The invention relates to a method of fabricating a combustion chamber by assembling together preformed shells; more particularly the invention relates to the way in which assembly is performed, eliminating any need for seam welding. The invention applies advantageously to fabricating so-called “reverse-flow” combustion chambers.
The invention also relates to a forward-flow combustion chamber obtained by implementing the method, and to a turbojet fitted with a combustion chamber of the invention.
A so-called reverse-flow combustion chamber is generally made up of metal sheet stamped to constitute shells. The shells are assembled together. For assembly purposes, the shells often have annular tongues that are assembled flat thereto by seam welding.
These welded-on tongues project outside the combustion chamber, thereby leading to head losses in the stream of air flowing around the combustion chamber. In addition, mechanical weakness remains in these tongues, particularly in a reverse-flow combustion chamber, while the outer bend of the chamber is being subjected to bending.
In addition, that assembly technique leads to thermomechanical stresses and raises problems of accessibility if it is desired to use a laser to perforate the combustion chamber.
Attempts have recently been made to reduce the number of annular tongues by making use of butt welded assembly techniques. Nevertheless, the solutions that have been envisaged until now have not made it possible completely to eliminate seam welding.
The invention makes it possible to achieve that objective.
More particularly, the invention provides a method of fabricating a combustion chamber essentially made up of welded-together shells, the method comprising:
making separately two subassemblies of such shells by butt-welding the shells together, with an intermediate connection ring being welded to one end of a first subassembly, the intermediate ring including an assembly surface;
engaging one end of a second subassembly on said surface; and
welding it to said intermediate ring.
In order to fabricate a so-called “reverse-flow” combustion chamber, the first subassembly is mainly constituted by outer shells and the second subassembly is mainly constituted by inner shells. The shells of each subassembly are assembled together by butt-welding. A flat-bottomed shell constitutes a chamber end wall for carrying the injectors, and this chamber end wall constitutes a portion of one of the subassemblies prior to final welding.
By way of example, one of the subassemblies includes such a chamber end wall and one of the ends of said chamber end wall constitutes the end of said second subassembly that is to be welded to said intermediate ring.
In a manner that is itself known, butt-welding is always performed by adjusting the docking of the two annular parts concerned by means of radial expander tools that enable the parts to be abutted edge to edge for welding purposes.
The intermediate connection ring is a part that is machined at least in part, having accurate dimensions. It can therefore perform a centering function at the moment when the two subassemblies are finally assembled together by orbital welding. Such assembly can be performed by laser welding or by tungsten inert gas (TIG) welding.
In addition, the intermediate connection ring itself includes or constitutes the filler metal needed for welding to the second subassembly.
A combustion chamber of the invention is thus made up of a plurality of preformed shells including a chamber end wall, which shells are assembled together by butt-welding with the exception of a junction between two subassemblies of such shells, said junction being made by interposing an above-mentioned intermediate connection ring.
The invention can be better understood and other advantages thereof appear more clearly in the light of the following description of a method of fabricating a “reverse-flow” combustion chamber in compliance therewith, given purely by way of example and made with reference to the accompanying drawings, in which:
The drawings briefly described above are diagrammatic half-sections showing annular shells or other annular parts united in succession to make up a reverse-flow combustion chamber. With the exception of the welding shown in
The butt-welding mentioned with reference to
In
As shown in
As shown in
At the end of the operation shown in
In accordance with the operation shown in
In accordance with
Thereafter, in accordance with
At the end of the operation shown in
In accordance with
It should be observed that, given the structure of the intermediate connection ring, the final welding operation does not disturb the flow of air around the combustion chamber.
In addition, the fact that the combustion chamber obtained in this way has a “smooth” outer wall makes it easier to position the laser equipment used for making the multiple orifices perforated in the wall of the combustion chamber.
The type of welding used ensures best possible thermomechanical behavior for the combustion chamber. Fabrication cost is reduced.
Number | Date | Country | Kind |
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06 50352 | Feb 2006 | FR | national |
Number | Name | Date | Kind |
---|---|---|---|
4195475 | Verdouw | Apr 1980 | A |
4458481 | Ernst | Jul 1984 | A |
6986452 | Dracup et al. | Jan 2006 | B2 |
7168606 | Badrak | Jan 2007 | B2 |
7241961 | Duret et al. | Jul 2007 | B2 |
Number | Date | Country |
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791752 | Mar 1958 | GB |
Number | Date | Country | |
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20070175029 A1 | Aug 2007 | US |