Production of complex parts of a turbo engine combustion chamber using additive manufacturing and turbo engine combustion chamber

Description

Technical field

[0001] The invention relates, in the field of aeronautical turbomachines, to the production by additive manufacturing of fairly complex parts.

[0002] The production by additive manufacturing of at least one part of a gas turbomachine combustion chamber is thus concerned.

[0003] This production can in particular be carried out by additive manufacturing on a powder bed. Prior art

[0004] Additive manufacturing makes it possible to produce parts with relatively complex geometries without the constraints associated with the use of a mold, for example. However, these manufacturing processes are still limited by the long manufacturing time required, high manufacturing costs, and certain implementation difficulties.

[0005] FR3041889 and EP3002212 present solutions for producing parts using additive manufacturing, particularly on powder beds. The details of these production techniques can be transposed here.

[0006] FR3072448 also presents a method of production by additive manufacturing of at least one part of a gas turbomachine combustion chamber.

[0007] In this general context, the present subject relates specifically to the production of at least one part of a gas turbomachine combustion chamber by such a method.

[0008] In such a combustion chamber, to protect a wall from the effects of heat, it is known that the establishment of an air film is effective. This film can be obtained by a short double wall supplied with air through orifices (often called holes) which pass through one of the walls. The double wall directs the air along the surface to be protected in a fairly uniform manner.

[0009] An existing solution for producing such combustion chamber areas consists of independently manufacturing a piece of sheet metal which will define the inner lining wall of the outer wall of the body itself of the combustion chamber, then assembling, by welding or brazing, this piece of sheet metal to said body, while maintaining a space ensuring the air film.

[0010] This requires the parts to be assembled to be welded in such a way as to position them correctly.

[0011] After assembly, a calibration operation is necessary to ensure that the spacing between walls is adapted, in order to ensure a homogeneous flow of the air film.

[0012] These operations directly impact the cost and the production cycle.

[0013] The invention aims to resolve at least some of the aforementioned drawbacks. Summary of the invention

[0014] In order to improve the situation, the present document proposes a method of production by additive manufacturing of at least one part of an aeronautical turbomachine combustion chamber extending around an axis (marked X1 below) according to the subject of the claim

[0015] Thus, at the upstream end the radially inner wall will join the radially outer wall.

[0016] Such an upstream end connection, which can around the bottom of the combustion chamber, is important.

[0017] In fact, we will be able to produce the radially inner wall in the same part as the radially outer wall, whereas the manufacturing direction does not allow the production of a suspended wall.

[0018] The manufacture of these supports or holds formed by the succession of bridges becomes easy.

[0019] "Radially" means: radial with respect to the X1 axis. The radially outer wall is, in this direction, further from the X1 axis than the radially inner wall.

[0020] If, as is proposed elsewhere, said additive manufacturing is carried out on a bed of metal powder, using a laser, the bridges thus arranged will allow the laser energy to be dissipated and the metal to be solidified, which is necessary for the construction of the radially inner wall.

[0021] And this effect of energy dissipation, then of good air flow in the space between said walls respectively radially outer and radially inner, could be even better if, as also proposed, the radially outer wall and the radially inner wall are parallel to each other over a part of the length of the radially inner wall extending between its connecting ends respectively to the radially outer wall and to the bridges.

[0022] This does not prevent them from connecting to each other on the upstream side of the combustion chamber, the two walls being inclined relative to the axis X1, and therefore moving closer to this axis X1 towards the upstream, with therefore a steeper slope for the radially outer wall, towards the upstream end (on the figure 2 below face 30b can be almost perpendicular to the X1 axis).

[0023] This steeper slope of the radially outer wall (which can therefore be at the location of face 30b below), can belong to a bottom of the combustion chamber located, along the axis X1, at the upstream end of the combustion chamber, axially opposite the opening, centered on the axis X1, that the combustion chamber has, around the axis X1, at the downstream end, for the evacuation of hot gases from the combustion in the combustion chamber.

[0024] For the entry of combustion air and / or fuel (a priori fuel) into the combustion chamber, the aforementioned base may be annular, with a central passage centered on the X1 axis.

[0025] Perpendicular to the X1 axis, the section of this central passage will be less than the section of the hot gas discharge opening.

[0026] Additive manufacturing allows that by continuing the deposition of layers of said material after the manufacture of a lower zone of combustion chamber as explained above, we continue to create, annularly around said axis (X1): the radially outer wall, the radially inner wall, and the bridges arranged next to each other towards the end of the radially inner wall opposite that where the radially inner wall joins the radially outer wall, this: -- by making, around the axis (X1), said respectively radially outer and radially inner walls polygonal (other parts of these walls), and -- by tilting the bridges (other said bridges) so that they extend between said respectively radially outer and radially inner walls transversely to the side of the polygon where these bridges are arranged.

[0027] Thus inclined, at least some of the bridges considered will extend, between said walls respectively radially outer and radially inner, not perpendicularly, but rather obliquely with respect to the side concerned. Angles therefore other than 90°, such as between 10° and 80°, are implemented.

[0028] To supply air to the space created between the radially outer and radially inner walls, openings will usefully be reserved in the radially outer wall which can open into this space.

[0029] The orientation of at least some of these orifices will be generally parallel to said axis (X1), for efficient air sweeping.

[0030] In addition to the method presented above, the invention also relates to a gas turbomachine combustion chamber according to the subject of claim 5.

[0031] Thus, with respect to the axis (X1), the radially outer wall will favorably present a steeper slope towards its upstream connection end than further downstream, towards said free end.

[0032] It will of course be understood that the "upstream connecting end" above is the (upstream) end of the radially outer wall where it connects - joins - the upstream connecting end of the radially inner wall.

[0033] Further downstream of their respective “upstream connection ends”, the radially inner and radially outer walls may usefully become substantially parallel, thus making it possible to avoid, at the free end of the radially inner wall, a so-called intermediate space and therefore an inappropriate air film, because it occupies too small a space.

[0034] Among the characteristics of this combustion chamber, it will be noted that individual bridges, extending alongside each other, connect the radially inner wall and the radially outer wall towards a free end of the radially inner wall, this: in a single piece and in such a way that the bridges and, at least locally, the radially inner wall and the radially outer wall are obtained by stacking successive layers; technique often called “additive layer structure”.

[0035] As before, this should improve the situation in the face of at least some of the aforementioned disadvantages.

[0036] The expression "with additive layer structure" has the meaning of a single block, but also: "produced by additive manufacturing", therefore with a physicochemical structure specific to this manufacturing and which can be recognized by a physicochemical analysis of this structure and therefore differentiated in particular from manufacturing by casting or injection.

[0037] In order to promote peripheral continuity (around the X1 axis) for maintaining the film wall and a homogeneous passage of air, it is also proposed that, on this combustion chamber, at one end where they connect to the radially inner wall, the bridges flare: until they come into contact two by two and / or up to an angle less than 150° or between 120° and 160°.

[0038] Concerning the air openings in the radially outer wall, which will therefore open between said radially outer and radially inner walls, it is even proposed: that they are formed on several faces of the radially outer wall, along several parallel lines, and / or, that they individually have the shape of a convex pentagon.

[0039] Finally, the invention also concerns an aeronautical turbomachine comprising the combustion chamber provided with all or part of the above characteristics. Concerning additive manufacturing, this technique therefore groups together the processes for manufacturing parts in volume by adding or agglomerating material, by stacking successive layers. From a computer-aided design, specific software organizes a cutting into slices of the different layers necessary for the production of the part. The use of several materials can make it possible to obtain a part whose thermal expansion is zero and / or is controlled, or other physical properties. A step of hot isostatic pressing, cold isostatic pressing or vacuum densification isostatic pressing can be provided, to promote the production of parts which do not have, in particular, anisotropy or unwanted porosity.The part may comprise a metal alloy and / or a ceramic material. Brief description of the drawings

[0040] [ Fig. 1 ] there figure 1 schematizes a possible embodiment of a solution in accordance with the invention, by illustrating a lower upstream part of the combustion chamber of an aeronautical turbomachine, in perspective and axial section (axis X1). [ Fig. 2 ] there figure 2 schematizes the section of the figure 1 view following the arrow Island, following. [ Fig. 3 ] there figure 3 schematizes the section of the figure 1 view following arrow III. [ Fig. 4 ] there figure 4 represents the view of the figure 1 view following arrow IV. [ Fig. 5 ] there Figure 5 is a rough axial sectional diagram of the aforementioned combustion chamber. Description of the embodiments

[0041] In the following description, like reference numerals designate like parts or parts having similar functions.

[0042] An object of the invention is therefore, marked 1 in the figures ( Figure 5 in particular), an aeronautical turbomachine combustion chamber (gas).

[0043] As known, such a combustion chamber 1 is interposed between, upstream with respect to the general direction of circulation of the gases in the turbomachine, a compressor and, downstream, a turbine.

[0044] Upstream, an air and fuel injection system supplies the combustion chamber with air and fuel. A fraction of the upstream air from the compressor is guided through the injection system, to form a fuel mixture injected along an X1 axis. The mixture passes into an internal primary zone of the combustion chamber where the combustion reactions take place, then the gases produced are diluted and cooled in a secondary zone, further downstream, and are then distributed to the turbine which they drive.

[0045] X1 is also the axis around which the combustion chamber 1 extends from upstream to downstream.

[0046] The combustion chamber 1 therefore has, along the axis X1, at the upstream end, a bottom crossed by a central passage and, at the downstream end, an opening for discharging hot gases; see Figure 5 .

[0047] As can also be noted Figure 5 , perpendicular to the axis X1, the section of the central passage is preferably smaller than the section of the hot gas discharge opening.

[0048] The gas turbomachine equipped with the combustion chamber 1 can be a double-flow, double-spool turbojet, therefore provided, from upstream (AM) to downstream (AV), with a fan, a low-pressure compressor, a high-pressure compressor, an annular combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0049] As illustrated in particular by the figure 1, the combustion chamber 1 comprises, around the axis X1, a radially outer wall 3 locally doubled by a radially inner wall 5.

[0050] Thus, an intermediate space 7 exists between the radially outer 3 and radially inner 5 walls. An air film can be created between the walls.

[0051] To manufacture the radially inner wall 5 in the same part as the radially outer wall 3, bypassing the difficulty of producing a suspended wall, individual bridges 9, extending alongside each other, connect the radially inner wall 5 and the radially outer wall 3 in a single piece, towards a free end 5a of the radially inner wall 5.

[0052] In other words, the bridges 9 and, at least locally, as in the lower zone 10 of the combustion chamber 1 ( Figure 5), the radially inner wall 5 and the radially outer wall 3 are made of a single piece and have a common structure of additive layers.

[0053] In order to promote peripheral continuity (around the axis X1) of maintenance (support for said lower zone 10) of the radially inner wall 5 and a homogeneous passage of air in the intermediate space 7, the presence of bridges 9 flaring at one end (or top) 9a where they connect to the radially inner wall 5 may be useful.

[0054] In particular, the bridges 9 can then flare: until coming into contact two by two (zone 11) figure 3 ), and / or up to an angle A less than 150° or between 120° and 160°.

[0055] It is a compromise between the capacity of additive manufacturing and the mechanical effect to be achieved.

[0056] To further promote a homogeneous (fairly stable) air passage, the following is implemented: that around the axis X1, said radially outer 3 and radially inner 5 walls have polygonal faces (see figure 4 ), and that, perpendicular to the direction in which the bridges 9 connect said inner 5 and outer 3 walls, and perpendicular to the direction (Y1) in which these walls 3 and 5 extend around said axis X1, the bridges 9 are elongated (direction Xp figure 1 ) and each have double beveled ends 9b1, 9b2.

[0057] The refined ends 9b1, 9b2 are aerodynamic and longer (Xp direction) than wide bridges 9 stabilize the flow of air from upstream to downstream.

[0058] Reserving, in the radially outer wall 3, openings 13 opening into the intermediate space 7 will ensure circulation conducive to the creation of the desired air film along the internal face of the radially outer wall 3.

[0059] Regarding these 13 openings, it is even proposed: that they are formed on several faces, such as 30a, 30b, of the radially outer wall 3, preferably along several lines parallel to each other, and / or, that they individually have a convex pentagon shape (see figure 1 ).

[0060] The convex, double-sloped part 13a of each convex pentagon will preferably be located closer to the X1 axis than the other sides of the pentagon.

[0061] Thus, we will usefully combine a production of the walls 3.5 with polygonal faces, adapted to additive manufacturing, and a distribution of the openings 13 distributed around the axis X1, with optimized mechanical strength (convex pentagon shape).

[0062] Concerning the production of at least one part of a combustion chamber, such as part 1, we will have noted the marked interest in the fact that, due to additive manufacturing, this takes place from the bottom to the top (respectively L and H, and arrow, figure 2 ).

[0063] Thus, while, by depositing a succession of layers of material, a lower part 30 (lower zone 10) of said radially outer wall 3 will be created, the deposition of such layers of material will continue to raise, on said lower part, bridges 9 then erected next to each other up to the summits 9a of these bridges.

[0064] Once this is achieved, we can continue to deposit layers of material to create (initiate the creation of) the radially inner wall 5, while continuing to create the radially outer wall 3.

[0065] Gradually, the said deposits of layers of material will then continue, at least until the said lower part 30 of the radially outer wall 3 and an end 5b of the radially inner wall 5 opposite (parallel to the axis X1) to that 5a where the bridges 9 are located join.

[0066] Thus, in the lower zone 10, the radially inner wall 5 is inclined relative to the axis X1 and rises towards its end 5b connecting to the radially outer wall 3.

[0067] Opposite, the radially outer wall 3 is also inclined relative to the axis X1.

[0068] Preferably, for a compromise between manufacturing, mechanical strength, aerodynamic effect, it is advisable in this regard that the radially outer wall 3 and the radially inner wall 5 are parallel to each other, over the majority of the length L of the radially inner wall 5 extending between said ends 5a and 5b.

[0069] On the rest of the perimeter (closed, therefore of the perimeter) of the radially outer 3 and radially inner 5 walls, if the aforementioned manufacturing technique is also used, it is advisable to proceed in the same way: tilt the two walls 3 and 5 relative to the axis X1, but then with reversed directions of progression in the upper part of said walls 3, 5, and therefore of the combustion chamber 1, namely by raising the radially inner wall 5 from its end 5b connecting to the radially outer wall 3 towards its free end 5a where the bridges 9 will be raised until they connect to the radially outer wall 3 which the ongoing layer deposits will have continued to create in the meantime.

[0070] On this subject, we will also have noted the interest of the compromise (between manufacturing, mechanical strength and aerodynamic impact) in that, while continuing the deposits of layers of said material, we continue to create, annularly around the axis X1, the radially outer wall 3, the radially inner wall 5 and the bridges 9 then arranged next to each other, towards the free end 5a of the radially inner wall 5, this: by making, around the axis X1, said radially outer 3 and radially inner 5 polygonal walls, and by tilting the bridges 9 so that these bridges extend between said radially outer 3 and radially inner 5 walls, transversely to the side (or face) of the polygon where they are arranged; see for example figure 2: bridges 9 which can be erected vertically between the face 30a of the radially outer wall 3 and the substantially parallel face 50a of the radially inner wall 5, these two faces being inclined relative to the axis X1, approaching this axis X1 towards the upstream.

[0071] Transversely here does not mean perpendicular, but rather inclined relative to the side concerned.

Claims

1. Method of production by additive manufacturing of at least one part of a combustion chamber of an aeronautic turbomachine extending around an axis (X1) and comprising a radially outer wall (3) which is lined locally by a radially inner wall (5) so as to form an intermediate space (7) between them which can create a film of air, characterised in that, from bottom to top and by additive manufacturing: - while a lower portion (30) of said radially outer wall (3) is created by depositing a succession of layers of material, the deposition of layers of said material is continued in order to erect, on said lower portion, bridges (9) which are raised next to one another up to the tops (9a) of said bridges, where - the deposition of layers of said material is continued in order to create, annularly around the axis (X1), the radially inner wall (5), while continuing with said creation of the radially outer wall (3), and - said deposition of layers of material is further continued, at least until said lower portion (30) of the radially outer wall (3) joins an end (5b) of the radially inner wall that is opposite the end where the bridges (9) are located, doing so: - while creating, polygonally around the axis (X1), said radially outer wall (3) and radially inner wall (5), and - while creating the bridges such that they extend in an inclined manner between said radially outer wall and radially inner wall, not perpendicular to the side of the polygon where they are arranged, such that the bridges (9) are arranged next to one another towards the end (5b) of the radially inner wall that is opposite the end where the radially inner wall (5) joins the radially outer wall (3).

2. Method according to claim 1, wherein said additive manufacturing is carried out on a metal powder bed.

3. Method according to claim 1 or 2, wherein the radially outer wall (3) and the radially inner wall (5) are parallel to one another over part of the length of the radially inner wall extending between said ends.

4. Method according to any of the preceding claims, wherein openings (13) are reserved in the radially outer wall (3), which lead to between the radially outer wall (3) and the radially inner wall (5).

5. A combustion chamber of a gas turbomachine having an axis (X1) along which it has an upstream side and a downstream side, the combustion chamber comprising: - about said axis (X1), a radially outer wall (3) lined locally by a radially inner wall (5) so as to form an intermediate space (7) between them which can create a film of air, - customised bridges (9), which extend next to one another and which connect the radially inner wall and the radially outer wall as one piece, characterized in that: - the radially inner wall (5) is thus connected to a free end (5a), - the two walls, respectively radially outer (3) and radially inner (5) walls, are connected to one another, upstream, towards an end opposite to said free end (5a), and therefore not perpendicular but inclined relative to the axis (X1) by drawing closer to the axis (X1) in the upstream direction, with a steeper slope of the radially outer wall towards said upstream connecting end, - around the axis (X1), said radially outer wall (3) and radially inner wall (5) have polygonal faces, and between said radially outer wall and radially inner wall, the bridges extend in an inclined manner, not perpendicular to the side of the polygon where they are arranged, - perpendicularly to the direction in which they connect the radially inner wall and the radially outer wall and to the direction in which said radially inner wall (5) and radially outer wall (3) extend around said axis (X1), the bridges (9) being elongate and having ends which are each double-bevelled.

6. Combustion chamber according to claim 5, wherein, at an end where they are joined to the radially inner wall (5), the bridges (9) flare out until they come into contact in pairs and / or to an angle of less than 150° or between 120° and 160°.

7. Combustion chamber (1) according to claim 5 or 6 having openings (13) in the radially outer wall (3) which lead to between the radially outer wall and the radially inner wall.

8. Combustion chamber according to one of claims 5 to 7, wherein the openings are formed on a plurality of faces of the radially outer wall (3), along to a plurality of parallel lines, and / or individually having a convex pentagonal shape.

9. Aeronautic turbomachine comprising the combustion chamber (1) according to any of claims 5 to 8.