Rigid panel with heat exchanger for propulsion assembly and associated manufacturing method

Abstract

The invention relates to a panel (3), in particular for a cowl of an aircraft propulsion unit, the panel comprising a sheet metal part (5) and a skin positioned facing one another, as well as an internal reinforcement structure (9) positioned between the sheet metal part (5) and the skin and comprising at least two stiffeners (11), the panel (3) comprising a channel (15) for circulating a cooling fluid (17), formed between the two stiffeners (11).

Description

[0001] DESCRIPTION

[0002] TITLE: Rigid heat exchanger panel for propulsion assembly and associated manufacturing process

[0003] technical field

[0004] The present invention relates to the cowling of a propulsion assembly of an aircraft.

[0005] In particular, the present invention relates to the cowling of a propulsion assembly comprising an unfaired propeller.

[0006] In general, the invention relates to any panel combining stiffness and heat exchange functionalities and is applicable to any use of this type.

[0007] Previous techniques

[0008] In an aircraft propulsion system, such as a turbomachine, and depending on the type of suspensions used to connect the turbomachine to the aircraft airframe, it may be necessary to transfer mechanical forces via a cowling of said propulsion system.

[0009] To this end, the covers of the propulsion assembly must therefore be made of rigid panels.

[0010] In parallel, particularly in the case of an unshrouded turbomachine, cooling the turbomachine is a challenge that is generally overcome by placing heat exchangers near the engine cowling walls. Such exchangers are not designed to transfer forces, take up space, and represent a significant additional mass.

[0011] Description of the invention

[0012] The present invention therefore aims to overcome the aforementioned disadvantages and to provide a rigid panel, particularly for propulsion assemblies, which both solves a problem of resistance to stress and allows for efficient cooling of the propulsion assembly.

[0013] The present invention relates to a panel, in particular for a cowling of an aircraft propulsion assembly, comprising a sheet metal and a skin positioned opposite each other and an internal reinforcement structure positioned between the sheet metal and the skin and comprising at least two stiffeners, the panel comprising a channel for the circulation of a cooling fluid made between the two stiffeners.

[0014] Thus, the spaces and channels formed between the stiffeners allow, in addition to an overall reduction in the mass of the panel, the introduction of a cooling fluid and the direct incorporation of a heat exchanger into the reinforcement structure of the panel according to the invention.

[0015] The heat exchanger formed by the panel is in particular a surface type heat exchanger, i.e. without fins, which uses the wall exposed to the airflow, namely the sheet metal, to exchange heat with the cooling fluid present in the circulation channels of the panel, said channels being in this case formed by the reinforcement structure.

[0016] Advantageously, the reinforcement structure is an isogrid or orthogrid type structure, each stiffener being in the shape of a triangle, or a rhombus, or a rectangle, or a hexagon.

[0017] In a particular embodiment, the reinforcement structure extends from the sheet metal, with each stiffener extending fully and orthogonally to the sheet metal.

[0018] In one embodiment, the panel has a radius of curvature of less than 5 meters, preferably less than 1 meter, the cooling fluid circulation channel having a generally orthoradial direction.

[0019] Advantageously, the panel includes a plurality of channels for circulating a cooling fluid between stiffeners, each channel having a cross-section whose size varies according to the distance separating said cross-section of said channel from an inlet point and / or an outlet point.

[0020] Advantageously, the sheet metal is intended to be positioned along an airflow of the propulsion assembly, the sheet metal comprising perforations each opening onto a resonant cavity formed in the reinforcement structure, each resonant cavity comprising a bottom formed by the skin and lateral surfaces formed by a stiffener.

[0021] In a particular embodiment, the panel includes a cooling fluid inlet and / or outlet point leading to a single cooling fluid circulation channel between two stiffeners, or including a cooling fluid inlet and / or outlet point connected to a distributor, respectively a manifold, leading to a plurality of cooling fluid circulation channels.

[0022] Advantageously, the panel includes at least one coolant drain channel.

[0023] Advantageously, the skin and / or the reinforcing structure and / or the sheet metal are made of metal, preferably in an aluminum alloy and / or in an aluminum-lithium alloy.

[0024] The present invention also relates to a propulsion assembly, particularly for aircraft, comprising a panel as defined above.

[0025] The present invention also relates to a method for manufacturing a panel as defined above, the method comprising the following steps:

[0026] - Shaping of sheet metal by rolling, or tensioning, or stamping, or turning, or hydroforming, or explosion forming;

[0027] - Machining of the sheet metal to form the reinforcement structure, the stiffeners being made from the same material as said sheet metal;

[0028] - Cutting and shaping the skin; and

[0029] - Assembly of the skin and the sheet metal by friction welding of the skin against the stiffeners, or by laser welding, or by brazing or gluing of the skin against the stiffeners.

[0030] Brief description of the drawings

[0031] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: [Fig 1]

[0032] is a schematic view of a streamlined turbomachine propulsion unit whose hood is formed by a panel according to the invention;

[0033] [Fig 2]

[0034] is a schematic view of a panel according to the invention without the skin;

[0035] [Fig 3]

[0036] is a schematic view of a panel according to the invention;

[0037] [Fig 4]

[0038] is a schematic view of a panel according to the invention comprising a distributor of a cooling fluid;

[0039] [Fig 5]

[0040] is a schematic view of a panel according to the invention comprising heat transfer fluid circulation channels wider than others;

[0041] [Fig 6]

[0042] is a schematic view of a panel according to the invention comprising obstructed heat transfer fluid circulation channels;

[0043] [Fig 7]

[0044] is a schematic view of a panel according to the invention comprising drainage channels;

[0045] [Fig 8]

[0046] is a schematic cross-sectional view of a panel according to figure 3;

[0047] [Fig 9]

[0048] is a schematic view of a panel according to the invention comprising acoustic perforations;

[0049] [Fig 10]

[0050] is a schematic cross-sectional view of a panel as shown in Figure 9 and including a thermal protection layer; and

[0051] [Fig H]

[0052] is a schematic view of the steps in the manufacturing process of the panel according to the invention.

[0053] Detailed description of at least one embodiment

[0054] Figure 1 schematically represents a propulsion unit 1, particularly for aircraft, comprising a panel 3 extending orthoradially around said propulsion unit 1 in the manner of a cylindrical hood.

[0055] In particular, the propulsion unit shown here is of the enclosed turbomachine type, but the invention could just as easily be applied to an unenclosed turbomachine.

[0056] According to the embodiment, the panel 3 can be positioned at various locations of a propulsion unit 1 illustrated in Figure 1, for example forming the passage for an internal air stream, for example the secondary stream VS downstream of the blower 4, or conversely forming an external hood or casing in contact with the external air of said propulsion unit 1.

[0057] Figures 2 and 3 schematically represent two views of a detail of a panel 3 according to the invention.

[0058] The panel 3 comprises a sheet 5 and a skin 7 positioned opposite each other and an internal reinforcing structure 9 positioned between the sheet 5 and the skin 7 and comprising at least two stiffeners 11.

[0059] As illustrated in Figure 2, only the sheet metal 5 and the reinforcement structure 9 are shown so as to identify the structure of said reinforcement structure 9.

[0060] Conversely, figure 3 represents skin 7 positioned against the reinforcement structure 9. Skin 7 is understood to be a thin sheet, preferably thinner than sheet 5.

[0061] The skin 7 and / or the reinforcing structure 9 and / or the sheet metal 5 are made of metal. Preferably, all these parts are made of metal to ensure sufficient rigidity.

[0062] The metal is preferably an aluminum alloy and / or an aluminum-lithium alloy. These metals are particularly advantageous for use in aeronautical applications. Indeed, these metals produce lightweight and heat-resistant panels.

[0063] The reinforcement structure 9 comprises a plurality of stiffeners 11 arranged in a pattern visible in Figure 2. Advantageously, the reinforcement structure 9 is an isogrid or orthogrid type structure, each stiffener 11 being triangular, rhombic, rectangular, or honeycomb-shaped, in other words, hexagonal. In particular, a stiffener 11 may have the general shape of two adjoining triangles forming a rhombus comprising a central portion 13 of the stiffener 11.

[0064] Triangles, for example, are isosceles or equilateral, and rectangles can be, in particular, squares. The hexagonal shape is preferably that of a regular hexagon.

[0065] These structures and shapes guarantee optimal mechanical resistance of panel 3 while requiring little material, and thus less mass carried by the aircraft.

[0066] The reinforcement structure 9 extends from the sheet 5, each stiffener 11 extending fully and orthogonally to the sheet 5.

[0067] The term "solid" means that the stiffeners 11 extend orthogonally to the sheet 5 without being perforated at any point.

[0068] Preferably, each stiffener 11 is an outgrowth of material from the sheet metal 5.

[0069] Advantageously, the stiffeners 11 are spaced apart so that the panel 3 includes a channel 15 for the circulation of a heat transfer fluid 17 made between two stiffeners 11. The heat transfer fluid 17 is also called the cooling fluid 17 and can also have the function of heating.

[0070] Each channel 15 is formed between the walls of two stiffeners 11 and the walls of the sheet 5 and the skin 7. Thus, the fluid 17 flows in contact with both the sheet 5, the skin 7 and the stiffeners 11.

[0071] As illustrated in Figure 2, the panel 3 comprises a plurality of stiffeners 11 and channels 15 for the circulation of a cooling fluid 17 interconnected and passing between the stiffeners 11.

[0072] Thus, panel 3 plays a dual role as a reinforcing structure and a heat exchanger.

[0073] Panel 3 is curved with a radius of curvature of less than 5 meters, preferably less than 1 meter. Consequently, each channel 15 for circulating the cooling fluid 17 has a generally orthoradial direction and follows the shape of said panel 3.

[0074] Panel 3 includes an inlet point 19 and an outlet point 21 for cooling fluid 17.

[0075] Two embodiments concerning the distribution of cooling fluid 17 are illustrated in figures 2 and 4.

[0076] In the first embodiment illustrated in Figure 2, a cooling fluid inlet 19 opens into a single channel 15 for the circulation of a cooling fluid 17 between two stiffeners 11.

[0077] In the second embodiment, the panel 3 includes a distributor 22 so that the inlet point 19 of cooling fluid 17 is connected to the distributor 22 which then opens onto a plurality of channels 15 for the circulation of a cooling fluid 17.

[0078] Depending on the circumstances, one or the other of these embodiments may be particularly advantageous for facilitating the passage of cooling fluid 17 at certain points. The same reasoning can be applied to the outlet point 21.

[0079] Figure 5 schematically represents a particular embodiment of the cooling fluid circulation channels 15, in which some of the circulation channels 15 are enlarged compared to others in order to promote a higher flow rate at certain locations or to compensate for pressure losses. For example, some channels 15 have a cross-section twice as large as others.

[0080] Preferably, the section of the first channels 15, namely the channels 15 closest to the entry point 19, have a different, in particular larger, section from the following channels 15 in order to promote the flow at the entry of the cooling fluid 17 into the panel 3.

[0081] Furthermore, the section of the channels 15 can be scalable so that the section of said channels 15 gradually decreases between the inlet point 19 and the outlet point 21 of the cooling fluid 17 in the panel.

[0082] In general, each channel 15 has, for example, a section whose size varies according to the distance between said section of said channel 15 and the entry point 19 and / or the exit point 21.

[0083] Figure 6 schematically illustrates another specific embodiment of the cooling fluid circulation channels 15, in which certain channels 15 are obstructed to prevent the circulation of fluid 17 in certain areas 23, for example, areas 23 that could be damaged in the event of a failure of the propulsion assembly 1, such as the bursting of a rotating part of the turbomachine. In other words, the reinforcement structure 9 comprises solid stiffeners 11 positioned across the channels 15 so as to obstruct them and prevent the circulation of cooling fluid 17 in the areas 23.

[0084] Optionally, panel 3 also includes a drain channel 25 for the cooling fluid 17. Two drain channels 25 for the cooling fluid 17 are schematically shown on either side of an outlet point 21 in Figure 7. Thus, when maintenance is required, the cooling fluid 17 can be drained through these drain channels 25, which are otherwise blocked by a drain plug.

[0085] Advantageously, sheet metal 5 is intended to be positioned along a gas flow, for example air.

[0086] The embodiment schematically illustrated in Figure 3, in which openings 26 in the skin 7 have a cross-section similar in size to that of a stiffener 11, makes it possible to reduce the aircraft's onboard mass. A cross-sectional view of this embodiment is also shown in Figure 8.

[0087] Alternatively, another embodiment is schematically illustrated in Figure 9.

[0088] In this embodiment, the sheet metal 5 includes perforations 27 each opening onto a resonant cavity 29 formed in the reinforcement structure 9, each resonant cavity 29 comprising a bottom 30 formed by the skin 7 and lateral surfaces 31 formed by a stiffener 11.

[0089] The perforations 27 in the sheet 5 have a cross-section much smaller than that of a stiffener 11. In this embodiment, a resonant cavity 29 can be fluidically connected to between 2 and 100 perforations 27 made in the sheet 5. A cross-sectional view of this second embodiment is also shown in Figure 10.

[0090] The resonant cavities 29 thus formed have acoustic properties which minimize noise in the vicinity of panel 3. It is therefore important that the perforations 27 be made on the side of panel 3 where the air is intended to flow, namely along the sheet 5.

[0091] Advantageously, the skin 7 can be thinner at the bottom 30 of each resonant cavity 29 in order to reduce the mass carried on board the aircraft.

[0092] Optionally, a thermal protection layer 33, for example quartz wool or a porous ceramic fiber assembly, can be installed against the sheet 5, for example in the case of an installation of the panel 3 around a fire zone or engine compartment.

[0093] Finally, Figure 11 shows the different stages of the manufacturing process of panel 3 as defined previously.

[0094] Initially, a shaping step El is performed on the sheet metal 5 by rolling, tensioning, stamping, turning, hydroforming, or explosion forming. This step El notably allows the sheet metal 5 to achieve the correct curvature.

[0095] Then, we carry out a step E2 of machining of the sheet 5 in order to form the reinforcement structure 9, the stiffeners 11 having come from the material with said sheet 5.

[0096] In parallel, we carry out step E3 of cutting and shaping the skin 7.

[0097] Finally, an E4 step is carried out of assembling the skin 7 and the sheet 5 by friction stir welding of the skin 7 against the stiffeners 11, or by laser welding, or by brazing or gluing of the skin 7 against the stiffeners 11.

[0098] Preferably, friction stir welding is preferred and a friction stir pin 34 passing in relation to the stiffeners 11 allows the said stiffeners 11 to be welded to the skin 7.

Claims

DEMANDS 1. Panel (3), in particular for a cowling of a propulsion assembly (I) of an aircraft, comprising a sheet (5) and a skin (7) positioned opposite each other and an internal reinforcing structure (9) positioned between the sheet (5) and the skin (7) and comprising at least two stiffeners (11), characterized in that it comprises a channel (15) for the circulation of a cooling fluid (17) made between the two stiffeners (11), the reinforcing structure (9) being an isogrid or orthogrid type structure, each stiffener (11) being in the shape of a triangle, or a rhombus, or a rectangle, or a hexagon, the reinforcing structure (9) extending from the sheet (5), each stiffener (11) being an outgrowth of material with the sheet (5) and extending in a solid and orthogonal manner to the sheet (5).

2. Panel (3) according to claim 1, comprising a plurality of channels (15) for circulating a cooling fluid (17) between stiffeners (11), each channel (15) having a cross-section whose size varies according to the distance separating said cross-section of said channel (15) from an inlet point (19) and / or an outlet point (21).

3. Panel (3) according to any one of claims 1 and 2, in which the sheet metal (5) is intended to be positioned along an airflow of the propulsion assembly, the sheet metal (5) comprising perforations (27) each opening onto a resonant cavity (29) formed in the reinforcement structure (9), each resonant cavity (29) comprising a bottom (30) formed by the skin (7) and lateral surfaces (31) formed by a stiffener (11).

4. Panel (3) according to any one of claims 1 to 3, comprising an inlet point (19) and / or an outlet point (21) of cooling fluid (17) opening onto a single channel (15) for circulating a cooling fluid (17) between two stiffeners (II), or comprising an inlet point (19) and / or an outlet point (21) of cooling fluid (17) connected to a distributor (22), respectively a manifold, opening onto a plurality of channels (15) for circulating a cooling fluid (17).

5. Panel (3) according to any one of claims 1 to 4, comprising at least one drain channel (25) for the cooling fluid (17).

6. Panel (3) according to any one of claims 1 to 5, wherein the skin (7) and / or the reinforcing structure (9) and / or the sheet metal (5) are made of metal, preferably of an aluminum alloy.

7. Propulsion assembly (1), in particular for aircraft, comprising a panel (3) according to any one of claims 1 to 6.

8. A method for manufacturing a panel (3) according to any one of claims 1 to 6, characterized in that it comprises the following steps: Sheet metal forming (5) by rolling, or tensioning or stamping or turning or hydroforming or explosion forming; Machining of the sheet metal (5) so as to form the reinforcement structure (9), the stiffeners (11) being made of the same material as said sheet metal (5); Cutting and shaping the skin (7); and - Assembly of the skin (7) and the sheet metal (5) by friction stir welding of the skin (7) against the stiffeners (11), or by laser welding, or by brazing or gluing of the skin (7) against the stiffeners (11).

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