Assembly for a turbomachine combustion chamber

Abstract

An assembly for a combustion chamber of a turbomachine. The assembly comprises an annular shell extending along a longitudinal axis, the shell having an inner wall intended to be turned towards a furnace of the combustion chamber and an outer wall opposite the inner wall and a projecting element extending radially from an area of the outer wall. The shell has at least one deflector projecting from the outer wall and located downstream of the projecting element with respect to a direction of gas flow along the outer wall, oriented along the longitudinal axis. The deflector extends circumferentially. Perforations are provided axially between the projecting element and the or each deflector.

Claims

1. An assembly for a combustion chamber of a turbomachine, the assembly comprising: an annular shell extending along a longitudinal axis, said shell comprising an inner wall configured to be turned towards a furnace of the combustion chamber and an outer wall opposite the inner wall; a projecting element extending radially from an area of the outer wall; and a plate attached to the shell and forming a part of said shell, the plate comprising: at least one plurality of deflectors configured as inclined walls integral with and projecting from the outer wall and connected thereto by respective rounded connection areas configured as fillets, the at least one plurality of deflectors located downstream of the projecting element with respect to a direction of gas flow along the outer wall, oriented along the longitudinal axis, wherein each deflector of the at least one plurality of deflectors extends circumferentially, is axially offset from other deflectors, and perforations arranged axially between the projecting element and each of the at least one plurality of deflectors, axially between the at least one plurality of deflectors and at the respective fillet, and opening at the inner wall and the outer wall.

2. The assembly according to claim 1, wherein each of the at least one plurality of deflectors has a general shape of a curve.

3. The assembly according to claim 1, wherein at least one deflector of the at least one plurality of deflectors extends circumferentially with respect to the projecting element on either side of the projecting element.

4. The assembly according to claim 1, wherein at least some of the perforations are located in the vicinity of the at least one plurality of deflectors.

5. The assembly according to claim 1, wherein at least one deflector of the at least one plurality of deflectors is inclined axially in the upstream direction with respect to the outer wall.

6. The assembly according to claim 2, wherein the distance between the outer end of each deflector of the at least one plurality of deflectors and the outer wall of the shell gradually increases in the downstream direction.

7. The assembly according to claim 1, wherein the projecting element is mounted or formed on the plate.

8. The assembly according to claim 1, wherein the projecting element has means for guiding a spark plug.

9. A turbomachine for an aircraft, the turbomachine comprising the assembly according to claim 1.

10. An assembly for a combustion chamber of a turbomachine, the assembly comprising: an annular shell extending along a longitudinal axis, said annular shell comprising an inner wall intended to be turned towards a furnace of the combustion chamber and an outer wall opposite the inner wall; and a projecting element extending radially from an area of the outer wall, wherein the annular shell comprises a plurality of deflectors projecting from the outer wall and located downstream of the projecting element with respect to a direction of gas flow along the outer wall, oriented along the longitudinal axis, the plurality of deflectors being arranged concentrically around the projecting element, perforations being provided in the shell, axially between the projecting element and each of the plurality of deflectors, and axially between the plurality of deflectors, with the perforations opening at the inner wall and the outer wall, and wherein the plurality of deflectors has a last deflector arranged furthest from the projecting element, and all deflectors of the plurality of deflectors other than the last deflector are arranged between the last deflector and the projecting element.

11. The assembly according to claim 1, wherein the at least one of the plurality of deflectors are arranged concentrically around the projecting element, the at least one of the plurality of deflectors has a last deflector arranged furthest from the projecting element, and all deflectors of the at least one of the plurality of deflectors other than the last deflector are arranged between the last deflector and the projecting element.

12. The assembly according to claim 10, wherein the plurality of deflectors are integral with the outer wall.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is an axial cross-sectional view of a combustion chamber of the prior art,

(2) FIG. 2 is an axial cross-sectional view of the spark plug guide means and a part of the outer shell of the combustion chamber of FIG. 1;

(3) FIG. 3 is a top view of the outer shell, illustrating the cracks or clinks that may appear in the case of the prior art;

(4) FIG. 4 is a perspective view of a part of an assembly according to one embodiment of the invention, as seen in the upstream direction;

(5) FIG. 5 is a perspective view of a part of an assembly according to one embodiment of the invention, as seen in the downstream direction;

(6) FIG. 6 is a detailed perspective view showing specifically the deflectors;

(7) FIG. 7 is a detailed schematic view illustrating an alternative embodiment of the invention;

(8) FIG. 8 is a perspective view showing the plate and a part of the guide means according to one embodiment of the invention;

(9) FIG. 9 is a perspective view showing the plate and a part of the guide means according to another embodiment of the invention;

(10) FIG. 10 shows the guide means intended to be mounted on the plate of FIG. 9.

DETAILED DESCRIPTION

(11) FIGS. 4 to 6 show a part of an assembly for a combustion chamber 1 for a turbomachine according to one embodiment of the invention. The assembly includes an annular shell, for example the outer shell 3 extending along a longitudinal axis 7. The shell 3 has an inner wall 17 intended to face a firebox in the combustion chamber 1 and an outer wall 25 opposite the inner wall 17.

(12) The shell 3 also has an opening for mounting and attaching a plate 30.

(13) The plate 30 has, seen radially from the outside towards the inside, an upstream area 31 having a semicircular shape and a downstream area 32 having a generally square or rectangular shape with rounded corners.

(14) The plate 30 has a central opening 33 intended for a spark plug 12 to pass therethrough. Said opening 33 is circular in shape. In addition, the plate 30 has curved deflectors 34, for example in an arc of a circle, so that they generally conform to the shape of the opening 33, and are located downstream of the opening 33. Here, the plate 30 has six deflectors 34, for example evenly spaced axially from each other. The deflectors 34 can be regularly spaced in a homogeneous thermal environment, the spacing may vary if the area covered is large. The axial distance between the deflectors 34 is for example between 1 and 5 mm.

(15) The deflectors 34 are centred circumferentially with respect to a median plane 35 passing through the axis 7 of the shell and the axis 37 substantially perpendicular to the elongation axis of the chamber of the opening of the plate 30. The plane 35 is also perpendicular to the plate 30.

(16) The deflectors 34 extend circumferentially over an angular range between 40 and 180°, said angular range being defined with respect to the axis of the chimney 19.

(17) It should be noted that for each deflector 34, the deflector 34 located upstream extends over a smaller angular range than the deflector 34 located directly downstream. In other words, the deflectors 34 located upstream are shorter than the deflectors 34 located downstream.

(18) As it is best seen in FIG. 6, each deflector 34 has an inclined wall 38 with respect to the axial direction and the radial direction. In particular, the angle of the inclined wall 38 in the upstream direction with respect to the radially outer surface of the shell 3 is between 10 and 80°. Said inclined wall 38 of each deflector 34 is connected to the plate 30 by a rounded connection area 39 forming a fillet 40. Perforations 41 are provided in the plate 30 at the fillet 40 of each deflector 34. For example, the perforations 41 are evenly distributed along each deflector 34. The plate 30 has, for each deflector 34, a number of perforations 41 between 10 and 50. Each perforation 41 extends at an angle α between 10 and 60°, for example about 30° with respect to the axial direction. For example, the perforations 41 have a diameter between 0.2 and 1 mm, preferably between 0.4 and 0.6 mm.

(19) In the embodiment shown in FIGS. 4 to 6 in particular, the deflectors 34, for example, all extend radially over the same distance.

(20) According to an alternative embodiment illustrated in FIG. 7, the radial extension distance of the deflectors 34 increases gradually in the downstream direction.

(21) The plate 30 is attached to the shell 3 by welding or brazing, for example.

(22) Means 18 for guiding the spark plug 12 are mounted on the plate 30, at the opening 33 (FIG. 9). The guide means 18 comprises a tubular chimney 19 having a first end 42 attached to the plate 30, for example by welding, and surround the opening 33 of the plate 30, and an opposite second end 43, with a larger diameter than the first end 42, and define an annular groove 21. The chimney 12 and the plate 30 can, as an alternative, be formed in one single piece. The chimney 19 may have holes 44 oriented perpendicularly to axis 45 of the chimney 19 and distributed over the circumference of the chimney 19.

(23) An annular guide 20 is mounted on the chimney 19. The guide 20 has a frustoconical wall 46 widening opposite the shell 3 and an annular flange 47 mounted with radial and axial clearance in the groove 21 of the chimney 19, as known per se. The spark plug 12 is intended to be engaged into the guide 20 and the chimney 19, the inner end 15 of the spark plug 12 passing through the opening 33 of the plate 30, until it is substantially flush with the inner surface 17 of the shell 3.

(24) The shell 3 and the plate 30 have perforations 24, also called multi-perforations 24 because of their large number. The shell 3 also has holes for the passage of the so-called primary airstream 22 and holes for the passage of the secondary airstream 23. The secondary airstream holes 23 are located axially downstream of the primary airstream holes 22.

(25) The multi-perforations 24 of the shell 3 and/or the plate 30, can have a diameter between 0.2 and 1 mm, preferably between 0.4 and 0.6 mm. The multi-perforations 24 can be performed by laser drilling.

(26) The perforations 41 and/or the multi-perforations 24 can be inclined with respect to the outer wall 25 of the shell 3, at an angle α between 10 and 50°, for example around 30°. The perforations 41 and/or the multi-perforations 24 may be located at least partially in a plane passing through the axis 7 of the shell. Alternatively, at least a part of the perforations 41 and/or the multi-perforations 24 may be formed in one or more plane(s) forming an angle with the axis 7 of the shell, for example an angle between 30 and 90° inclusive. Such perforations 41 or multi-perforations 24 are said giratory.

(27) The primary airstream holes 22 can have a diameter between 5 and 15 mm and the secondary airstream holes 23 can have a diameter between 4 and 12 mm.

(28) The multi-perforations 24 of the plate 30 can be made after attaching the plate 30 to the rest of the shell 3.

(29) The plate 30 and the shell 3 can be formed in one single piece. In general and structurally, it can be considered that the plate 30 is part of the shell 3.

(30) FIGS. 9 and 10 illustrate another embodiment, which differs from the one shown above in that the plate 30 has an annular flange 48 extending radially outward and surrounding the opening 33 of the plate 30. The second end 43 of the chimney 19 forms a radial annular shoulder, resting on the outer end of the flange 48. The flange 48 is made in one piece with the plate 30.

(31) The plate 30 can be produced by an additive manufacturing process, such as melting or selective sintering of powders using a laser or an electron beam, for example. The plate 30 is for example made For example, the shell 3 is made of a cobalt-based alloy, such as a Hastelloy or HA188 alloy.

(32) The shell can be a radially outer shell, as described above, or a radially inner shell 4 of a turbomachine combustion chamber.

(33) The deflectors 34 downstream of the guide means 18 make it possible to bring a part of the air flow 49 (represented in FIG. 4) diverted by the projecting element 18 towards the area 26 less favoured by the circulation of the air flow 49. Air then enters the combustion chamber 1 through the perforations 24, 41. This significantly improves the cooling of the shell 3, 4 in the area 26 directly downstream of the projecting element 18. It should be noted that all or part of the deflectors 34 extend circumferentially on either side of the chimney 19 so as to capture and guide a larger part of the air flow 49 to the area 26 concerned.

(34) It should be noted that the invention is applicable to any projecting element 18 of the shell 3, 4, and is not limited to the case of guiding means 18 of a spark plug 12.