Combustion chamber with fences for directing cooling flow

1. A combustion chamber arrangement, comprising:

an annular outer wall; and

an annular inner wall spaced from the annular outer wall,

the annular inner wall comprising an upstream row of tiles and a downstream row of tiles, each row of tiles comprising a plurality of circumferentially arranged tiles, each tile in each row of tiles having an upstream end and a downstream end,

the downstream end of each tile in the upstream row of tiles having (i) a first rail extending from the downstream end of the tile towards and sealing with an inner surface of the annular outer wall and (ii) a lip extending in a downstream direction towards but spaced from the upstream ends of the tiles in the downstream row of tiles,

the upstream end of each tile in the downstream row of tiles having a second rail extending from the upstream end of the tile towards and sealing with an inner surface of the annular outer wall, an upstream region of at least one of the tiles in the downstream row of tiles having at least one of a dilution aperture and an igniter aperture,

the annular outer wall having at least one row of apertures to direct coolant onto outer surfaces of the lips at the downstream ends of the tiles in the upstream row of tiles, the at least one row of apertures being arranged to supply the coolant to a chamber defined between the inner surface of the annular outer wall, the first rails and the lips of the downstream ends of the tiles in the upstream row of tiles,

the downstream end of at least one of the tiles in the upstream row of tiles having a plurality of circumferentially spaced fences that extend in a downstream direction from the first rail and are spaced circumferentially from circumferentially spaced edges of the tile, each fence extending from the outer surface of the lip towards the inner surface of the annular outer wall, the at least one tile in the upstream row of tiles being arranged such that the at least one of the dilution aperture and the igniter aperture is positioned circumferentially between two circumferentially adjacent fences at the downstream end of the at least one tile in the upstream row of tiles, and

at least one of the apertures in the at least one row of apertures in the annular outer wall is arranged so that an axis of the at least one aperture intersects the lip to direct coolant onto the lip between two circumferentially adjacent fences.

2. The combustion chamber arrangement as claimed in claim 1 , wherein the at least one tile in the upstream row of tiles is arranged such that the dilution aperture or the igniter aperture is positioned circumferentially midway between two circumferentially adjacent fences at the downstream end of the tile in the upstream row of tiles.

3. The combustion chamber arrangement as claimed in claim 1 , wherein:

the upstream region of the at least one tile in the downstream row of tiles has at least the dilution aperture, and

the circumferential distance between two circumferentially adjacent fences in the upstream row of tiles is at least equal to the diameter of the dilution aperture.

4. The combustion chamber arrangement as claimed in claim 1 , wherein:

the upstream region of each of a plurality of the tiles in the downstream row of tiles has the dilution aperture or the igniter aperture, and

each one of the plurality of tiles in the upstream row of tiles is arranged such that the dilution aperture or the igniter aperture of a respective one of the plurality of tiles in the downstream row of tiles is positioned circumferentially between two circumferentially adjacent fences at the downstream end of the respective one of the plurality of tiles in the upstream row of tiles.

5. The combustion chamber arrangement as claimed in claim 4 , wherein:

the upstream region of each of the plurality of the tiles in the downstream row of tiles has the dilution aperture,

each fence at the downstream ends of the tiles in the upstream row of tiles is positioned circumferentially midway between two circumferentially adjacent dilution apertures at the upstream regions of the tiles in the downstream row of tiles, and

the number of fences at the downstream ends of the tiles in the upstream row of tiles is equal to the number of dilution apertures at the upstream regions of the tiles in an intermediate row of tiles.

6. The combustion chamber as claimed in claim 1 , wherein:

the upstream region of the at least one tile in the downstream row of tiles has at least the dilution aperture, and

the, or each, dilution aperture at the upstream region of a tile in the downstream row of tiles has at least three fences positioned immediately upstream thereof at the downstream end of a tile in the upstream row of tiles.

7. The combustion chamber arrangement as claimed in claim 6 , wherein the circumferential distance between a first fence and a last fence on the tile of the upstream row of tiles is at least equal to the diameter of the dilution aperture in the downstream row of tiles.

8. The combustion chamber arrangement as claimed in claim 7 , wherein:

the circumferential distance between the first and last fences on the tile of the upstream row of tiles is greater than the diameter of the dilution aperture in an intermediate row of tiles, and

the remaining fences are positioned at equal circumferential distances apart between the first and last fences.

9. The combustion chamber arrangement as claimed in claim 7 , wherein the circumferential midway point between the first and last fences is aligned circumferentially with the middle of the dilution aperture in the downstream row of tiles.

10. The combustion chamber arrangement as claimed in claim 1 , wherein a plurality of apertures in the at least one row of apertures in the annular outer wall are arranged to direct coolant onto the lip between two circumferentially adjacent fences.

11. The combustion chamber arrangement as claimed in claim 1 , wherein each fence extends from the outer surface of the lip towards the inner surface of the annular outer wall and contacts the inner surface of the annular outer wall.

12. The combustion chamber arrangement as claimed in claim 1 , wherein each fence extends in a downstream direction from the first rail, which extends the full length of the lip.

13. The combustion chamber arrangement as claimed in claim 1 , wherein the second rail at the upstream end of each tile in the downstream row of tiles extends in an upstream direction.

14. The combustion chamber arrangement as claimed in claim 1 , wherein the combustion chamber is an annular combustion chamber and the annular inner wall is spaced radially inwardly from the annular outer wall.

15. The combustion chamber arrangement as claimed in claim 1 , wherein the combustion chamber is a tubular combustion chamber and the annular inner wall is spaced radially inwardly from the annular outer wall.

16. The combustion chamber arrangement as claimed in claim 1 , wherein the combustion chamber is a gas turbine engine combustion chamber.

17. The combustion chamber arrangement as claimed in claim 1 , wherein the lip at the downstream end of each tile in the upstream row of tiles extends from a junction between the first rail at the downstream end of the tile and a main body of the tile.

18. The combustion chamber arrangement as claimed in claim 1 , wherein:

the upstream end of each tile in the upstream row of tiles has a third rail that extends from the upstream end of the tile towards and seals with the inner surface of the annular outer wall, and

each tile in the upstream row of tiles has fourth rails that extend axially along circumferentially spaced edges of the tile and that extend towards and seal against the inner surface of the annular outer wall to form a closed chamber between each tile and the annular outer wall.

19. The combustion chamber arrangement as claimed in claim 1 , wherein the downstream ends of the tiles in the upstream row of tiles are located upstream of the upstream ends of the tiles in the downstream row of tiles.