Repair skin for a fan outlet guide vane platform and associated repair method

Abstract

The invention relates to an assembly for an aircraft engine, comprising: - a damaged guide platform (30) extending between two consecutive guide vanes (17), wherein the guide platform (30) has an off-flow face (31) intended to face a structural element (28) on a side opposite a flow path (14) and a flow face (32) forming at least a portion of the flow path (14), wherein the assembly further comprises a repair skin (33) bonded to the guide platform (30) so as to at least partly cover the flow face (32) of the guide platform (30) in order to ensure aerodynamic continuity of the flow path (14).

Description

DESCRIPTION TITLE: REPAIR SKIN FOR A BLOWER RECTIFIER PLATFORM AND ASSOCIATED REPAIR METHOD

[0001] The present invention relates to a repair skin for a fan stator platform and to the associated repair method. The invention finds a particularly advantageous, but not exclusive, application in the field of aeronautics, with dual-flow turbomachinery.

[0002] As is well known, a turbomachine consists of a fan casing surrounding a fan designed to compress the air entering the engine. Part of this air constitutes the primary flow, circulating in a primary flow channel, and the other part constitutes the secondary flow, circulating in a secondary flow channel. The primary flow passes through a low-pressure compressor, a high-pressure compressor, then a combustion chamber, a high-pressure turbine, and finally a low-pressure turbine before being ejected. The secondary flow bypasses the hot section of the turbomachine.

[0003] A straightener is positioned downstream of the fan in the secondary flow channel. The straightener comprises a plurality of fixed vanes that straighten the airflow exiting the fan. These vanes are also each designated by the acronym OGV, for "Outlet Guide Vane," according to Anglo-Saxon terminology. The straightener also includes arms that connect a hub of the straightener to a VCI (Variable Control Interface) ferrule located downstream of the fan casing.

[0004] Stator platforms, known as "OGV platforms," ​​extend between two consecutive blades to form a portion of the radially outer side of the secondary flow stream. These OGV platforms, generally made of a rigid plastic material, contribute to the aerodynamic performance of the secondary flow channel between the stator blades.

[0005] During flights, the engine is subjected to various weather conditions and ingestions, particularly of birds. This can lead to damage to engine input components, especially the OGV platforms.

[0006] Damage to one or more OGV platforms can lead to a decrease in engine performance that may last for several flight cycles before the damaged platforms are replaced.

[0007] The invention aims to effectively remedy this drawback by proposing an assembly for an aircraft engine comprising: - a damaged rectifier platform extending between two successive rectifier blades, said rectifier platform having an off-flow face intended to be turned towards a structural element on a side opposite a flow channel and a flow face forming at least a portion of a flow channel, - said assembly further comprising a repair skin glued onto the rectifier platform, so as to cover at least part of the flow face of said rectifier platform to ensure aerodynamic continuity of the flow vein.

[0008] The invention thus makes it possible, thanks to the repair skin, to reconstruct the flow path following damage to the straightener platform. Furthermore, the invention increases the number of flight cycles before replacing the broken part while minimizing the loss of aerodynamic performance. The invention also has the advantage of not interfering with the assembly of adjacent parts and is economically advantageous because it is inexpensive to implement.

[0009] According to one embodiment of the invention, the repair skin has a low thickness, in particular less than 5mm, and preferably less than 2mm.

[0010] According to one embodiment of the invention, the repair skin includes a chamfer made in at least one inlet edge of an airflow.

[0011] According to one embodiment of the invention, the rectifier platform includes fixing holes intended to receive fixing elements for fixing the rectifier platform onto the structural element.

[0012] According to one embodiment of the invention, the straightener platform comprises pads extending from the off-grain face, said pads carrying shock absorbers intended to bear against the structural element.

[0013] According to one embodiment of the invention, the straightener platform includes stiffening ribs.

[0014] The invention also relates to a method for repairing a damaged rectifier platform extending between two successive rectifier blades, said rectifier platform having an off-flow face intended to be turned towards a structural element on a side opposite a flow duct and a duct face forming at least a portion of a flow duct, said method comprising a step of bonding a repair skin onto the rectifier platform, so as to at least partially cover the duct face of said rectifier platform to ensure aerodynamic continuity of the flow duct.

[0015] According to one embodiment of the invention, said method includes a preliminary cutting step of an outer contour of the repair skin so as to correspond to the dimensions of the straightener platform.

[0016] According to one embodiment of the invention, the cutting of the outer contour of the repair skin is carried out using a template having dimensions corresponding to the outer contour of the platform.

[0017] According to one embodiment of the invention, the repair skin is pre-cut to the dimensions of the straightener platform.

[0018] Advantageously, the said process is implemented during an underwing inspection and repair phase of the aircraft.

[0019] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures, presented by way of non-limiting examples, which may serve to complete the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

[0020] [Fig. 1] Figure 1 is a partial longitudinal cross-sectional view of an aircraft turbomachine;

[0021] [Fig. 2] Figure 2 is a detailed perspective view illustrating the positioning of OGV platforms on an intermediate casing ferrule;

[0022] [Fig. 3] Figure 3 is a perspective view of an OGV platform intended to be covered by a repair skin;

[0023] [Fig. 4] Figure 4 is a perspective view of a rear face of an OGV platform intended to be covered by a repair skin;

[0024] [Fig. 5] Figure 5 is an exploded perspective view of a repair skin according to the invention intended to cover a radially internal face of an OGV platform;

[0025] [Fig. 6] Figure 6 is a perspective view showing the curvature of an OGV platform covered by a repair skin according to the invention;

[0026] [Fig. 7] Figure 7 is a schematic cross-sectional view of a repair skin according to the invention;

[0027] [Fig. 8] Figure 8 is a schematic representation of a set of repair skins taking the form of strips glued onto a common support.

[0028] It should be noted that, in the figures, structural and / or functional elements common to the different embodiments may have the same reference numbers. Thus, unless otherwise stated, such elements have identical structural, dimensional, and material properties.

[0029] In the following description, the radially internal and radially external faces of the straightener platform and the repair skin are considered with respect to the X-axis of the turbomachine.

[0030] Figure 1 shows a schematic partial longitudinal cross-sectional view of an aircraft turbomachine 10, here a turbofan engine with X-axis orientation. This turbomachine 10 comprises a fan casing 12 surrounding a fan 11 for compressing the air entering the engine. Part of this air constitutes the primary flow circulating in a primary flow channel 13, and the other part of this air constitutes the secondary flow circulating in a secondary flow channel 14. The primary flow passes through a low-pressure compressor 15, a high-pressure compressor, then a combustion chamber, a high-pressure turbine, and finally a low-pressure turbine before being ejected. The high-pressure compressor, combustion chamber, high-pressure turbine, and low-pressure turbine are not shown in the figure to facilitate understanding of the invention.

[0031] An 18 rectifier, also designated by the acronym OGV for "Outlet The "Guide Vane," according to Anglo-Saxon terminology, extends downstream of the blower 11 in the secondary flow channel 14. The straightener 18 comprises a plurality of fixed blades 17 for straightening the airflow exiting the blower 11. The straightener 18 also includes arms providing a mechanical connection between a hub 20 of the straightener 18 and an intermediate casing ferrule 28 (VCI) located downstream of the blower casing 12.

[0032] Rectifier platforms 30, visible in Figure 2, are fixed to a structural element, in this case the intermediate casing ferrule 28, which is generally annular in shape. Each rectifier platform 30 extends between two successive rectifier blades 17.

[0033] Each rectifier platform 30 has an off-flow face 31 corresponding to a radially external face of the rectifier platform 30. The off-flow face 31 is turned towards the structural element, in this case the intermediate housing shell 28, on a side opposite the secondary flow channel 14. Each rectifier platform 30 also has a flow face 32 corresponding to a radially internal face 32 of the rectifier platform 30. The flow face 32 forms at least a portion of the secondary flow channel 14. A rectifier platform 30 can extend along an angular sector of an annular shape. The vein face 32 of the rectifier platform 30 has a concave shape while the off-vein face 31 of the rectifier platform 30 has a convex shape, as illustrated in Figure 6. Alternatively, a rectifier platform 30 can extend along an angular sector of a frustoconical shape.In some cases, a rectifier platform 30 may also exhibit at least partially a planar shape.

[0034] As illustrated in Figures 3 and 4, the rectifier platform 30 has mounting holes 34 for receiving fasteners to fix the rectifier platform 30 to the intermediate housing ferrule 28. The fasteners preferably consist of screws, intended to be screwed onto the intermediate housing ferrule 28.

[0035] The rectifier platform 30 may include pads 40 extending from the non-vein face 31 (see Figure 4). The pads 40 carry dampers 41 intended to bear against the intermediate housing ferrule 28. The dampers 41 are made of an elastic material, such as an elastomer or silicone.

[0036] The straightener platform 30 may also include stiffening ribs 42 made on its off-rib face 31.

[0037] A repair skin 33 shown in Figures 3, 5 and 6 is bonded, without prior heating, onto a damaged rectifier platform 30, so as to cover at least part of the vein face 32 of said platform. straightener 30 to ensure aerodynamic continuity of the secondary flow channel 14.

[0038] For this purpose, the repair skin 33 has a radially internal face 35 with a smooth configuration and a radially external face 36 provided with an adhesive layer so that it can be glued to the vein face 32 of the straightener platform 30. The adhesive can be chosen from a neoprene glue, a cyanoacrylate glue, an epoxy glue or any other type of glue suitable for fixing a repair skin 33 to the straightener platform 30 generally made of a rigid plastic material.

[0039] The repair skin 33 has an outer contour corresponding to that of the blower straightener platform 30. The outer contour of the repair skin 33 may correspond exactly to the outer contour of the platform. In this case, the repair skin 33 completely covers the vein face 32 of the straightener platform 30 to recreate a complete external surface of the straightener platform 30. Alternatively, the repair skin 33 has an outer contour circumscribed within the contour of the straightener platform 30.

[0040] The repair skin 33 advantageously has a low thickness, in particular less than 5 mm, and preferably less than 2 mm. The repair skin 33 can be made of a material chosen from: a plastic material, a metallic material, or a composite material. The material chosen is sufficiently strong to withstand the impacts that may result from the ingestion of debris and / or volatiles inside the engine.

[0041] According to a particular embodiment shown in Figure 7, the repair skin 33 comprises an adhesive layer 33.1, an intermediate structural layer 33.2 made of a rigid material, in particular a plastic material, and an outer layer 33.3 made of a shear-thickening material, in particular a shear-thickening plastic material. The shear-thickening material has a mechanical behavior that depends on the speed of an impact (and therefore on the shear level) experienced by layer 33.3. When the impact speed is high, layer 33.3 exhibits a behavior rigid. In the case where the impact speed is low, layer 33.3 exhibits a flexible and deformable behavior.

[0042] In certain embodiments, the repair skin has a chamfer 39 formed in at least one inlet edge of an airflow. The inlet edge of the airflow is the edge of the repair skin 33 that the airflow encounters first when it flows inside the secondary flow channel 14. Such a configuration improves the aerodynamics of the repair skin 33.

[0043] The invention also relates to a method for repairing a damaged rectifier platform 30 comprising a step of bonding, without prior heating, a repair skin 33 onto the rectifier platform 30, so as to cover the vein face 32 of said rectifier platform 30 to ensure aerodynamic continuity of the secondary flow vein 14.

[0044] The process may include a preliminary cutting step of an outer contour of the repair skin 33 so as to correspond to the dimensions of the straightener platform 30. The outer contour of the repair skin 33 may correspond exactly to the outer contour of the straightener platform 30. Alternatively, the outer contour of the repair skin 33 may be circumscribed within the outer contour of the straightener platform 30.

[0045] The cutting of the outer contour of the repair skin 33 is carried out using a template having dimensions corresponding to the outer contour of the straightener platform 30.

[0046] Alternatively, the repair skin 33 is pre-cut to the dimensions of the straightener platform 30. In this case, the operator will only have to remove a protective film from the repair skin 33 before sticking it onto the vein face 32 of the straightener platform 30.

[0047] As illustrated in Figure 8, it is also possible to select the repair skin 33 from a set of pre-cut repair skins 33 covering a plurality of rectifier platform configurations 30 used in the turbomachine, typically between 20 and 40 different configurations. Indeed, depending on their positioning within the turbomachine, the rectifier platforms 30 have slightly different dimensions and shapes. All the repair skins 33, which are in the form of strips, are bonded to a common support 44. It is possible to detach the selected repair skin 33 from the common support 44 and then bond said repair skin 33 to the rectifier platform 30 corresponding to the configuration of the selected repair skin 33.

[0048] Alternatively, the repair skin 33 has dimensions corresponding only to the dimensions of the damaged area of ​​the rectifier platform 30.

[0049] Advantageously, the method according to the invention is implemented during an underwing inspection and repair phase of the aircraft. This underwing inspection and repair phase can take place between flights on the tarmac or within an airport facility. This inspection and repair phase is short (on the order of a few hours at most) in contrast to repair phases carried out in a maintenance hangar that can last several days.

[0050] In the embodiment shown in Figures 1 to 6, the straightener platforms 30 are arranged radially outside the secondary flow channel 14. If a straightener platform 30 is arranged radially inside the secondary flow channel 14, the off-channel face of the straightener platform 30 corresponds to a radially internal face, and the channel face of the straightener platform 30 corresponds to a radially external face of the straightener platform 30. A repair skin 33 can then be bonded to a radially external damaged channel face of the straightener platform 30.

[0051] Alternatively, the rectifier platform 30 can be fixed on a structural element other than the intermediate housing ferrule 28.

[0052] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways as long as they are not incompatible or mutually exclusive.

[0053] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variations that a person skilled in the art may envision within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be considered separately or in combination.

Claims

DEMANDS 1. Assembly for an aircraft engine comprising: - a damaged straightener platform (30) extending between two successive straightener blades (17), said straightener platform (30) having an off-flow face (31) intended to be turned towards a structural element (28) on a side opposite a flow duct (14) and a duct face (32) forming at least a portion of the flow duct (14), characterized in that said assembly further comprises a repair skin (33) bonded to the straightener platform (30), so as to cover at least part of the duct face (32) of said straightener platform (30) to ensure aerodynamic continuity of the flow duct (14).

2. Assembly according to claim 1, characterized in that the repair skin (33) has a low thickness, in particular less than 5mm, and preferably less than 2mm.

3. Assembly according to claim 1 or 2, characterized in that the repair skin (33) comprises an adhesive layer (33.1), an intermediate structural layer (33.2), and an outer layer (33.3) made of a shear-thickening material.

4. Assembly according to any one of claims 1 to 3, characterized in that the repair skin (33) has a chamfer (39) made in at least one inlet edge of an airflow.

5. Assembly according to any one of claims 1 to 4, characterized in that the rectifier platform (30) has fixing holes (34) intended to receive fixing elements for fixing the rectifier platform (30) onto the structural element (28).

6. Assembly according to any one of claims 1 to 5, characterized in that the rectifier platform (30) comprises pads (40) extending from the off-vein face (31), said studs (40) bearing shock absorbers (41) intended to support against the structural element (28).

7. Assembly according to any one of claims 1 to 6, characterized in that the straightener platform (30) comprises stiffening ribs (42).

8. Method for repairing a damaged stator platform (30) extending between two successive stator blades (17), said stator platform (30) having an off-flow face (31) intended to be turned towards a structural element (28) on a side opposite a flow duct (14) and a duct face (32) forming at least a portion of the flow duct (14), characterized in that said method comprises a step of bonding a repair skin (33) onto the stator platform (30), so as to at least partially cover the duct face (32) of said stator platform (30) to ensure aerodynamic continuity of the flow duct (14).

9. Method according to claim 8, characterized in that it comprises a preliminary cutting step of an outer contour of the repair skin (33) so as to correspond to dimensions of the straightener platform (30).

10. Method according to claim 9, characterized in that the cutting of the outer contour of the repair skin (33) is carried out by means of a template having dimensions corresponding to the outer contour of the platform.

11. Method according to claim 8, characterized in that the repair skin (33) is pre-cut to dimensions of the straightener platform (30).

12. A method according to claim 11, characterized in that it comprises a step of selecting the repair skin (33) from a set of pre-cut repair skins (33) covering a plurality of rectifier platform configurations (30) used in the turbomachine.

13. Method according to claim 12, characterized in that all the repair skins (33) in the form of strips are glued onto a common support (44), said method includes a step of peeling off the selected repair skin (33) and then gluing said repair skin (33) onto the straightener platform (30) corresponding to the configuration of the selected repair skin (33).

14. A method according to any one of claims 8 to 13, characterized in that it is implemented during an underwing inspection and repair phase of the aircraft.

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