Transition channel between two turbine stages

1. A transition channel between a first turbine section and a second turbine section for a gas turbine engine, comprising:

a first radially external annular wall including ring sector elements housed inside an annular ring and orifices which inject a fluid into the channel in order to re-energize a boundary layer of the channel;

a second radially internal annular wall; and

a fluid supply device arranged between a space outside the ring and said injection orifices,

wherein an upstream end of the ring presses against a flange of a casing of the first turbine section via a seal and a downstream end of the ring is held by a tongue and groove fastener attached to the casing of the first turbine section, and

wherein the first wall includes an axial flange which cooperates with a groove in a bearing surface disposed on the ring between the upstream end and the downstream end of the ring.

2. The transition channel as claimed in claim 1 , wherein the supply device includes openings arranged in the annular ring, cavities arranged in the ring sectors forming the first wall and communicating with the injection orifices, and an annular channel, delimited by annular seals, arranged between the openings and the cavities and placing them in communication.

3. The transition channel as claimed in claim 1 , wherein the orifices for injecting fluid into the ring sector elements are obtained by machining the ring sectors.

4. The transition channel as claimed in claim 1 , wherein the fluid injection orifices are defined between openings machined in the ring sectors forming the first wall and guide elements fitted to said sectors.

5. The transition channel as claimed in claim 1 , wherein the injection orifices are arranged in order to impart a tangential speed component, in the plane transversal to the axis of the engine, to the fluid.

6. A gas turbine engine comprising:

a first turbine section and a second turbine section connected by a transition channel as claimed in claim 1 ,

wherein the ring arranges a fluid distribution cavity with a turbine casing element, said casing element including a fluid supply orifice communicating with a bleed zone upstream of the transition channel.

7. The gas turbine engine as claimed in claim 6 , wherein said bleed zone upstream of the transition channel is carried out at a compressor of the engine, and bled air from the bleed zone forms a cold film protecting the first wall.

8. The gas turbine engine as claimed in claim 7 wherein the ring sectors, forming the first radially external annular wall of the transition channel, are fitted to elements forming a distributor at an entrance to the second turbine section.

9. The gas turbine engine as claimed in claim 8 , wherein said ring sectors forming the first wall constitute monobloc parts with the elements of the distributor.

10. The transition channel as claimed in claim 1 , wherein a downstream end of the first wall includes a tongue connection which abuts a groove disposed in a distributor of the second turbine section.

11. The transition channel as claimed in claim 1 , wherein an upstream end of the first wall presses against a sealing ring via a seal.

12. A transition channel between a first turbine section and a second turbine section for a gas turbine engine, comprising:

a first radially external annular wall including ring sector elements housed inside an annular ring and orifices which inject a fluid into the channel in order to re-energize a boundary layer of the channel;

a second radially internal annular wall; and

a fluid supply device arranged between a space outside the ring and said injection orifices,

wherein the supply device includes openings arranged in the annular ring, cavities arranged in the ring sectors forming the first wall and communicating with the injection orifices, and connecting tubes fitted between said openings and said cavities.