Rotational annular airscrew with integrated acoustic arrester

Patent metadata

Field	Value
Publication number	US-9476385-B2
Application number	US-201213674377-A
Country	US
Kind code	B2
Filing date	Nov 12, 2012
Priority date	Nov 12, 2012
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

A propulsion system and methods are presented. A substantially tubular structure comprises a central axis through a longitudinal geometric center, and a first fan rotates around the central axis, and comprises a first fan hub and first fan blades. The fan hub is rotationally coupled to the substantially tubular structure, and the first fan blades are coupled to the first fan hub and increase in chord length with increasing distance from the first fan hub. A second fan is rotationally coupled to the substantially tubular structure and rotates around the central axis and contra-rotates relative to the first fan. Second fan blades are coupled to the second fan hub, and a nacelle circumscribing the first fan and the second fan is coupled to and rotates with the first fan.

First claim

The invention claimed is:

1. A propulsion system comprising:
a substantially tubular structure comprising a central axis through a longitudinal geometric center;
a first fan configured to rotate around the central axis and comprising:
a first fan hub rotationally coupled to the substantially tubular structure; and
a plurality of first fan blades coupled to the first fan hub and increasing in chord length with increasing distance from the first fan hub;

a second fan configured to rotate around the central axis and contra-rotate relative to the first fan and comprising:
a second fan hub rotationally coupled to the substantially tubular structure; and
a plurality of second fan blades coupled to the second fan hub; and

a nacelle circumscribing the first fan and the second fan, and coupled to and configured to rotate with the first fan,
wherein the nacelle comprises an annular inlet and a cylindrical outlet.

2. The propulsion system of claim 1 , further comprising:
a contra-rotating first coaxial electric motor coupled to a contra-rotating second coaxial motor and operable to be controllable individually to contra rotate relative to each other;
the first fan blades and the second fan blades coupled to the contra-rotating first coaxial electric motor and the contra-rotating second coaxial motor respectively; and
a substantially conical close-out end of the substantially tubular structure coupled to the contra-rotating first coaxial electric motor.

3. The propulsion system of claim 1 , further comprising a downward and sideward looking portion of a narrowing length of the substantially conical close-out end of the substantially tubular structure coated with an acoustic attenuating coating.

4. The propulsion system of claim 3 , wherein acoustic energy that radiates forward from the nacelle to the substantially conical close-out end is attenuated by the acoustic attenuating coating.

5. The propulsion system of claim 1 , wherein the substantially conical close-out end comprises an acoustic lining that circumscribes at least 180 degrees of a lower hemisphere of the substantially tubular structure.

6. The propulsion system of claim 5 , wherein the acoustic lining circumscribes an additional angular increment above the lower hemisphere that corresponds to a substantially maximum anticipated bank angle.

7. The propulsion system of claim 1 , wherein the substantially conical close-out end comprises acoustic lining that extends longitudinally forward to a point where a cross section of the substantially tubular structure is constant.

8. A propulsion system comprising:
a substantially tubular structure comprising a central axis through a longitudinal geometric center;
a first fan configured to rotate around the central axis and comprising:
a first fan hub rotationally coupled to the substantially tubular structure; and
a plurality of first fan blades coupled to the first fan hub and increasing in chord length with increasing distance from the first fan hub;

a second fan configured to rotate around the central axis and contra-rotate relative to the first fan and comprising:
a second fan hub rotationally coupled to the substantially tubular structure; and
a plurality of second fan blades coupled to the second fan hub;

a nacelle circumscribing the first fan and the second fan, and coupled to and configured to rotate with the first fan;
a contra-rotating first coaxial electric motor coupled to a contra-rotating second coaxial motor and operable to be controllable individually to contra rotate relative to each other;
the first fan blades and the second fan blades coupled to the contra-rotating first coaxial electric motor and the contra-rotating second coaxial motor respectively; and
a substantially conical close-out end of the substantially tubular structure coupled to the contra-rotating first coaxial electric motor.

9. The propulsion system of claim 8 , further comprising a downward and sideward looking portion of a narrowing length of the substantially conical close-out end of the substantially tubular structure coated with an acoustic attenuating coating.

10. The propulsion system of claim 9 , wherein acoustic energy that radiates forward from the nacelle to the substantially conical close-out end is attenuated by the acoustic attenuating coating.

11. The propulsion system of claim 8 , wherein the substantially conical close-out end comprises an acoustic lining that circumscribes at least 180 degrees of a lower hemisphere of the substantially tubular structure.

12. The propulsion system of claim 11 , wherein the acoustic lining circumscribes an additional angular increment above the lower hemisphere that corresponds to a substantially maximum anticipated bank angle.

13. The propulsion system of claim 8 , wherein the substantially conical close-out end comprises acoustic lining that extends longitudinally forward to a point where a cross section of the substantially tubular structure is constant.

14. The propulsion system of claim 8 ,
wherein a portion of the nacelle is extended to cover the second fan blades and configured to contra-rotate relative to the second fan.

15. The propulsion system of claim 8 , wherein the nacelle is positioned such that a center of gravity of the nacelle is located proximate to an intersection of a longitudinal axis and radial axis of the first fan blades.

16. The propulsion system of claim 8 , wherein a first fan blade chord length of the first fan blades is about twice a length of a second fan blade chord length of the second fan blades.

17. The propulsion system of claim 8 , wherein a fan-blade tip chord of the first fan blades is about 50% larger than a root chord of the first fan blades.

18. The propulsion system of claim 8 , wherein an inner mold line of the nacelle is coated with an acoustic attenuating coating.

19. The propulsion system of claim 18 , wherein an entire narrowing length of a substantially conical close-out end of the substantially tubular structure is coated with the acoustic attenuating coating.

20. The propulsion system of claim 8 , wherein the first fan blades comprise five fan blades and the second fan blades comprise three fan blades.

21. The propulsion system of claim 8 , wherein, to optimize performance and external noise at different flight speeds, the first fan is configured to switch between a fixed configuration and a rotating configuration.

22. The propulsion system of claim 8 , wherein the nacelle comprises an annular forward inlet and a cylindrical outlet aft.

23. The propulsion system of claim 22 , wherein a length of the nacelle is substantially twice the cylindrical outlet aft.

24. The propulsion system of claim 8 , wherein the second fan comprises a radial axis perpendicular to a longitudinal axis that passes through a center of the second hub of the second fan.

25. The propulsion system of claim 8 , wherein the substantially tubular structure comprises a fuselage of one of: a UAV, and a transport aircraft.

26. The propulsion system of claim 8 , wherein the first fan comprises a first fan radial axis perpendicular to a first fan longitudinal axis that passes through a center of the first fan hub.

27. The propulsion system of claim 26 , wherein a center of gravity of the nacelle is located within about 5 mm of an intersection of the first fan longitudinal axis and the first fan radial axis.

Assignees

• Boeing Co

Inventors

• Moore Matthew D
• Boren Kelly L

Classifications

• F02K1/44

  Nozzles having means, e.g. a shield, reducing sound radiation in a specified direction (F02K1/40 takes precedence) · CPC title

• F02K5/00 Primary

  Plants including an engine, other than a gas turbine, driving a compressor or a ducted fan · CPC title

• B64C11/001 Primary

  Shrouded propellers · CPC title

• F04D29/326

  comprising a rotating shroud · CPC title

• F01D1/24

  characterised by counter-rotating rotors subjected to same working fluid stream without intermediate stator blades or the like · CPC title