EP1717516B1 - Easily disassembled combustion chamber with improved aerodynamic performance - Google Patents

Description

The invention relates to a combustion chamber for a reactor. It relates more particularly to an improvement in the assembly of the different parts of the combustion chamber, with the dual aim of reducing the disturbances of the air flow around it, which may penalize its performance, and to facilitate the maintenance.

A known combustion chamber is a divisible assembly of several parts. There is a generally annular outer wall, a generally annular inner wall and a bottom wall extending between said outer and inner walls. The fuel injection means are mounted on said bottom wall of the chamber. They consist of a plurality of injection systems spaced circularly. In addition, a fairing defines with said bottom wall of chamber an annular cavity housing these injection means. The combustion chamber thus defined is an axisymmetric assembly which must be as aerodynamic as possible since placed in the air stream. The shroud generally comprises an annular piece called outer cap and an annular piece called inner cap. The various components of the combustion chamber are assembled together removably. For example, it is known to assemble said outer and inner walls, said bottom wall of the chamber and the elements of the fairing by a bolt ring arranged in the vicinity of the bottom wall of the chamber. Bolt heads disturb the flow of air. This disturbance penalizes the performance of the combustion chamber.

In some combustion chambers, the bolting assembly is replaced by a set of welds between said inner and outer walls, the bottom wall of the chamber and the fairing. In this type of combustion chamber, there are no more screw heads to disturb the flow at the external bypass or at the internal bypass of the combustion chamber. On the other hand, the welds make this combustion chamber difficult to repair because it is necessary at least to cut said chamber according to two circular welds. As these welds are on cones, it is very difficult and expensive to reassemble the chamber after repairing an element thereof. The document EP1265033 A1 discloses all the features of the preamble of claim 1.

The invention overcomes this double difficulty.

More specifically, the invention relates to a combustion chamber of a reactor comprising a generally annular outer wall, a generally annular inner wall, a chamber bottom wall extending between said outer and inner walls and on which are mounted means injection molding and a shroud defining with said bottom wall of an annular chamber chamber housing said injection means, said fairing comprising an annular piece said outer cap and an annular piece called inner cap, characterized in that said caps comprise parts internal fasteners projecting into said annular cavity, in that said bottom wall of the chamber comprises corresponding internal fasteners protruding inside said annular cavity and in that the fasteners of said caps. are assembled to the fasteners of said bottom wall of room.

The aforementioned internal fasteners are tabs distributed circumferentially or, more generally, ferrules.

For example, if tongues are used, those of said caps and those of said bottom wall of the chamber are welded. Preferably, they are welded two by two together at their ends only. Under these conditions, a possible disassembly of the components of the combustion chamber can be easily done by grinding the ends of the tongues so as to eliminate the welded areas.

Separating the tabs divides the combustion chamber into several parts, making repairs to any of these parts possible.

If the fasteners are ferrules, it is advantageous to maintain a sectorized assembly, as if it were tongues, for example by producing a plurality of welds regularly distributed circumferentially. We can combine ferrules and tongues.

According to an advantageous embodiment, said outer cap and said outer wall are assembled circumferentially by welding. The welding can be done singing against singing.

Advantageously, the inner wall and the bottom wall of the chamber are secured circumferentially. The assembly can be achieved by riveting or even capping.

The weld joining the tongues together is preferably a TIG weld, known per se. A high intensity current passes through a tungsten electrode forming an arc with the parts to be assembled. The metal receiving the arc undergoes a local fusion. The welding is done in a neutral gas environment (argon for example).

The tongues carried by the caps are preferably assembled to them by brazing. Each tab is assembled to the cap by means of a filler metal whose melting point is less than the melting point of the materials to be assembled. The assembly is performed without melting the metal of the elements to be assembled. Once brought to the melting temperature, the filler metal enters by capillary attraction between the parts to be assembled. The filler metal is preferably based on nickel for a brazing temperature of the order of 1160 ° C.

According to yet another optional feature, the inner cap has an annular band in contact enveloping with the end portion of the inner wall.

• la figure 1 est une vue partielle en perspective d'une chambre de combustion conforme à l'invention ;
• la figure 2 est une vue analogue à la figure 1 dans laquelle les moyens d'injection ont été enlevés pour mieux montrer l'assemblage des différentes parties constitutives de la chambre de combustion ; et
• la figure 3 est une section radiale à plus grande échelle de la figure 2.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the description which follows, given solely by way of example and with reference to the appended drawings in which:

• the figure 1 is a partial perspective view of a combustion chamber according to the invention;
• the figure 2 is a view similar to the figure 1 wherein the injection means have been removed to better show the assembly of the various constituent parts of the combustion chamber; and
• the figure 3 is a radial section on a larger scale of the figure 2 .

In the drawings, there is shown partially the front part of a combustion chamber 11, which consists of the assembly of several annular parts. There is a generally annular outer wall 12, a generally annular inner wall 13, a chamber bottom wall 14 extending between said outer walls and inside and on which are mounted the injection means 21 and a shroud 15 comprising an annular piece called said outer cap 16 and an annular piece said inner cap 17. The shroud defines with said bottom wall of a chamber annular cavity 20 housing the means injection. These consist of a plurality of injectors 22 circumferentially spaced regularly and mounted on the bottom wall of chamber 14.

The invention relates more particularly to the method of assembly between said inner and outer walls, the bottom wall of the chamber and the two caps.

More particularly, the caps 16, 17 comprise tongues 24, 25, respectively, projecting inside the annular cavity 20. These tongues are regularly distributed circumferentially. Each cap has as many tabs 24 or 25 as there are injectors but they are offset circumferentially relative to the injectors for better accessibility in case of disassembly. A tongue 24 or 25 has a curved portion 28 conforming to the shape of the inner face of the cap and a portion 29 curved radially inward, which protrudes into the annular cavity. The bottom wall of the chamber also has tabs 34, 35 projecting into the annular cavity. The chamber bottom wall 14 and the tongues 34, 35 carried by it, inside and outside, are drawn from the same cut and stamped sheet as can be seen on FIG. figure 2 . There are a series of outer tongues 34 and a series of inner tongues 35. The outer tongues 34 of the chamber bottom wall and the tongues 24 of the outer cap are equal in number and correspond, each tongue of the cap being applied. by its projecting portion against a corresponding tongue of the chamber bottom wall. Similarly, the tongues 25 of the inner cap and the inner tongues 35 of the bottom wall of the chamber are equal in number and correspond, each tongue of the inner cap being applied by its projecting portion against the corresponding tongue of the wall of the bedroom background. In these positions, the tongues of said caps are assembled to the tongues of said bottom wall of the chamber. More particularly, the tongues of said caps and those of said chamber bottom wall are welded in pairs and preferably only at their ends. As mentioned above, the solder 40 is preferably of the TIG type. On the other hand, the parts of the tongues 24, 25 secured to the caps 16, 17 are joined thereto by brazing. Because the tongues are bent so as to be placed side by side in pairs and welded only at their ends, it is relatively easy to separate them, for example by grinding said welded ends. . These grinding operations will disassemble the various parts of the combustion chamber for repairs. After these repairs reassembly is possible by re-welding the ends of the slightly shortened tabs 24, 34 and 25, 35.

Furthermore, the outer cap 16 and said outer wall 12 are joined circumferentially by welding. As shown, the weld 42 is edge-to-edge so that the flow of air outside the combustion chamber is not disturbed. The chamber bottom wall 14 is not attached to said outer part.

On the other hand, the inner wall 13 and said bottom wall chamber 14 are secured circumferentially. In the embodiment described, the two walls are shaped with annular bands 43, 44 in contact. These strips can be secured by riveting or capping. Said inner cap 17 also comprises an annular band 47 in contact enveloping with the annular band of said inner wall. It is not attached to this inner wall. This arrangement does not substantially disturb the flow of air within the vein defined by the inner wall and the inner cap of the combustion chamber. Said inner wall 13 and the inner cap 17 are not secured in their contact zone.

An assembly using ferrules would, in section, have a configuration in accordance with the figure 3 .

Claims (12)

1. A jet engine combustion chamber comprising a generally annular outer wall (12), a generally annular inner wall (13), a chamber end wall (14) extending between said outer and inner walls and having injector means mounted thereon, and a fairing co-operating with said chamber end wall to define an annular cavity (20) that houses said injector means, said fairing comprising an annular part referred to as an "outer cap" (16) and an annular part referred to as a "inner cap" (17), wherein said caps include inner fastener parts (24, 25) projecting into said annular cavity, wherein said chamber end wall includes corresponding inner fastener parts (34, 35) projecting into said annular cavity, and wherein the fastener parts of said caps are assembled directly to the fastener parts of said chamber end wall, characterized in that said inner fastener parts are tongues that are distributed circumferentially.
2. A combustion chamber according to claim 1, characterized in that the tongues (24, 25) of said caps and the tongues (34, 35) of said chamber end wall are welded together.
3. A combustion chamber according to claim 1 or claim 2, characterized in that both said tongues of said caps, and said tongues of said chamber end wall are curved in such a manner as to extend side by side in pairs one against the other, and in that they are welded together in pairs at their ends (40).
4. A combustion chamber according to claim 1, characterized in that said inner fastener parts are circumferentially distributed tongues combined to annular rims.
5. A combustion chamber according to any preceding claim, characterized in that said outer cap (16) and said inner wall (12) are assembled together circumferentially by welding (42).
6. A combustion chamber according to claim 5, characterized in that said outer cap (16) and said inner wall (12) are butt welded together.
7. A combustion chamber according to any preceding claim, characterized in that said inner wall (13) and said chamber end wall (14) are united circumferentially.
8. A combustion chamber according to claim 7, characterized in that said inner wall and said chamber end wall are shaped with contacting annular margins (43, 44) that are untied by riveting or by an interference fit.
9. A combustion chamber according to any preceding claim, characterized in that said chamber end wall (14) and the tongues (34, 35) carried thereby are portions of a single sheet of metal that has been cut and stamped.
10. A combustion chamber according to any one of claims 1 to 3, characterized in that the tongues (24, 25) carried by said caps are assembled thereto by brazing.
11. A combustion chamber according to claim 8, characterized in that said inner cap includes an annular margin (47) in covering contact with said annular margin (43) of said inner wall.
12. A jet engine characterized by comprising a combustion chamber according to any preceding claim.

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