Combustion chamber in a turbomachine
View Patent ↗A turbomachine combustion chamber has primary and dilution air inlet orifices formed by die stamping to have edges that project into the inside of the combustion chamber, and stress relaxation and/or reduction means in the edges or in the vicinity of the edges of said orifices, said means comprising, for each orifice, one, two, or three slots formed in the edge or around a fraction of the edge of said orifice.
1. A combustion chamber for a turbomachine, the chamber comprising:
an outer coaxial circularly-symmetrical wall;
an inner coaxial circularly-symmetrical wall extending inside the outer wall;
an annular chamber end wall which connects the inner wall and the outer wall at upstream ends of the inner and outer walls;
primary air inlet orifices and dilution air inlet orifices disposed on the inner and outer walls which are formed by die stamping, the orifices including edges projecting into the inside of the chamber; and
stress relaxation or reduction means in the edges or in the vicinity of the edges of at least some of said orifices, said stress relaxation or reduction means consisting, for each orifice, of one, two, or three slots formed in the edge or around a portion of the edge of said orifice, each slot being connected at least one of its ends to a crack propagation stop orifice,
wherein the slots include inner walls and the stop orifices include inner walls, said inner walls of the slots and of the stop orifices being inclined relative to a normal to the inner or outer wall and are substantially parallel to inner walls of microperforations formed in said inner or outer wall for cooling the chamber by air flowing through the slots, the stop orifices and the microperforations.
2. A chamber according to claim 1 , wherein the slots extend from the edges of the orifices to crack propagation stop orifices.
3. A chamber according to claim 2 , wherein the slots formed in the edge of an orifice are symmetrical about a plane containing the axis of said orifice and the axis of the chamber.
4. A chamber according to claim 2 , wherein the slots formed in the edge of an orifice are regularly distributed around the axis of the orifice.
5. A chamber according to claim 2 , wherein the slots are rectilinear or curved in shape.
6. A chamber according to claim 1 , wherein the slots are formed around a portion of the edges of the orifices and have a crack propagation stop orifice at each end.
7. A chamber according to claim 6 , wherein a portion of each slot is of undulating shape and presents triple curvature.
8. A chamber according to claim 6 , wherein a portion of each slot is formed by a circular arc centered on the axis of an orifice.
9. A chamber according to claim 8 , wherein the end portions of the slot formed around the edge of an orifice are directed outwards away from the axis of said orifice.
10. A chamber according to claim 1 , wherein the stop orifices are of a diameter lying in the range about 1 mm to about 2 mm.
11. A chamber according to claim 1 , wherein the slots are of width less than about 1 mm.
12. A chamber according to claim 1 , wherein the slots and/or the stop orifices are formed by laser cutting.
13. A chamber according to claim 1 , wherein at least some of the air inlet orifices are oval in shape with a long axis situated in a plane parallel or perpendicular to the axis of the chamber.
14. A chamber according to claim 13 , wherein the long sides of the orifices are situated in the zones most subject to cracking.
15. A turbomachine, such as an aircraft turbojet or turboprop, the turbomachine including a combustion chamber according to claim 1 .
16. A chamber according to claim 1 , wherein an axial position of some the microperforations formed in said inner or outer wall is the same as an axial position of the primary inlet orifices or the dilution air inlet orifices.