Combustion chamber for a turbomachine

Abstract

A combustion chamber for a turbomachine having a bottom wall, at least one mixing bowl for promoting the mixing of air and fuel, mounted in an opening in the bottom wall, at least one annular baffle mounted axially downstream of the bottom wall, with respect to the direction of the gas flow within the combustion chamber, around the opening. The baffle is produced in one piece with the mixing bowl so as to form a one-piece assembly that has at least one channel for the flow of cooling air. The channel has an air inlet located upstream of the bottom wall and an air outlet located downstream of the bottom wall. The air outlet is located radially opposite the baffle.

Claims

1. A combustion chamber for a turbomachine having a bottom wall, at least one mixing bowl for promoting the mixing of air and fuel, mounted in an opening in the bottom wall, at least one annular baffle mounted axially downstream of the bottom wall, with respect to the direction of the gas flow within the combustion chamber, around said opening, the baffle being produced in one piece with the mixing bowl so as to form a one-piece assembly, wherein said assembly comprises at least one channel for the flow of cooling air, said at least one channel comprising an air inlet located upstream of the bottom wall and an air outlet located downstream of the bottom wall, wherein the at least one channel is perpendicular to the baffle.

2. The combustion chamber according to claim 1, wherein said assembly comprises a cylindrical attachment part, attached to the bottom wall and mounted radially inside the opening, the baffle comprising a radially inner base part connected to said attachment part, the channel being provided in the cylindrical attachment part, the air outlet of the channel being located opposite a base of the baffle.

3. The combustion chamber according to claim 1, wherein the combustion chamber comprises at least one air intake swirler capable of generating a rotary air flow, located upstream of the mixing bowl.

4. The combustion chamber according to claim 2, wherein the attachment part extends axially in the upstream direction from the radially outer periphery of the mixing bowl, the baffle extending radially outwardly from the radially outer periphery of the mixing bowl.

5. The combustion chamber according to claim 1, wherein the assembly comprises a plurality of channels intended for the flow of cooling air, evenly distributed over the circumference.

6. The combustion chamber according to claim 1, wherein the cross-section of each channel is substantially constant from the upstream end of said channel to the downstream end of said channel.

7. The combustion chamber according to claim 1, wherein the cross-section of each channel axially decreases in the downstream direction.

8. The combustion chamber according to claim 1, wherein the at least one channel for the flow of cooling air is delimited by a radially inner surface and a radially outer surface, in the form of a cylinder portion or cone portions, said radially inner and outer surfaces being coaxial.

9. The combustion chamber according to claim 5, wherein two adjacent channels are circumferentially separated by a connecting wall, said connecting wall having an upstream end and a downstream end, said upstream end being rounded.

10. The combustion chamber according to claim 1, wherein the cylindrical attachment part of the assembly is attached by brazing or welding to a cylindrical part of the bottom wall, formed in the radially inner periphery of the opening.

11. The combustion chamber according to claim 1, wherein the baffle extends radially in relation to a longitudinal axis of the opening.

12. The combustion chamber according to claim 1, wherein the bottom wall extends radially in relation to a longitudinal axis of the opening.

13. The combustion chamber according to claim 1, wherein a space is arranged axially between the baffle and the bottom wall and the at least one channel opens in the space.

14. The combustion chamber according to claim 1, wherein the air outlet is arranged to direct cooling air at an upstream side of the base of the baffle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view in axial cross-section of a prior art turbomachine;

(2) FIG. 2 is an axial cross-sectional view showing a combustion chamber of the turbomachine of FIG. 1;

(3) FIG. 3 is a schematic view of an injection system provided in the combustion chamber of FIG. 2;

(4) FIG. 4 is a view in axial cross-section of a portion of a combustion chamber according to one embodiment of the invention;

(5) FIG. 5 is a perspective view showing a part of the bottom of the chamber and a part of the assembly forming in particular the baffle and the mixing bowl, in accordance with the invention;

(6) FIG. 6 is a detailed view of FIG. 4; and

(7) FIG. 7 is a detailed view of FIG. 5.

DETAILED DESCRIPTION

(8) A combustion chamber 5 according to one embodiment is shown in FIGS. 4 to 7. This chamber includes a radially inner annular shell 11 and a radially outer annular shell 12, with respect to the X axis of the turbomachine, said shells 11, 12 being coaxial.

(9) Annular fairings 15 are mounted at the upstream ends of the shells 11, 12 and delimit an annular volume.

(10) The shells 11, 12 are connected at their upstream end by a radial annular wall at the bottom of the chamber 16. The bottom of the chamber 16 has Y-axis openings, evenly distributed over the circumference. In particular, the edge of each opening is delimited by a cylindrical attachment part 28. The cylindrical part 28 has a shoulder 29 at its upstream end (FIG. 6).

(11) An assembly 30 forming both a mixing bowl 22 and a baffle 23 protecting the bottom of the chamber 16, is mounted and attached in each opening of the bottom of the chamber 16.

(12) An air intake or injection device 21 is mounted upstream of the assembly 30.

(13) The device 21 has an annular Y axis and has, in the downstream direction, a part 31 being used to mount a sleeve 19, an upstream air intake or injection swirler 21a and a downstream air intake or injection swirler 21b.

(14) The upstream part 31 of the device 21 comprises a cylindrical part 32 and a radial part 33, a washer 34 being attached in the cylindrical part 32. The washer 34 is axially offset from the radial part 33 so as to form a groove used for mounting a flange 34a of the sleeve 19. The sleeve 19 also has a tapered part 35 surrounding the nose 20 of a fuel injection rod 18. Fuel injection is carried out along the Y axis.

(15) The swirlers 21a, 21b are separated from each other by an annular wall 26 which extends radially inward to form an inner annular deflection wall 27, also called a venturi, having an inner profile of convergent and then divergent shape, in the downstream direction.

(16) Each swirler 21a, 21b typically has an annular row of fins that are inclined to rotate the air flow and thus improve the atomization or vaporization of the fuel jet from the nose 20 of the fuel injection rod 18. In particular, some of this fuel streams in liquid form on the inner surface of the venturi 27 and is sheared by the swirling air at the downstream end of the venturi 27.

(17) The bowl 22 is formed by a tapered annular wall that widens in the downstream direction. Said tapered wall has holes 36 (FIGS. 4 and 5) enabling the passage of the cooling air from the internal volume delimited by the fairings 15 to the combustion chamber 5.

(18) The baffle 23 is formed at the radially outer downstream periphery of the bowl 22. In particular, the baffle 23 has a cylindrical axial part 25 extending in the upstream direction from the outer periphery of the bowl 22 and a part 24 extending radially outward from the downstream end of the cylindrical part 25. The peripheries of the radial part 24 are extended by rims 37 extending in the upstream direction and radially spaced from the corresponding shells.

(19) The cylindrical part 25 of the assembly 30 is mounted in the cylindrical part 28 of the bottom wall 16. The upstream end of the cylindrical part 25 of the assembly 30 axially abuts the shoulder 29. The cylindrical part 25 of the assembly 30 is attached by brazing or welding to the cylindrical part 28 of the chamber bottom 16, in particular at the corresponding cylindrical surfaces 38 (FIG. 6), or even also at the annular radial surface forming the shoulder 29.

(20) Channels 39 are formed in the cylindrical axial part 25 of the baffle 23, the channels 39 being evenly distributed over the circumference. The channels 39 are separated in pairs by axially extending connecting walls 40 (FIG. 7). Each channel 39 is delimited by a radially inner surface 41, a radially outer surface 42 and by the surfaces of the two corresponding adjacent connecting walls 40.

(21) The radially inner and outer surfaces 41, 42 are coaxial and cylindrical, for example.

(22) The upstream end 43 of each connecting wall 40 can be rounded to facilitate the introduction of the cooling air into the channels 39, thus limiting pressure drops. The term rounded can refer to a complex shape with a rounded portion, for example having a triangular end with a rounded top.

(23) The downstream end of each channel 39 opens out opposite the radially inner base part 44 of the radial part of the baffle 23 (FIG. 6), i. e. at the connecting area 44 between the radial part 24 of the baffle 23 and the downstream end of the axial part 25. This connection area 44 may have a fillet.

(24) Each channel 39 can have a cross-section with a radial and/or circumferential dimension between 15 and 35 mm.

(25) The assembly 30 can be made of a nickel- and/or cobalt-based super alloy. The assembly 30 can be produced using an additional manufacturing method, for instance using selective melting or selective powder sintering, with an electron beam or a laser beam.

(26) In operation, the cooling air from the high-pressure compressor enters the channels 39 and impacts the base 44 of the radial part 24 of the baffle 23 and then circulates in the space 45 axially provided between said radial part 24 and the bottom of the chamber 16 before reaching the combustion chamber 5 through the space 46 (FIG. 4) between the rims 37 and the shells 11, 12.

(27) This cooling air effectively cools the axial part 25 of the assembly 30 and the base 44 of the radial part 24, which are the most critical areas in terms of thermal stress. This avoids the appearance of seams or cracks in order to increase the service life of the assembly 30.