Air tube

1. An air tube for a gas turbine engine including a combustor with an outer liner, the air tube comprising:

an inner tube circumferentially extending around an air tube axis longitudinal to the air tube, having

an outer surface,

an inner tube inlet, and

an inner tube outlet disposed opposite of the inner tube inlet, the inner tube outlet in fluid communication with the inner tube inlet;

an outer plate configured to be connected to the outer liner of the combustor;

an outer tube disposed outward of the inner tube and having

an inner surface;

an outer tube inlet proximate the inner tube inlet;

an outer tube outlet opposite the outer tube inlet, the outer tube outlet in fluid communication with the outer tube inlet; and

a plurality of fins disposed along the inner surface of the outer tube, extending from proximate the outer tube outlet towards the outer tube inlet and not contacting the inner tube;

a strut extending from proximate the inner tube inlet towards the inner tube outlet on the outer surface of the inner tube and connected to the inner surface of the outer tube; and

wherein the plurality of fins are disposed downstream of the strut, in which downstream is relative to an air flow direction within the air tube, and the plurality of fins vary in length with respect to the air tube axis.

2. The air tube of claim 1 , further comprising an igniter tube extending through and from the outer plate.

3. The air tube of claim 1 , wherein the outer tube inlet and the outer tube outlet are disposed axially between the inner tube inlet and the inner tube outlet with respect to the air tube axis.

4. The air tube of claim 1 , wherein the plurality of fins are shaped to be wider adjacent the outer tube than inward of the outer tube.

5. The air tube of claim 1 , wherein the inner tube inlet is larger than the inner tube outlet.

6. The air tube of claim 1 , wherein the air tube is made of metal and the outer plate has a surface texture created by an additive manufacturing process.

7. An air tube for a gas turbine engine, the air tube comprising:

an outer cylindrical tube having a plurality of fins;

an inner cylindrical tube disposed within the outer tube, having an inner tube inlet and an inner tube outlet opposite the inner tube inlet;

a plurality of struts each extending from proximate the inner tube inlet towards the inner tube outlet and extending from the inner cylindrical tube to the outer cylindrical tube; and

an outer plate disposed outward of and circumferentially connected to the outer cylindrical tube, the outer plate formed to be connected to an outer liner of a combustor of the gas turbine engine,

wherein the plurality of fins are disposed downstream of the plurality of struts, in which downstream is relative to an air flow direction within the air tube, and

wherein the plurality of fins are disposed along an inner surface of the outer cylindrical tube, extending radially inwards toward the inner cylindrical tube and not contacting an outer surface of the inner cylindrical tube, and the plurality of fins vary in length with respect to an air tube axis.

8. The air tube of claim 7 , further comprising an igniter tube extending through and from the outer plate.

9. The air tube of claim 7 , wherein the plurality of struts are generally circumferentially spaced evenly around the inner cylindrical tube.

10. The air tube of claim 7 , wherein the plurality of fins are positioned within 180 degrees of a circumference of the outer cylindrical tube.

11. A combustor for a gas turbine engine, the combustor comprising:

an inner liner circumferentially extending around a center axis longitudinal to the gas turbine engine;

an outer liner disposed outward of the inner liner with respect to the center axis, the outer liner forming a combustion chamber with the inner liner; and

an air tube, including

an inner tube shaped as a hollow cylinder, a portion of the inner tube extending through the outer liner, having

an outer surface,

an inner tube inlet disposed radially outward from the outer liner with respect to the center axis, and

an inner tube outlet disposed opposite of the inner tube inlet and within the combustion chamber, the inner tube outlet in fluid communication with the inner tube inlet,

an outer tube shaped as a hollow cylinder, disposed outward of the inner tube, having

an inner surface,

an outer tube inlet disposed outward of the outer liner with respect to the center axis,

an outer tube outlet opposite the outer tube inlet and disposed with the combustion chamber, the outer tube outlet in flow communication with the outer tube inlet, and

a plurality of fins extending from the outer tube outlet towards the outer tube inlet, the plurality of fins extend towards the inner tube;

a strut coupling the outer surface of the inner tube to the inner surface of the outer tube, the strut extending from the inner tube inlet towards the inner tube outlet; and

wherein the plurality of fins are disposed downstream of the strut, in which downstream is relative to an air flow direction within the air tube, and the plurality of fins vary in length with respect to an air tube axis.

12. The combustor of claim 11 , wherein the air tube further comprises an outer plate disposed outward of and circumferentially connected to the outer tube, the outer plate connected to the outer liner.

13. The combustor of claim 12 , wherein the plurality of fins increase a surface area of the outer tube.

14. The combustor of claim 13 , wherein the air tube is made of metal and the outer plate has a surface texture created by an additive manufacturing process.

15. The combustor of claim 12 , wherein an effective area between the inner tube and outer tube is selected to enhance temperature performance of the air tube.

16. The combustor of claim 12 , wherein each of the plurality of fins has a triangular shape.