Aircraft propulsion system with a low-fan-pressure-ratio engine in a forward over-wing-flow installation, and method of installing the same

Patent metadata

Field	Value
Publication number	US-2020002014-A1
Application number	US-201816022664-A
Country	US
Kind code	A1
Filing date	Jun 28, 2018
Priority date	Jun 28, 2018
Publication date	Jan 2, 2020
Grant date	—

Abstract

There is provided a propulsion system for an aircraft, the system having a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft. The engine has a core, a variable pitch fan, and a nacelle having a nacelle trailing edge with a top-most portion positioned above a wing leading edge. The engine has an L/D ratio of the nacelle in a range of from 0.6 to 1.0, and a fan-pressure-ratio in a range of from 1.10 to 1.30. The forward over-wing-flow installation enables, during all flight phases of the aircraft, a fan flow exhaust to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing. During a cruise flight phase of the aircraft, the engine minimizes scrubbing drag of the fan flow exhaust to the wing.

First claim

What is claimed is:

1 . A propulsion system for an aircraft, comprising:
a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft, the low-fan-pressure-ratio engine comprising:
a core having a first end and a second end;
a variable pitch fan coupled to the first end of the core;
a nacelle surrounding the variable pitch fan and a portion of the core, the nacelle having a nacelle leading edge and a nacelle trailing edge, the nacelle trailing edge having a top-most portion configured to be positioned above a wing leading edge of the wing, and the nacelle configured to be positioned, in its entirety, at a forward location in front of the wing leading edge;
a length to diameter (L/D) ratio of the nacelle in a range of from 0.6 to 1.0; and
a fan-pressure-ratio in a range of from 1.10 to 1.30,
wherein the forward over-wing-flow installation of the low-fan-pressure-ratio engine of the propulsion system enables, during all flight phases of the aircraft, a fan flow exhaust, exhausted by the variable pitch fan, to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing, and further wherein during a cruise flight phase of the aircraft, the low-fan-pressure-ratio engine minimizes scrubbing drag of the fan flow exhaust to the wing.

2 . The propulsion system of claim 1 , wherein the low-fan-pressure-ratio engine comprises a very-high-bypass-ratio engine having a bypass ratio in a range of from 15 to 50.

3 . The propulsion system of claim 1 , wherein the top-most portion of the nacelle trailing edge is configured to be positioned at a position comprising a raised position raised above the wing leading edge.

4 . The propulsion system of claim 1 , wherein the fan flow exhaust, exhausted by the variable pitch fan behind the nacelle, assists in lift of the aircraft during a takeoff flight phase of the aircraft, and during a landing flight phase of the aircraft.

5 . The propulsion system of claim 1 , wherein the fan flow exhaust, exhausted by the variable pitch fan behind the nacelle, minimally affects lift of the aircraft during the cruise flight phase of the aircraft.

6 . An aircraft comprising:
a fuselage; at least one wing operatively coupled to the fuselage, the at least one wing having a wing leading edge and a wing trailing edge; and a propulsion system operatively coupled to the at least one wing, the propulsion system comprising: a low-fan-pressure-ratio engine coupled to the at least one wing, in a forward over-wing-flow installation, the low-fan-pressure-ratio engine comprising:
a core having a first end and a second end;
a variable pitch fan coupled to the first end of the core;
a nacelle surrounding the variable pitch fan and a portion of the core, the nacelle having a nacelle leading edge and a nacelle trailing edge, the nacelle trailing edge having a top-most portion positioned above the wing leading edge, and the nacelle configured to be positioned, in its entirety, at a forward location in front of the wing leading edge;
a length to diameter (L/D) ratio of the nacelle in a range of from 0.6 to 1.0; and
a fan-pressure-ratio in a range of from 1.10 to 1.30,
wherein the forward over-wing-flow installation of the low-fan-pressure-ratio engine of the propulsion system enables, during all flight phases of the aircraft, a fan flow exhaust, exhausted by the variable pitch fan, to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the at least one wing and under the at least one wing, and further wherein during a cruise flight phase of the aircraft, the low-fan-pressure-ratio engine minimizes scrubbing drag of the fan flow exhaust to the wing.

7 . The aircraft of claim 6 , further comprising a modified high lift system operatively coupled to the at least one wing, the modified high lift system comprising one or more high lift devices operatively coupled to the wing leading edge and to the wing trailing edge, the one or more high lift devices comprising:
one or more trimmed leading edge devices, each having one or more trimmed portions, the one or more trimmed leading edge devices positioned directly behind the nacelle, and the one or more trimmed portions having a total trimmed length substantially corresponding to a length of a fan diameter of the variable pitch fan; and one or more trailing edge flaps positioned behind the one or more trimmed leading edge devices, the one or more trailing edge flaps having a limited angular motion and a simplified flap architecture.

8 . The aircraft of claim 7 , wherein the one or more trimmed leading edge devices comprise a trimmed inboard Krueger flap and a trimmed outboard slat.

9 . The aircraft of claim 7 , wherein the total trimmed length comprises at least 80% (eighty percent) of a length of the wing leading edge positioned directly behind the nacelle.

10 . The aircraft of claim 7 , wherein the one or more trailing edge flaps comprise one or more of, an inboard trailing edge flap, an outboard trailing edge flap, a simple hinge flap, a plain flap, and a single part flap.

11 . The aircraft of claim 6 , wherein the low-fan-pressure-ratio engine comprises a very-high-bypass-ratio engine having a bypass ratio in a range of from 15 to 50.

12 . The aircraft of claim 6 , wherein the top-most portion of the nacelle trailing edge is positioned at a position comprising a raised position raised above the wing leading edge.

13 . The aircraft of claim 6 , wherein the fan flow exhaust, exhausted by the variable pitch fan behind the nacelle, assists in lift of the aircraft during a takeoff flight phase of the aircraft, and during a landing flight phase of the aircraft.

14 . The aircraft of claim 6 , wherein the fan flow exhaust, exhausted by the variable pitch fan behind the nacelle, minimally affects lift of the aircraft during the cruise flight phase of the aircraft.

15 . The aircraft of claim 6 , wherein the forward over-wing-flow installation of the low-fan-pressure-ratio engine does not require changing a length, or a weight, of a landing gear assembly of the aircraft.

16 . A method of installing a low-fan-pressure-ratio engine in a forward over-wing-flow installation on an aircraft, the method comprising:
providing the aircraft comprising:
a fuselage; and
at least one wing operatively coupled to the fuselage, the at least one wing having a wing leading edge and a wing trailing edge; and
installing the low-fan-pressure-ratio engine in the forward over-wing-flow installation on the aircraft, the low-fan-pressure-ratio engine comprising:
a core having a first end and a second end;
a variable pitch fan coupled to the first end of the core;
a nacelle surrounding the variable pitch fan and a portion of the core, the nacelle having a nacelle leading edge and a nacelle trailing edge;
a length to diameter (L/D) ratio of the nacelle in a range of from 0.6 to 1.0; and
a fan-pressure-ratio in a range of from 1.10 to 1.30,
the installing the low-fan-pressure-ratio engine in the forward over-wing-flow installation comprising:
positioning the nacelle, in its entirety, at a forward location in front of the wing leading edge;
positioning a top-most portion of the nacelle trailing edge above the wing leading edge;
coupling the core to the at least one wing, via an engine mount structure; and
enabling, during all flight phases of the aircraft, a fan flow exhaust, exhausted by the variable pitch fan, to flow behind th

Assignees

• Boeing Co

Inventors

• Vassberg John C
• Dehaan Mark
• Sclafani Tony J

Classifications

• F02K1/52

  Nozzles specially constructed for positioning adjacent to another nozzle or to a fixed member, e.g. fairing · CPC title

• F02K3/068

  being characterised by a short axial length relative to the diameter · CPC title

• F02K3/06 Primary

  with front fan · CPC title

• F05D2220/323

  for aircraft propulsion, e.g. jet engines · CPC title

• B64D33/04

  of exhaust outlets or jet pipes · CPC title