ULTRA-EFFICIENT PROPULSOR WITH AN AUGMENTOR FAN CIRCUMSCRIBING A TURBOFAN

• US 20110056183A1
• Filed: 09/09/2009
• Published: 03/10/2011
• Est. Priority Date: 09/09/2009
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Prichard, Alan K., Moore, Matthew, Seidel, Gerhad E., Sankrithi, Mithra M.K.V.
• Granted Patent: US 8,689,538 B2
• Time in Patent Office: Days
• US Class Current: 60/204
• CPC Class Codes: B64C 11/48 Units of two or more coaxial propellers
• CPC Class Codes: B64D 2027/005 Aircraft with an unducted turbofan comprising contra-rotating rotors, e.g. contra-rotating open rotors [CROR]
• CPC Class Codes: B64D 2027/026 comprising different types of power plants, e.g. combination of an electric motor and a gas-turbines
• CPC Class Codes: B64D 27/026 comprising different types of power plants, e.g. combination of a piston engine and a gas-turbine Hybrid electric aircraft B64D27/33
• CPC Class Codes: B64D 27/12 within, or attached to, wings
• CPC Class Codes: B64D 27/14 within, or attached to, fuselages
• CPC Class Codes: F01D 7/00 Rotors with blades adjustable in operation; Control thereof for reversing F01D1/30
• CPC Class Codes: F02K 3/06 with front fan
• CPC Class Codes: F02K 3/077 the plant being of the multiple flow type, i.e. having three or more flows
• CPC Class Codes: F05D 2220/324 to drive unshrouded, low solidity propeller
• CPC Class Codes: F05D 2220/325 to drive unshrouded, high solidity propeller
• CPC Class Codes: F05D 2260/96 Preventing, counteracting or reducing vibration or noise
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

An ultra-efficient “green” aircraft propulsor utilizing an augmentor fan is disclosed. A balanced design is provided combining a fuel efficient and low-noise high bypass ratio augmentor fan and a low-noise shrouded high bypass ratio turbofan. Three mass flow streams are utilized to reduce propulsor specific fuel consumption and increase performance relative to conventional turbofans. Methods are provided for optimization of fuel efficiency, power, and noise by varying mass flow ratios of the three mass flow streams. Methods are also provided for integration of external propellers into turbofan machinery.

Claims

1. An ultra-efficient aircraft propulsor comprising:

a turbofan propulsor comprising a core engine and a ducted fan driven by the core engine, the ducted fan comprising a plurality of ducted fan blades circumferentially contained by a fan cowl;

an augmentor hub ring substantially surrounding an inner perimeter of the fan cowl;

an augmentor fan driven by the core engine comprising a plurality of augmentor fan blades arranged circumferentially around the augmentor hub ring.

2. The ultra-efficient aircraft propulsor according to claim 1, further comprising drive means operable to rotationally drive the augmentor fan by using power from the core engine.

3. The ultra-efficient aircraft propulsor according to claim 1, wherein the core engine is a combustion engine that has a thermodynamic cycle comprising at least one of the group consisting of:

Brayton, Otto, Diesel, Rankine, Stirling, Humphrey, Fickett-Jacobs, Wave, Carnot, and a Hybrid.

4. The ultra-efficient aircraft propulsor according to claim 1, further comprising thrust reverser means operable to produce reverse thrust.

5. The ultra-efficient aircraft propulsor according to claim 4, wherein the thrust reverser means comprises means for changing at least one of the group consisting of:

a pitch orientation of the augmentor fan blades, fan flow, and core flow.

6. The ultra-efficient aircraft propulsor according to claim 4, wherein the thrust reverser means comprises reverser elements comprising at least one of the group consisting of:

cascade, flow deflecting vane, blocker door, clamshell, target, and petal.

7. The ultra-efficient aircraft propulsor according to claim 1, wherein the augmentor fan blades comprise airfoil sections, and wherein a number of the augmentor fan blades ranges from three to sixty inclusive.

8. The ultra-efficient aircraft propulsor according to claim 1, wherein the augmentor fan blades comprise blade pitch control means operable to variably control pitch angles of the augmentor fan blades to provide desirable augmentor fan blades angles of attack along their span to enable optimization of an optimization parameter.

9. The ultra-efficient aircraft propulsor according to claim 8, wherein the optimization parameter is a function of a measure of at least one of the group consisting of:

aerodynamic efficiency, fuel efficiency, community noise, cabin noise, emissions, takeoff performance, climb performance, cruise performance, performance in descending flight, reverse thrust performance, and power division between the augmentor fan, the ducted fan and the core engine.

10. The ultra-efficient aircraft propulsor according to claim 1, wherein the augmentor fan blades each have a span ratio ranging from about 0.05 to about 5 to a span of each of the ducted fan blades.

11. The ultra-efficient aircraft propulsor according to claim 1, wherein the augmentor fan blades each have an average chord to span ratio ranging from about 0.02 to about 2.

12. The ultra-efficient aircraft propulsor according to claim 1, wherein an activity factor of the augmentor fan blades is greater than 250.

13. The ultra-efficient aircraft propulsor according to claim 1, wherein a number of augmentor fan blades and a number of the ducted fan blades are chosen to avoid sum and difference tones.

14. The ultra-efficient aircraft propulsor according to claim 13, further comprising:

a second augmentor hub ring substantially surrounding an inner perimeter of the fan cowl and longitudinally spaced from the augmentor hub ring, and operable to contra-rotate relative to the augmentor hub ring; and

a second augmentor fan driven by the core engine comprising a plurality of second augmentor fan blades arranged circumferentially around the second augmentor hub ring, wherein a number of the second augmentor fan blades is chosen to avoid sum and difference tones.

15. The ultra-efficient aircraft propulsor according to claim 1, wherein an aerodynamic tip-sweep of a mid chord line of each of the augmentor fan blades relative to a plane perpendicular to local inflow streamlines is greater than about 10 degrees and less than or equal to about 60 degrees.

16. The ultra-efficient aircraft propulsor according to claim 1, further comprising at least a dual load path attachment operable to couple the augmentor fan blades to the augmentor hub ring.

17. The ultra-efficient aircraft propulsor according to claim 1, wherein a property of tips of the augmentor fan blades comprises at least one of the group consisting of:

nonzero taper, nonzero sweep, morphably controllable surfaces, and aerodynamic blowing.

18. The ultra-efficient aircraft propulsor according to claim 1, wherein a tip of each of the augmentor fan blades is coupled to an augmentor fan tip ring encircling all of the augmentor fan blades, and wherein the augmentor fan tip ring is operable to rotate with the augmentor fan.

19. The ultra-efficient aircraft propulsor according to claim 18, further comprising blade pitch variability operable to allow coupling of the augmentor fan blades to the augmentor fan tip ring.

20. The ultra-efficient aircraft propulsor according to claim 18, wherein the augmentor fan tip ring comprises a ring airfoil configuration.

21. The ultra-efficient aircraft propulsor according to claim 20, wherein an average chord of a ring airfoil of the ring airfoil configuration ranges from 1 to 5 times an average chord of each of the augmentor fan blades.

22. The ultra-efficient aircraft propulsor according to claim 20, wherein an average chord of the augmentor fan tip ring ranges from about 0.025 to about 0.5 of an average chord of the fan cowl.

23. The ultra-efficient aircraft propulsor according to claim 20, wherein an average thickness to chord ratio of a ring airfoil of the ring airfoil configuration ranges from about 0.03 to about 0.30.

24. The ultra-efficient aircraft propulsor according to claim 18, wherein:

the augmentor fan tip ring has a slightly noncircular shape when the augmentor fan is not rotating; and

rotational loads cause the augmentor fan tip ring to take a substantially circular shape when the augmentor fan is rotating at operational rotation speeds.

25. The ultra-efficient aircraft propulsor according to claim 1, wherein the augmentor fan blades comprise airfoil acoustic shaping features.

26. The ultra-efficient aircraft propulsor according to claim 25, wherein an aerodynamic tip-sweep of a mid chord line of each of the augmentor fan blades in degrees relative to streamlines is less than or equal to about 60.

27. The ultra-efficient aircraft propulsor according to claim 1, wherein a preferred activity factor of the augmentor fan blades is at least about 150 and at most about 250.

28. The ultra-efficient aircraft propulsor according to claim 2, wherein the drive means comprises gear means operable to transmit power concurrent with changing revolutions per minute.

29. The ultra-efficient aircraft propulsor according to claim 28, wherein the gear means comprises:

at least one driving gear ring;

at least one driven gear ring provided around a periphery of the augmentor hub ring; and

a plurality of connecting gear elements provided between the at least one driving gear ring and the at least one driven gear ring.

30. The ultra-efficient aircraft propulsor according to claim 29, wherein:

the at least one driving gear ring is provided around the inner perimeter of the fan cowl; and

the connecting gear elements comprise;

a first gear sprocket engaged by the at least one driving gear ring;

a second gear sprocket engaging the at least one driven gear ring; and

a shaft operable to connect the first gear sprocket and the second gear sprocket.

31. The ultra-efficient aircraft propulsor according to claim 28, wherein a circumference of the second gear sprocket is less than a circumference of the first gear sprocket, to cause an effective gearing wherein rotational RPM of the driven gear ring is reduced relative to rotational RPM of the driving gear ring.

32. The ultra-efficient aircraft propulsor according to claim 1, further comprising propulsor control means operable to control at least two of the group consisting of:

core engine power, core engine thrust, core engine RPM, core engine fuel flow, a core engine critical temperature parameter, ducted fan thrust, ducted fan RPM, augmentor fan blade pitch, augmentor fan thrust, and augmentor fan RPM.

33. The ultra-efficient aircraft propulsor according to claim 32, wherein the propulsor control means further comprises mass flow control means operable to control at least a fraction of propulsor total mass flow which is run through the augmentor fan.

34. The ultra-efficient aircraft propulsor according to claim 32, wherein the propulsor control means further comprises power sharing control means operable to control at least a fraction of propulsor total power which is run through the augmentor fan.

35. The ultra-efficient aircraft propulsor according to claim 1, further comprising flow vectoring means operable to vector a flow downstream of at least one of the group consisting of:

the core engine, the ducted fan, and the augmentor fan.

36. The ultra-efficient aircraft propulsor according to claim 1, wherein a diameter of the augmentor hub ring is within about ±

25% of a diameter of the ducted fan.

37. The ultra-efficient aircraft propulsor according to claim 1, wherein the core engine comprises a spool core architecture.

38. The ultra-efficient aircraft propulsor according to claim 37, wherein the spool core architecture comprises at least one of the group consisting of:

a 1-spool core architecture, a 2-spool core architecture, a 3-spool core architecture, and a 4 spool core architecture.

39. The ultra-efficient aircraft propulsor according to claim 1, wherein tips of the augmentor fan blades are substantially located on a circle of larger size and surrounding an outer perimeter of all of the ducted fan blades of the ducted fan and an outer perimeter of the fan cowl.

40. The ultra-efficient aircraft propulsor according to claim 39, further comprising bearing means operable to enable a rotating structural connection, wherein the augmentor hub ring is structurally coupled by the bearing means to the fan cowl.

41. The ultra-efficient aircraft propulsor according to claim 39, wherein a diameter of the augmentor hub ring ranges from about 15% to about 90% of a diameter of the circle.

42. The ultra-efficient aircraft propulsor according to claim 39, further comprising drive means comprising gear means operable to rotationally drive the augmentor fan at lower revolutions per minute than the ducted fan, using power from the core engine.

43. The ultra-efficient aircraft propulsor according to claim 42, wherein the gear means is further operable to drive the ducted fan at lower revolutions per minute than turbine elements of the core engine.

44. The ultra-efficient aircraft propulsor according to claim 1, further comprising a rotating gear ring operable to provide torque from blade pitch control unit drives to the augmentor fan blades.

45. The ultra-efficient aircraft propulsor according to claim 1, further comprising a lobed mixer operable to cool gasses that drive a power turbine which directly drives the augmentor fan.

46. The ultra-efficient aircraft propulsor according to claim 45, wherein cooled gasses from the lobed mixer reduces temperature related wear on the at least one of the augmentor fan blades and at least one blade pitch control drive.

47. The ultra-efficient aircraft propulsor according to claim 1, wherein the core engine comprises at least one compressor comprising at least one of the group consisting of:

an axial compressor and a centrifugal compressor.

48. The ultra-efficient aircraft propulsor according to claim 1, wherein the core engine comprises an electric motor.

49. The ultra-efficient aircraft propulsor according to claim 1, wherein the augmentor fan blades are twisted from their root ends to their tip ends.

50. A method for operating an ultra-efficient aircraft propulsor, the method comprising:

providing thrust from a core engine at a first thrust to total power ratio;

providing thrust from a ducted fan at a second thrust to total power ratio; and

providing thrust from an augmentor fan at a third thrust to total power ratio.

51. The method according to claim 50, wherein:

the third thrust to total power ratio is greater than the second thrust to total power ratio for a first set of flight conditions; and

the second thrust to total power ratio is greater than the third thrust to total power ratio for a second set of flight conditions.

52. The method according to claim 51, wherein:

the first set of flight conditions comprises takeoff; and

the second set of flight conditions comprises climb out.

53. The method according to claim 50, further comprising means for setting the first thrust to total power ratio, the second thrust to total power ratio, and the third thrust to total power for optimizing takeoff field length.

54. The method according to claim 50, further comprising providing an augmentor fan blade hub-to-tip ratio larger than a corresponding ratio for at least one of a propfan propulsor and a turboprop propulsor.

55. The method according to claim 54, wherein the augmentor fan blade hub-to-tip ratio is at least about 0.4.

56. The method according to claim 54, wherein the augmentor fan blade hub-to-tip ratio enables an increased number of augmentor fan blades.

57. The method according to claim 56, wherein the increased number of the augmentor fan blades minimizes noise by reducing a loading of the augmentor fan blades.

58. A method for generating thrust for variable cycle engine with an augmentor fan, the method comprising:

providing a first mass flow stream from an augmentor fan at a first velocity;

providing a second mass flow stream from a ducted turbofan at a second velocity, the second mass flow stream substantially circumscribed by the first mass flow stream; and

providing a third mass flow stream from a core engine at a third velocity, the third mass flow stream substantially circumscribed by the second mass flow stream.

59. The method according to claim 58, wherein the first velocity is less than the second velocity and the second velocity is less than the third velocity.

60. The method according to claim 58, wherein a first difference between the first velocity and the second velocity reduces at least one of turbulence and noise generation between the first mass flow stream and second mass flow stream.

61. The method according to claim 58, wherein a second difference between the second velocity and the third velocity reduces at least one of turbulence and noise generation between the second mass flow stream and third mass flow stream.