11 As shown, according to the previous reference Figure 1 As described, the blade 19 can be installed in the unit 24 by introducing the window 36. The blade lock is then implemented through the window 37 to prevent the blade 19 from moving in the unit 24.

[0092] The invention also relates to the assembly formed by the protective elements 45 . 1 , 45 . 2 and the compressor drum 20 .

[0093] Of course, different features, variants and / or embodiments of the present invention can be combined with one another in various combinations, as long as they do not contradict or exclude one another.

[0094] In addition, the present invention is not limited to the above-described embodiments, but is provided only as an example. The present invention includes various modifications, alternative forms and other variations that can be conceived by those skilled in the art in the context of the present invention, and in particular, any combination of the above-described various operating modes can be adopted 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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