Three-stream engine having a heat exchanger

1. A three-stream engine comprising:

a fan section;

a core engine disposed downstream of the fan section, the core engine comprising a booster compressor disposed upstream from a high pressure compressor;

a core cowl annularly encasing the core engine and at least partially defining a core duct, wherein the booster compressor and the high pressure compressor are encased within the core cowl;

a fan cowl disposed radially outward from the core cowl and annularly encasing at least a portion of the core cowl, the fan cowl at least partially defining an inlet duct, and the fan cowl and the core cowl at least partially defining a fan duct, the fan duct and the core duct at least partially co-extending axially on opposite sides of the core cowl;

at least one stationary strut that couples the core cowl to the fan cowl and extends radially through the fan duct, wherein the at least one stationary strut is disposed axially between the booster compressor and the high pressure compressor;

a heat exchanger disposed within the fan duct, the heat exchanger comprising a first wall and a second wall, the first wall in contact with and coupled to the at least one stationary strut, the second wall positioned on an interior surface of the fan cowl and on an exterior surface or of the core cowl, the first wall and the second wall each extending radially from the core cowl to the fan cowl into the fan duct, and the at least one stationary strut and the first wall circumferentially spaced apart from the second wall, wherein the first wall is fixed relative to the at least one stationary strut and the second wall is moveable relative to the interior surface and the exterior surface to allow for thermal expansion of the heat exchanger, and wherein the heat exchanger provides for thermal communication between a fluid flowing through the fan duct and a motive fluid flowing through the heat exchanger.

2. The three-stream engine of claim 1 , wherein between 10% and 100% of the fluid flowing through the fan duct passes through the heat exchanger.

3. The three-stream engine of claim 1 , wherein the heat exchanger is a plurality of heat exchangers circumferentially arranged within the fan duct.

4. The three-stream engine of claim 3 , wherein the plurality of heat exchangers are circumferentially spaced apart from one another.

5. The three-stream engine of claim 3 , wherein each heat exchanger in the plurality of heat exchangers includes a motive fluid inlet, a motive fluid circuit, and a motive fluid outlet.

6. The three-stream engine of claim 5 , wherein the motive fluid inlet of each heat exchanger of the plurality of heat exchangers is independently fluidly coupled to a motive fluid supply, and wherein the motive fluid outlet of each heat exchanger is independently fluidly coupled to a motive fluid return.

7. The three-stream engine of claim 5 , wherein the motive fluid outlet of a first heat exchanger in the plurality of heat exchangers is fluidly coupled to the motive fluid inlet of a second heat exchanger in the plurality of heat exchangers.

8. The three-stream engine of claim 1 , wherein the inlet duct extends from an inlet downstream from the fan section to a leading edge of the core cowl.

9. The three-stream engine of claim 8 , wherein the fan duct and the core duct each extend from a respective inlet defined partially by the leading edge of the core cowl to a respective outlet.

10. The three-stream engine of claim 9 , wherein the core engine further comprises a combustion chamber, a high pressure turbine, and a low pressure turbine arranged in a serial flow order within the core duct.

11. The three-stream engine of claim 1 , wherein the heat exchanger is coated with an ice-phobic coating.

12. A method of operating a three-stream engine,

the three-stream engine comprising:

a fan section;

a core engine disposed downstream of the fan section, the core engine comprising a booster compressor disposed upstream from a high pressure compressor;

a core cowl annularly encasing the core engine and at least partially defining a core duct, wherein the booster compressor and the high pressure compressor are encased within the core cowl;

a fan cowl disposed radially outward from the core cowl and annularly encasing at least a portion of the core cowl, the fan cowl at least partially defining an inlet duct, and the fan cowl and the core cowl at least partially defining a fan duct, the fan duct and the core duct at least partially co-extending axially on opposite sides of the core cowl;

at least one stationary strut that couples the core cowl to the fan cowl and extends radially through the fan duct, wherein the at least one stationary strut is disposed axially between the booster compressor and the high pressure compressor;

a heat exchanger disposed within the fan duct, the heat exchanger comprising a first wall and a second wall, the first wall in contact with and coupled to the at least one stationary strut, the second wall positioned on an interior surface of the fan cowl and on an exterior surface of the core cowl, the first wall and the second wall each extending radially from the core cowl to the fan cowl into the fan duct, and the at least one stationary strut and the first wall circumferentially spaced apart from the second wall, wherein the first wall is fixed relative to the at least one stationary strut and the second wall is moveable relative to the interior surface and the exterior surface to allow for thermal expansion of the heat exchanger, and wherein the heat exchanger provides for thermal communication between a fluid flowing through the fan duct and a motive fluid flowing through the heat exchanger;

the method comprising:

operating the fan section to produce a stream of air within the inlet duct, the inlet duct at least partially defined by the fan cowl;

directing a first portion of the stream of air into the core duct defined at least partially by the core cowl;

directing a second portion of the stream of air into the fan duct at least partially defined by the core cowl and the fan cowl; and

passing an amount of the second portion of the stream of air into the heat exchanger positioned within the fan duct to cool the motive fluid traveling through the heat exchanger.

13. The method of claim 12 , further comprising:

maintaining an external heat exchanger temperature that prevents formation of ice on an exterior surface of the heat exchanger.

14. The method of claim 12 , wherein the inlet duct extends from an inlet downstream from the fan section to a leading edge of the core cowl.

15. A gas turbine engine comprising:

a fan section;

a core engine disposed downstream of the fan section; a

a core cowl annularly arranged outward of the core engine and a fan cowl disposed radially outward from the core cowl and annularly encasing at least a portion of the core cowl, and the fan cowl and the core cowl at least partially defining a fan duct, the fan duct and the core duct at least partially co-extending axially on opposite sides of the core cowl;

at least one stationary strut that couples the core cowl to the fan cowl and extends radially through the fan duct, wherein the at least one stationary strut is disposed axially between a booster compressor and a high pressure compressor of the gas turbine engine; and

a heat exchanger disposed within the fan duct, the heat exchanger comprising a first wall and a second wall, the first wall in contact with and coupled to the at least one stationary strut, the second wall positioned on an interior surface of the fan cowl and on an exterior surface of the core cowl, the first wall and the second wall each extending radially from the core cowl to the fan cowl into the fan duct, and the at least one stationary strut and the first wall circumferentially spaced apart from the second wall, wherein the first wall is fixed relative to the at least one stationary strut and the second wall is moveable relative to the interior surface and the exterior surface to allow for thermal expansion of the heat exchanger, and wherein the heat exchanger provides for thermal communication between a fluid flowing through the fan duct and a motive fluid flowing through the heat exchanger.