Turbine wheel for turbomachine and the assembly method for such a wheel

1. A turbine wheel for a turbomachine comprising:

a turbine disk and several blade segments installed on the turbine disk, each blade segment comprising a root and at least one blade fixed to the root, the turbine disk comprising an upstream rib and a downstream rib each extending approximately in the annular direction around a longitudinal principal axis of the wheel and radially as far as a radial end of the disk, each blade segment installed on the turbine disk configured to be retained by the turbine disk in an external radial direction using upstream engagement means forming part of the root and configured to cooperate with complementary upstream engagement means forming an external radial end of the upstream rib, and downstream engagement means also forming part of the root and configured to cooperate with complementary downstream engagement means forming an external radial end of the downstream rib, the upstream rib and downstream rib of the turbine disk being configured to be moved from a separated engagement position to a close position, and vice versa, so that each blade segment is configured to be assembled on the turbine disks,

wherein at least one of the upstream rib and the downstream rib is elastic such that the at least one rib is configured to be moved from the separated position to the close position and from the close position to the separated position by respectively applying a pressure on the at least one rib, and releasing the applied pressure.

2. The turbine wheel according to claim 1 , wherein each of the upstream rib and downstream rib of the turbine disk is elastic.

3. The turbine wheel according to claim 1 , wherein the complementary upstream and downstream engagement means extend in an annular arrangement around a main longitudinal axis of the wheel, and the upstream and downstream engagement means of each root of the blades segment are made so that each forms an annular portion of the same axis, extending circumferentially around the entire root of the blade segment.

4. The turbine wheel according to claim 1 , wherein each blade segment comprises holding means for maintaining permanent cooperation between the upstream and downstream engagement means of the blade segment installed on the turbine disk, and the corresponding complementary upstream and downstream engagement means of this turbine disk when they cooperate with the turbine disk.

5. A turbine wheel according to claim 4 , wherein for each blade segment, the holding means comprise at least one flexible strip forming part of the root and for which a free end is designed to bear on the turbine disk.

6. The turbine wheel according to claim 1 , wherein the upstream rib and the downstream rib of the turbine disk define an annular space between them arranged around the main longitudinal axis of the wheel, the annular space communicating with cooling passages provided on the roots of the blade segments.

7. The turbine wheel according to claim 6 , wherein the upstream rib of the turbine disk has at least one injection hole passing through it and opening up inside the annular space, each injection hole being configured to cooperate with a cooling air injector of the turbomachine.

8. The turbine wheel according to claim 1 , wherein each blade segment of the wheel comprises at least two blades fixed to the root.

9. The turbine wheel according to claim 1 , wherein the disk is single-piece.

10. The turbine wheel according to claim 1 , wherein the upstream rib and downstream rib, in an undeformed state, are farther from each other than when in a deformed state.

11. A turbine wheel for a turbomachine comprising:

a turbine disk and several blade segments installed on the turbine disk, each blade segment comprising a root and at least one blade fixed to the root, the turbine disk comprising an upstream rib and a downstream rib each extending approximately in the annular direction around a longitudinal principal axis of the wheel and radially as far as a radial end of the disk, each blade segment installed on the turbine disk configured to be retained by the turbine disk in an external radial direction using upstream engagement means forming part of the root and configured to cooperate with complementary upstream engagement means forming an external radial end of the upstream rib, and downstream engagement means also forming part of the root and configured to cooperate with complementary downstream engagement means forming an external radial end of the downstream rib, the upstream rib and downstream rib of the turbine disk being configured to be moved from a separated engagement position to a close position, and vice versa, so that each blade segment is configured to be assembled on the turbine disk,

wherein at least one of the upstream rib and the downstream rib is elastic such that the at least one rib is configured to be moved from the separated position to the close position and from the close position to the separated position by respectively applying a pressure on the at least one rib, and releasing the applied pressure, and

wherein the complementary upstream and downstream engagement means, and the upstream and downstream engagement means of the root of each blade segment have a hook-shaped longitudinal section.

12. The turbine wheel according to claim 11 , wherein the complementary upstream engagement means have a hook-shaped longitudinal section projecting in the upstream direction and defining an engagement opening oriented approximately in the inwards radial direction into the wheel,

the upstream engagement means have a hook-shaped longitudinal section projecting in the downstream direction and defining an engagement opening oriented approximately radially outwards from the wheel, the complementary downstream engagement means have a hook-shaped longitudinal section projecting towards the downstream direction and defining an engagement opening oriented in approximately the inwards radial direction of the wheel, and

the downstream engagement means have a hook-shaped longitudinal section projecting in the upstream direction and defining an engagement opening oriented approximately in the outwards radial direction from the wheel.

13. The turbine wheel according to claim 11 , wherein each of the upstream rib and downstream rib of the turbine disk is elastic.

14. The turbine wheel according to claim 11 , wherein the complementary upstream and downstream engagement means extend in an annular arrangement around a main longitudinal axis of the wheel, and the upstream and downstream engagement means of each root of the blades segment are made so that each forms an annular portion of the same axis, extending circumferentially around the entire root of the blade segment.

15. The turbine wheel according to claim 11 , wherein each blade segment comprises holding means for maintaining permanent cooperation between the upstream and downstream engagement means of the blade segment installed on the turbine disk, and the corresponding complementary upstream and downstream engagement means of this turbine disk when they cooperate with the turbine disk.

16. A turbine wheel according to claim 15 , wherein for each blade segment, the holding means comprise at least one flexible strip forming part of the root and for which a free end is designed to bear on the turbine disk.

17. The turbine wheel according to claim 11 , wherein the upstream rib and the downstream rib of the turbine disk define an annular space between them arranged around the main longitudinal axis of the wheel, the annular space communicating with cooling passages provided on the roots of the blade segments.

18. The turbine wheel according to claim 17 , wherein the upstream rib of the turbine disk has at least one injection hole passing through it and opening up inside the annular space, each injection hole being configured to cooperate with a cooling air injector of the turbomachine.

19. The turbine wheel according to claim 11 , wherein each blade segment of the wheel comprises at least two blades fixed to the root.

20. The turbine wheel according to claim 11 , wherein the disk is single-piece.

21. Method for installing a turbine wheel according to any one of the previous claims, comprising the following successive steps of:

bringing the upstream rib and the downstream rib of the turbine disk into the close position;

positioning each blade segment with respect to the turbine disk such that when the upstream rib and the downstream rib of the turbine disk are once again brought into their separated engagement position, the upstream and downstream engagement means of the root of each blade segment engage with the complementary upstream and downstream engagement means of the turbine disk; and

bringing the upstream rib and the downstream rib of the turbine disk into their separated engagement position,

the steps including bringing the upstream rib and the downstream rib of the turbine disk into the close position and bringing the upstream rib and the downstream rib of the turbine disk into their separated engagement position being made by applying pressure on the upstream rib and the downstream rib using an appropriate tool, and releasing the applied pressure, respectively.

22. A turbine comprising:

a turbine disk and several blade segments installed on the turbine disk, each blade segment including a root and at least one blade fixed to the root, the turbine disk including an upstream rib and a downstream rib each extending approximately in the annular direction around a longitudinal principal axis of the wheel and radially as far as a radial end of the disk, each blade segment installed on the turbine disk configured to be retained by the turbine disk in an external radial direction using upstream engagement means forming part of the root and configured to cooperate with complementary upstream engagement means forming an external radial end of the upstream rib, and downstream engagement means also forming part of the root and configured to cooperate with complementary downstream engagement means forming an external radial end of the downstream rib, the upstream rib and downstream rib of the turbine disk being configured to be moved from a separated engagement position to a close position, and vice versa, so that each blade segment is configured to be assembled on the turbine disk,

wherein at least one of the upstream rib and the downstream rib is elastic such that the at least one rib is configured to be moved from the separated position to the close position and from the close position to the separated position by respectively applying a pressure on the at least one rib, and releasing the applied pressure.

23. A turbomachine comprising:

a turbine disk and several blade segments installed on the turbine disk, each blade segment including a root and at least one blade fixed to the root, the turbine disk including an upstream rib and a downstream rib each extending approximately in the annular direction around a longitudinal principal axis of the wheel and radially as far as a radial end of the disk, each blade segment installed on the turbine disk configured to be retained by the turbine disk in an external radial direction using upstream engagement means forming part of the root and configured to cooperate with complementary upstream engagement means forming an external radial end of the upstream rib, and downstream engagement means also forming part of the root and configured to cooperate with complementary downstream engagement means forming an external radial end of the downstream rib, the upstream rib and downstream rib of the turbine disk being configured to be moved from a separated engagement position to a close position, and vice versa, so that each blade segment is configured to be assembled on the turbine disk,

wherein at least one of the upstream rib and the downstream rib is elastic such that the at least one rib is configured to be moved from the separated position to the close position and from the close position to the separated position by respectively applying a pressure on the at least one rib, and releasing the applied pressure.