Variable-Geometry Ducted Fan

• US 20170159674A1
• Filed: 12/03/2015
• Published: 06/08/2017
• Est. Priority Date: 12/03/2015
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Maciolek, Robert F.
• Granted Patent: US 10,570,926 B2
• Time in Patent Office: Days
• CPC Class Codes: B64C 11/001 Shrouded propellers
• CPC Class Codes: B64C 29/0033 the propellers being tiltable relative to the fuselage
• CPC Class Codes: B64C 7/02 Nacelles
• CPC Class Codes: B64D 33/04 of exhaust outlets or jet pipes exhaust outlets for combustion engines in general F01N; jet pipes or nozzles for jet-propulsion plants per se F02K; plants characterised by the form or arrangement of the jet pipe or nozzle F02K ; attitude, flight direction, or altitude control by jet reaction B64C
• CPC Class Codes: B64D 35/04 characterised by the transmission driving a plurality of propellers or rotors
• CPC Class Codes: F02K 1/12 by means of pivoted flaps
• CPC Class Codes: F04D 19/002 Axial flow fans
• CPC Class Codes: F04D 29/547 having a special shape in order to influence fluid flow
• CPC Class Codes: F04D 29/563 specially adapted for elastic fluid pumps
• CPC Class Codes: F05B 2240/123 Nozzles
• CPC Class Codes: F05B 2250/02 variable

Abstract

A variable-geometry ducted fan may include an air duct having a longitudinal axis, the air duct including an inlet of the variable-geometry ducted fan, a fan rotatably mounted within the air duct downstream from the inlet, the fan including fan blades defining a fan area, and a variable-area nozzle coupled to the air duct downstream from the fan, the variable-area nozzle including an exhaust of the variable-geometry ducted fan having a variable exhaust area.

Claims

1. A variable-geometry ducted fan comprising:

an air duct having a longitudinal axis, said air duct comprising an inlet of said variable-geometry ducted fan;

a fan rotatably mounted within said air duct downstream from said inlet, said fan comprising fan blades defining a fan area; and

a variable-area nozzle coupled to said air duct downstream from said fan, said variable-area nozzle comprising an exhaust of said variable-geometry ducted fan having a variable exhaust area.

2. The variable-geometry ducted fan of claim 1 wherein said variable-area nozzle expands relative to said longitudinal axis to increase said exhaust area of said exhaust for vertical flight.

3. The variable-geometry ducted fan of claim 2 wherein a ratio of said exhaust area to said fan area is approximately 1.30.

4. The variable-geometry ducted fan of claim 1 wherein said variable-area nozzle contracts relative to said longitudinal axis to decrease said exhaust area for horizontal flight.

5. The variable-geometry ducted fan of claim 4 wherein a ratio between said exhaust area and said fan area is approximately 0.98.

6. The variable-geometry ducted fan of claim 1 wherein said variable-area nozzle comprises a circumferential array of pedals pivotably coupled to said air duct and circumscribing said longitudinal axis.

7. The variable-geometry ducted fan of claim 6 wherein said pedals pivot radially outward relative to said longitudinal axis to increase said exhaust area of said exhaust for vertical flight.

8. The variable-geometry ducted fan of claim 7 wherein said pedals pivot radially outward at an angle of approximately positive ten degrees relative to said longitudinal axis to increase said exhaust area of said exhaust for said vertical flight.

9. The variable-geometry ducted fan of claim 6 wherein said pedals pivot radially inward relative to said longitudinal axis to decrease said exhaust area of said exhaust for horizontal flight.

10. The variable-geometry ducted fan of claim 9 wherein said pedals pivot radially inward at an angle of approximately negative three degrees relative to said longitudinal axis to decrease said exhaust area of said exhaust for said horizontal flight.

11. The variable-geometry ducted fan of claim 1 wherein:

said variable-geometry ducted fan comprises an overall length,

said fan comprises a fan diameter, and

a ratio of said overall length to said fan diameter is approximately 0.875.

12. The variable-geometry ducted fan of claim 11 further comprising stators mounted within said air duct downstream from said fan blades.

13. The variable-geometry ducted fan of claim 12 wherein:

said fan blades are located at a position approximately 25 percent of said overall length of said variable-geometry ducted fan downstream from said inlet, and

said stators are located a minimum distance downstream from said fan blades approximately equal to a chord dimension of said fan blades.

14. The variable-geometry ducted fan of claim 1 further comprising an actuation system operatively coupled to said variable-area nozzle to expand and contract said variable-area nozzle relative to said longitudinal axis.

15. An aircraft comprising:

a vehicle body; and

at least one variable-geometry ducted fan coupled to said vehicle body, wherein said variable-geometry ducted fan is rotatable between an approximately vertical orientation and an approximately horizontal orientation, and wherein said variable-geometry ducted fan comprises;

an air duct having a longitudinal axis, said air duct comprising an inlet of said variable-geometry ducted fan;

a fan rotatably mounted within said air duct downstream from said inlet, said fan comprising fan blades defining a fan area; and

a variable-area nozzle coupled to said air duct downstream from said fan, said variable-area nozzle comprising an exhaust of said variable-geometry ducted fan having a variable exhaust area.

16. The aircraft of claim 15 wherein:

said variable-area nozzle expands relative to said longitudinal axis to increase said exhaust area of said exhaust when said variable-geometry ducted fan is in said approximately vertical orientation for vertical flight of said aircraft, and

said variable-area nozzle contracts relative to said longitudinal axis to decrease said exhaust area when said variable-geometry ducted fan is in said approximately horizontal orientation for horizontal flight of said aircraft.

17. The aircraft of claim 16 wherein:

when said variable-area nozzle expands for said vertical flight, a ratio of said exhaust area to said fan area is approximately 1.30, and

when said variable-area nozzle contracts for said horizontal flight, said ratio between said exhaust area and said fan area is approximately 0.98.

18. The aircraft of claim 15 wherein said variable-area nozzle comprises a circumferential array of pedals pivotably coupled to said air duct and circumscribing said longitudinal axis.

19. The aircraft of claim 18 wherein:

said pedals pivot radially outward relative to said longitudinal axis to increase said exhaust area of said exhaust when said variable-geometry ducted fan is in said approximately vertical orientation for vertical flight of said aircraft, and

said pedals pivot radially inward relative to said longitudinal axis to decrease said exhaust area of said exhaust when said variable-geometry ducted fan is in said approximately horizontal orientation for horizontal flight of said aircraft.

20. A method comprising:

positioning a variable-geometry ducted fan in one of an approximately vertical orientation or an approximately horizontal orientation, said variable-geometry ducted fan comprising;

an air duct comprising an inlet of said variable-geometry ducted fan;

a fan rotatably mounted within said air duct downstream from said inlet; and

a variable-area nozzle coupled to said air duct downstream from said fan and comprising an exhaust of said variable-geometry ducted fan;

one of;

expanding said variable-area nozzle relative to a longitudinal axis of said variable-geometry ducted fan to increase an exhaust area of said exhaust when said variable-geometry ducted fan is in said approximately vertical orientation for vertical flight;

or

contracting said variable-area nozzle relative to said longitudinal axis of said variable-geometry ducted fan to decrease said exhaust area of said exhaust when said variable-geometry ducted fan is in said approximately horizontal orientation for horizontal flight;

drawing air into said variable-geometry ducted fan through said inlet;

moving said air through said variable-area nozzle; and

exiting said air from said variable-geometry ducted fan through said exhaust to generate thrust suitable to enable one of said vertical flight or said horizontal flight depending upon said orientation of said variable-geometry ducted fan.