Sector for the assembly of a stage of a turbine and corresponding manufacturing method

1. A sector for the assembly of a stage of a turbine comprising:

a central portion;

a peripheral portion;

a plurality of blades attached between the central portion and the peripheral portion;

a first side and a second side opposite to each other, the first side configured to join with a second side of another sector, the first side provided with a first connecting portion and the second side provided with a second connecting portion configured to mate with a first connecting portion of a first side of another sector,

wherein at least one of the blades has an opening on a respective external surface, said blade having an internal cavity in fluid communication with said opening, the sector having a channel in fluid communication with the internal cavity, said channel being located inside said central portion.

2. A sector according to claim 1 , wherein the first connecting portion and the second connecting portion are located on the central portion.

3. A sector according to claim 1 , wherein the first side and the second side define each a respective interface plane, each interface plane being also defined by a radial direction and by a central axis of said sector.

4. A sector according to claim 3 , wherein the said second connecting portion has a protrusion extending from the interface plane of the second side, the first connecting portion having a recess extending inward from the interface plane of the first side.

5. A sector according to claim 1 , wherein the first connecting portion comprises a groove surrounding at least in part said channel; the second connecting portion comprising a tongue surrounding at least in part said channel, said tongue being configured to be inserted into the groove of another sector.

6. A sector according to claim 1 , wherein the second connecting portion has a socket, the first connecting portion having a key configured to be inserted into the socket to lock said first and second connecting portions.

7. A sector according to claim 6 , wherein said key has a complementary shape with respect to said socket.

8. A sector according to claim 6 , wherein the key and the socket are located on a radially outward wall of a channel.

9. A sector according to claim 1 , wherein the central and peripheral portions are built as a single block of material.

10. A sector according to claim 5 , further comprising a further groove placed on the first side; a further tongue placed on the second side.

11. A sector according to claim 10 , wherein said further groove and said further tongue are placed on the peripheral portion.

12. A sector according to claim 10 , also comprising holes placed on the first side and the second side on the peripheral portion, said holes being each configured to be aligned with holes of another sector to receive a connection element.

13. A method for manufacturing a turbine comprising a plurality of sectors, each sector comprising a central portion, a peripheral portion, a plurality of blades attached between the central portion and the peripheral portion, a first side and a second side opposite each other, the first side configured to join with a second side of another sector, the first side having a first connecting portion and the second side having a second connecting portion, the method comprising:

joining the plurality of sectors to define two half-stages, said joining comprising mating the second connecting portion on the second side of at least one sector to the first connecting portion on the first side of an adjacent sector; and

joining said half-stages to assemble a stage of the turbine,

wherein the mating step comprises inserting a tongue on said second connecting portion into a groove on said first connecting portion, and placing a sealing material between the tongue and the groove to join two channels of the respective sectors in a fluid-tight manner.