Combustor wall cooling channel formed by additive manufacturing

1. A cooled wall for lining a combustor of a gas turbine comprising:

an annular outer wall extending axially along a centerline intersecting the geometric center of the gas turbine, wherein the annular outer wall defines a radial passage, and wherein the radial passage extends through the annular outer wall;

a first inner wall spaced radially inward from the annular outer wall with respect to the centerline;

a first connecting wall joining the first inner wall to the annular outer wall, wherein the annular outer wall, the first inner wall, and the first connecting wall define an axial channel therebetween that is in fluid communication with the radial passage;

a second inner wall spaced radially inward from the annular outer wall; and

a second connecting wall joining the second inner wall to the annular outer wall, wherein the second inner wall is axially spaced from the first inner wall to define a circumferentially-extending opening between a first end face of the first inner wall and a second end face of the second inner wall;

wherein:

the annular outer wall, the first and second inner walls, and the first and second connecting walls form a monolithic body;

the annular outer wall is formed from a metallic material;

the first and second inner walls are formed from a ceramic material; and

the first and second connecting walls have a functionally graded distribution of the metallic and ceramic materials between the annular outer wall and the first and second inner walls, respectively.

2. The cooled wall of claim 1 , wherein the first end face and the second end face are angled with respect to the centerline.

3. The cooled wall of claim 1 , wherein one inner wall of the first and second inner walls defines a hole, and wherein the hole extends through the one inner wall to place the axial channel in fluid communication with a surface of the one inner wall, and wherein the hole is configured to film-cool the one inner wall.

4. The cooled wall of claim 1 , wherein the first inner wall extends a first distance from the first connecting wall towards the second inner wall and a second distance substantially equal and opposite the first distance.

5. The cooled wall of claim 1 , wherein the first inner wall extends from the first connecting wall towards the second inner wall.

6. The cooled wall of claim 1 , wherein the annular outer wall comprises:

a first segment, wherein the first connecting wall joins the first inner wall to the first segment; and

a second segment positioned radially outward and axially spaced from the first segment so as to define a stepped annular shape; and

wherein

the second connecting wall joins the second inner wall to the second segment of the annular outer wall; and

the second inner wall is spaced radially outward from the first inner wall to define an annular opening between a radially outer surface of the first inner wall and a radially inner surface of the second inner wall.

7. The cooled wall of claim 6 , wherein the first connecting wall is axially spaced from the second connecting wall a first distance, and wherein the first inner wall extends from the first connecting wall towards the second inner wall a second distance that is greater than the first distance.

8. The cooled wall of claim 6 , wherein the first segment and the second inner wall form a contiguous surface such that the axial channel is aligned with the radially inner surface of the second inner wall.

9. The cooled wall of claim 1 , wherein the first and second ends are curved in an axial direction.

10. A combustor section of a gas turbine engine comprising:

a plurality of annular wall segments defining a cavity for combustion having a centerline extending axially through a geometric center of the cavity and defining a plurality of radial passages, wherein each of the plurality of radial passages extends through one of the plurality of annular wall segments;

a plurality of inner wall segments spaced radially inward from the annular wall segments so as to define axial channels between each of the inner wall segments and one of the plurality of annular wall segments, wherein the axial channel is in fluid communication with at least one of the radial passages, and wherein the inner wall segments are configured to define circumferentially-extending openings between opposing end faces of adjacent inner wall segments;

a plurality of connecting walls, each connecting wall extending from one of the plurality of annular wall segments to one of the plurality of inner wall segments;

wherein:

the annular outer wall segments are formed from a metallic material;

the inner wall segments are formed from a ceramic material; and

the connecting walls have a functionally graded distribution of the metallic and ceramic materials between respective annular outer wall and inner wall segments.

11. The combustor section of claim 10 , wherein the openings are configured to direct cooling air along the inner wall segments, and wherein the inner wall segments further comprise:

a first subset of inner wall segments defining a first subset of openings; and

a second subset of inner wall segments defining a second subset of openings, wherein the second subset of openings is configured to direct more cooling air per unit area of the second subset of inner wall segments than the first subset of openings is configured to direct on to the first subset of inner wall segments.

12. A method of manufacturing a cooled wall for a combustor of a gas turbine engine; the method comprising:

a.) providing a three-dimensional computer model of the cooled wall;

b.) depositing a powdered material to form a uniform thickness layer on a substrate or a previously deposited layer;

c.) using a laser or an electron beam to melt or sinter the powdered material to form a cross-section of the cooled wall defined by the three-dimensional computer model; and

d.) repeating steps b-c to form a cooled wall, wherein the cooled wall comprises:

an annular outer wall extending axially along a centerline intersecting the geometric center of the gas turbine, wherein the annular outer wall defines a radial passage, and wherein the radial passage extends through the annular outer wall;

a first inner wall spaced radially inward from the annular outer wall with respect to the centerline;

a first connecting wall joining the first inner wall to the annular outer wall, wherein the annular outer wall, the first inner wall, and the first connecting wall define an axial channel therebetween that is in fluid communication with the radial passage;

a second inner wall spaced radially inward from the annular outer wall; and

a second connecting wall joining the second inner wall to the annular outer wall, wherein the second inner wall is axially spaced from the first inner wall to define a circumferentially-extending opening between a first end face of the first inner wall and a second end face of the second inner wall:

wherein:

the annular outer wall, the first and second inner walls, and the first and second connecting walls form a monolithic body;

the annular outer wall is formed from a metallic material;

the first and second inner walls are formed from a ceramic material; and

the first and second connecting walls have a functionally graded distribution of the metallic and ceramic materials between the annular outer wall and the first and second inner walls, respectively.

13. The method of claim 12 , wherein the functionally graded distribution of the ceramic material linearly decreases along the first connecting wall towards the annular outer wall.