Device for guiding a stream of air entering a combustion chamber of a turbomachine

1. A device for guiding a stream of air entering a combustion chamber of a turbomachine, comprising:

a flow straightener comprising first and second coaxial shrouds between which substantially radial vanes extend; and

a diffuser disposed downstream of the flow straightener, the diffuser comprising first and second coaxial walls of revolution joined together by radial partitions,

wherein the first shroud of the flow straightener is formed as one with the first wall of revolution of the diffuser,

wherein the second shroud of the flow straightener is added and attached to the second wall of revolution of the diffuser, and

wherein the substantially radial vanes of the flow straightener are secured at a first end to the first shroud of the flow straightener and separated by a small clearance from the second shroud at a second end.

2. The device as claimed in claim 1 , wherein:

the first and second coaxial shrouds of the flow straightener comprise an inner shroud and an outer shroud, the outer shroud disposed at a radial distance from a common axis of the first and second coaxial shrouds greater than that of the inner shroud,

the first and second coaxial walls of revolution comprise an inner wall of revolution and an outer wall of revolution, the outer wall of revolution disposed at a radial distance from a common axis of the first and second coaxial walls of revolution greater than that of the inner wall of revolution,

the outer shroud and the outer wall of revolution are formed as one, and

the inner shroud is fixed to the inner wall of revolution.

3. The device as claimed in claim 2 , wherein the outer shroud is cast as one with the diffuser.

4. The device as claimed in claim 2 , wherein a downstream end of the inner shroud is welded to an upstream end of the inner wall of revolution.

5. The device as claimed in claim 2 , wherein the substantially radial vanes of the flow straightener are secured via radially outer ends to the outer shroud and are separated by a small radial clearance from the inner shroud.

6. The device as claimed in claim 2 , wherein the substantially radial vanes of the flow straightener are secured via their radially inner ends to the inner shroud and are separated by a small radial clearance from the outer shroud.

7. The device as claimed in claim 2 , wherein the inner shroud comprises an axial annular rim engaged radially inside the inner wall of revolution.

8. The device as claimed in claim 1 , wherein:

one of the first or second coaxial shrouds of the flow straightener comprises at least one slot, and at least one vane end of the substantially radial vanes is fixed to the at least one slot.

9. The device as claimed in claim 1 , wherein the substantially radial vanes are formed as one with one of the first or second coaxial shrouds of the flow straightener.

10. The device as claimed in claim 1 , wherein the clearance between the substantially radial vanes and one of the first and second coaxial shrouds of the flow straightener ranges between about 0.1 and 0.5 mm in operation.

11. A turbomachine, which comprises a device as claimed in claim 1 .

12. A diffuser for a turbomachine, comprising:

a first wall of revolution;

a second wall of revolution joined to the first wall of revolution by at least one radial partition; and

a first frustoconical web attached to the first wall of revolution,

wherein a first shroud of a flow straightener is formed as one with the first wall of revolution,

wherein the second wall of revolution is arranged coaxially with the first wall of revolution,

wherein the first shroud of the flow straightener extends axially in the upstream direction beyond the second wall of revolution, and

wherein the first wall of revolution extends axially downstream from an attachment point of the first frustoconical web to the first wall of revolution.

13. The diffuser as claimed in claim 12 , wherein the first shroud of the flow straightener comprises a plurality of radial through-slots uniformly distributed about the axis of the diffuser.

14. The diffuser as claimed in claim 13 , wherein the number of radial through-slots is more than 100.

15. The diffuser as claimed in claim 12 , wherein the first shroud of the flow straightener is formed as one with radial vanes which are uniformly distributed about the axis of the diffuser.

16. The diffuser as claimed in claim 15 , wherein the number of radial vanes is more than 100.

17. The diffuser for a turbomachine of claim 12 , wherein the first frustoconical web diverges radially outward in the upstream direction.

18. The diffuser for a turbomachine of claim 12 , wherein the first frustoconical web converges radially inward in the downstream direction.

19. The diffuser for a turbomachine of claim 12 , further comprising a second frustoconical web attached to the second wall of revolution.

20. The diffuser for a turbomachine of claim 12 , wherein the first frustoconical web comprises an outer annular flange.