Inlet guide vane assembly for reducing airflow swirl distortion of an aircraft aft fan

1. A propulsion system for an aircraft having a fuselage, the propulsion system comprising:

an aft engine configured to be mounted to the aircraft at an aft end of the aircraft, the aft engine defining a central axis, the aft engine comprising a fan comprising a plurality of fan blades rotatable about a fan shaft and a nacelle surrounding the plurality of fan blades;

an inlet guide vane assembly comprising:

a plurality of inlet guide vanes grouped into a plurality of inlet guide vane groups, each of the inlet guide vanes comprising a shape and an orientation corresponding to airflow conditions entering the fan, the inlet guide vane groups spaced circumferentially around the central axis as a function of the airflow conditions entering the fan,

wherein the aft engine is configured as a boundary layer ingestion fan.

2. The propulsion system of claim 1 , wherein the inlet guide vane groups are evenly spaced apart about the fan shaft.

3. The propulsion system of claim 1 , wherein the inlet guide vane groups are randomly spaced apart about the fan shaft.

4. The propulsion system of claim 2 , further comprising at least four inlet guide vane groups.

5. The propulsion system of claim 4 , wherein the four inlet guide vane groups are located at a substantially twelve o'clock, a substantially three o'clock, a substantially six o'clock, and a substantially nine o'clock with respect to the central axis and the nacelle.

6. The propulsion system of claim 1 , wherein a leading edge radius of one or more of the inlet guide vanes is designed as a function of the airflow conditions entering the fan.

7. The propulsion system of claim 6 , wherein the leading edge radius of one or more of the inlet guide vanes varies in a span-wise direction as a function of the airflow conditions entering the fan.

8. The propulsion system of claim 1 , wherein the aft engine is configured to be mounted to an aircraft having a pair of wings, and wherein the propulsion system further includes two or more aircraft engines, each of which mounted to one of the pair of wings of the aircraft.

9. A boundary layer ingestion fan assembly for mounting to an aft end of a fuselage of an aircraft, the boundary layer ingestion fan assembly comprising:

a fan rotatable about a central axis of the boundary layer ingestion fan assembly, the fan comprising a plurality of fan blades rotatable about a fan shaft;

a nacelle surrounding the plurality of fan blades of the fan, the nacelle defining an inlet with the fuselage of the aircraft, the inlet extending substantially around the fuselage of the aircraft when the boundary layer ingestion fan assembly is mounted at the aft end of the aircraft; an inlet guide vane assembly mounted to the fan shaft and the nacelle, the assembly comprising:

a plurality of inlet guide vanes grouped into a plurality of inlet guide vane groups, each of the inlet guide vanes comprising a shape and an orientation corresponding to airflow conditions entering the fan, the inlet guide vane groups spaced circumferentially around the fan shaft as a function of the airflow conditions entering the fan.

10. The boundary layer ingestion fan assembly of claim 9 , wherein the inlet guide vane groups are evenly spaced apart about the fan shaft.

11. The boundary layer ingestion fan assembly of claim 9 , wherein the inlet guide vane groups are randomly spaced apart about the fan shaft.

12. The boundary layer ingestion fan assembly of claim 10 , further comprising at least four inlet guide vane groups.

13. The boundary layer ingestion fan assembly of claim 12 , wherein the four inlet guide vane groups are located at a substantially twelve o'clock, a substantially three o'clock, a substantially six o'clock, and a substantially nine o'clock with respect to the central axis and the nacelle.

14. The boundary layer ingestion fan assembly of claim 9 , wherein a leading edge radius of one or more of the inlet guide vanes is designed as a function of the airflow conditions entering the fan.

15. The boundary layer ingestion fan assembly of claim 14 , wherein the leading edge radius of one or more of the inlet guide vanes varies in a span-wise direction as a function of the airflow conditions entering the fan.

16. An aerodynamic inlet guide vane assembly for reducing airflow swirl distortion entering an aft fan mounted to a fuselage of an aircraft, the inlet guide vane assembly configured for mounting to fan shaft and a nacelle of the aft fan, the inlet guide vane assembly comprising:

a plurality of inlet guide vanes grouped into a plurality of inlet guide vane groups,

wherein each of the inlet guide vanes comprises a shape and an orientation corresponding to airflow conditions entering the fan, and

wherein the inlet guide vane groups are spaced circumferentially around the fan shaft as a function of the airflow conditions entering the fan.

17. The stabilizer assembly of claim 16 , further comprising at least four inlet guide vane groups.

18. The stabilizer assembly of claim 17 , wherein the four inlet guide vane groups are located at a substantially twelve o'clock, a substantially three o'clock, a substantially six o'clock, and a substantially nine o'clock with respect to the central axis and the nacelle.

19. The stabilizer assembly of claim 16 , wherein a leading edge radius of one or more of the inlet guide vanes varies in a span-wise direction as a function of the airflow conditions entering the fan.