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US-20260125158-A1 - AIRCRAFT WITH AN UNDUCTED FAN PROPULSOR

US20260125158A1US 20260125158 A1US20260125158 A1US 20260125158A1US-20260125158-A1

Abstract

The present disclosure is generally related to aircraft having one or more unducted fan propulsors at locations within specific regions relative to an airfoil, such as a wing or horizontal stabilizer. More specifically, the specific regions are located where there is a relatively higher pressure air flow beneath the wings or above a horizontal stabilizer. That higher pressure air flow can be utilized to provide increased thrust from the unducted fan propulsor.

Inventors

  • Sara Elizabeth Carle
  • Daniel L. Tweedt
  • Syed Arif Khalid
  • Andrew Breeze-Stringfellow
  • William Bowden

Assignees

  • GENERAL ELECTRIC COMPANY

Dates

Publication Date
20260507
Application Date
20251112

Claims (20)

  1. 1 . An aircraft comprising: a fuselage; a pair of wings extending from the fuselage, two or more unducted fan propulsors, each of the unducted fan propulsors is mounted relative to one of the wings on a high pressure side thereof, the unducted fan propulsor having a centerline (CL), a plurality of blades arranged in a forward array and a plurality of blades arranged in a rearward array, wherein only one of the forward and rearward array of blades are rotating blades and the rotating blades define a maximum outer diameter (D); a point (P) located at an intersection of the CL and a line HP perpendicular to the CL that passes through an axial midpoint between a rearward trailing edge at a root of a blade of the rearward array and a forward leading edge at a root of a blade of the forward array when the forward leading edge and rearward trailing edge of the respective blades are aligned with each other; an airfoil section having an effective quarter chord point QC; and a positioning line (R) having a length (RL) and extending from the QC to the point P of the unducted fan propulsor at an angle θ measured positive in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section when viewed looking from an outboard position towards an inboard position of the wing; wherein 0.07≤RL/D≤2.0 and θ is between 187° and 342°; wherein the unducted fan propulsor comprises a substantially annular duct relative to its centerline (CL) and comprising a heat exchanger positioned within the substantially annular duct and extending substantially continuously along the circumferential direction, wherein the heat exchanger achieves an effective transmission loss (ETL) between 5 decibels and 1 decibels during an operating condition; wherein the heat exchanger comprises a heat transfer section defining an acoustic length (L i ), and wherein an Operational Acoustic Reduction Ratio (OARR) is greater than or equal to 0.75 to achieve the ETL at the operating condition, the OARR equal to: ( sin ⁢ ( 2 × π × f a × L i ) ) 2 , wherein a is greater than or equal to 11,600 inches per second and less than or equal to 30,924 inches per second during the operating condition.
  2. 2 . The aircraft of claim 1 , wherein the substantially annular duct defines a flowpath and a duct height along a radial direction of the unducted fan propulsor, the heat exchanger defining a heat exchanger height equal to at least 10% of the duct height.
  3. 3 . The aircraft of claim 1 , wherein the unducted fan propulsor comprises a turbomachine and a rotor assembly driven by or incorporated into the turbomachine and operable at a blade passing frequency (f) greater than or equal to 300 hertz and less than or equal to 12,500 hertz during the operating condition.
  4. 4 . The aircraft of claim 3 , wherein the operating condition is a high power operating condition, wherein the blade passing frequency (f) is a first blade passing frequency (f 1 ) greater than or equal to 600 hertz and less than or equal to 12,500 hertz during the high power operating condition, and wherein a is a first speed of sound a 1 greater than or equal to 13,200 inches per second and less than or equal to 25,360 inches per second during the high power operating condition, and wherein OARR is equal to: ( sin ⁢ ( 2 × π × f 1 a 1 × L i ) ) 2 .
  5. 5 . The aircraft of claim 4 , wherein the heat exchanger is positioned in a cold location of the unducted fan propulsor, and wherein a 1 is a 1,Cold and is equal to 24,528 inches per second.
  6. 6 . The aircraft of claim 3 , wherein the heat transfer section defines a HX flow area (A HX ), wherein the substantially annular defines a duct flow area (A d ) upstream of the heat exchanger, and wherein a ratio of the HX flow area (A HX ) to the duct flow area (A d ) is greater than 1.
  7. 7 . The aircraft of claim 1 , wherein the substantially annular duct comprises spaced-apart peripheral walls extending between an inlet and an outlet and defining a flowpath, wherein the flowpath includes a diverging portion downstream of the inlet, in which a flow area is greater than a flow area at the inlet, and wherein the heat exchanger comprises: a plurality of spaced-apart fins disposed in the flowpath, each of the fins having opposed side walls extending between an upstream leading edge and a downstream trailing edge, wherein the fins divide at least the diverging portion of the flowpath into a plurality of side-by-side flow passages; and a heat transfer structure disposed within at least one of the fins.
  8. 8 . The aircraft of claim 1 , wherein 0.15≤RL/D.
  9. 9 . The aircraft of claim 1 , wherein 0.35≤RL/D.
  10. 10 . The aircraft of claim 1 , wherein RL/D is about 0.72.
  11. 11 . The aircraft of claim 1 , wherein θ is between 198° and 310°, and preferably between 205° and 285°.
  12. 12 . The aircraft of claim 1 , wherein the two or more unducted fan propulsors are configured to operate at a cruise flight Mach M 0 of between 0.7 and 0.9, and more preferably between 0.75 and 0.9; or the two or more unducted fan propulsors are configured to propel the aircraft at a cruise flight Mach M 0 of between 0.7 and 0.9, and more preferably between 0.75 and 0.85.
  13. 13 . The aircraft of claim 1 , wherein the unducted fan propulsor has a dimensionless cruise fan net thrust parameter expressed as follows: 0 . 1 ⁢ 5 > F n ⁢ e ⁢ t ρ 0 ⁢ A a ⁢ n ⁢ V 0 2 > 0 . 0 ⁢ 6 , wherein F net is cruise fan net thrust, ρ 0 is ambient air density, V o is cruise flight velocity, and A an is annular cross-sectional area perpendicular to an axis of rotation of a rotor axis of rotation.
  14. 14 . The aircraft of claim 1 , wherein the unducted fan propulsor is undermounted to the airfoil with one or more intermediate structures.
  15. 15 . The aircraft of claim 1 , wherein the P of the unducted fan propulsor is variable to accommodate different operating conditions.
  16. 16 . An aircraft, comprising: a fuselage; an airfoil extending from the fuselage, the airfoil having an airfoil section defining an effective quarter chord point (QC); an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL), a plurality of blades arranged in a forward array and a plurality of blades arranged in a rearward array, wherein only one of the forward and rearward array of blades are rotating blades and the rotating blades define a maximum outer diameter (D); a point (P) located at an intersection of the CL and a line HP perpendicular to the CL that passes through an axial midpoint between a rearward trailing edge at a root of a blade of the rearward array and a forward leading edge at a root of a blade of the forward array when the forward leading edge and rearward trailing edge of the respective blades are aligned with each other; an ellipse origin positioning line (EOR) having a length (EORL) extending from the QC to an ellipse origin (OR) at an angle θ measured positive in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and measured positive in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, when viewed looking for an outboard position towards an inboard position; wherein the P of the unducted fan propulsor is located within a first ellipse having a first major axis length (1MajAL) and a first minor axis length (1MinAL) with a first ellipse origin defined by EORL/D of 0.938 and θ of 253.6°, and where 1MajAL/D is 2.8 and 1MinAL/D is 1.7; and wherein the unducted fan propulsor comprises a substantially annular duct relative to its centerline (CL) and comprising a heat exchanger positioned within the substantially annular duct and extending substantially continuously along the circumferential direction, wherein the heat exchanger achieves an effective transmission loss (ETL) between 5 decibels and 1 decibels during an operating condition; wherein the heat exchanger comprises a heat transfer section defining an acoustic length (L i ), and wherein an Operational Acoustic Reduction Ratio (OARR) is greater than or equal to 0.75 to achieve the ETL at the operating condition, the OARR equal to: ( sin ⁢ ( 2 × π × f a × L i ) ) 2 , wherein a is greater than or equal to 11,600 inches per second and less than or equal to 30,924 inches per second during the operating condition.
  17. 17 . The aircraft of claim 16 , wherein the P of the unducted fan propulsor is located in a second ellipse having a second major axis length (2MajAL) and a second minor axis length (2MinAL) with a second ellipse origin defined by EORL/D of 1.051 and θ of 248.8°, and where 2MajAL/D is 1.86 and 2MinAL/D is 1.56.
  18. 18 . The aircraft of claim 16 , wherein the P of the unducted fan propulsor is located in a third ellipse having a third major axis length (3MajAL) and a third minor axis length (3MinAL) with a third ellipse origin defined by EORL/D of 0.870 and θ of 239.6°, where 3MajAL/D is 1.4 and 3MinAL/D is 0.9.
  19. 19 . The aircraft of claim 16 , wherein the P of the unducted fan propulsor is located in a fourth ellipse having a fourth major axis length (4MajAL) and a fourth minor axis length (4MinAL) with a fourth ellipse origin defined by EORL/D of 0.763 and θ of 235.7°, and where 4MajAL/D is 0.94 and 4MinAL/D is 0.44.
  20. 20 . An aircraft, comprising: a fuselage; an airfoil extending from the fuselage, the airfoil having an airfoil section defining an effective quarter-chord point (QC); an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL), a plurality of blades arranged in a forward array and a plurality of blades arranged in a rearward array, wherein one of the forward and rearward array of blades are rotating blades and the rotating blades define a maximum outer diameter (D); a point (P) located at an intersection of the CL and a line HP perpendicular to the CL that passes through an axial midpoint between a rearward trailing edge at a root of a blade of the rearward array and a forward leading edge at a root of a blade of the forward array when the forward leading edge and rearward trailing edge of the respective blades are aligned with each other; a positioning line (R) having a length (RL) and extending from the QC to the point P of the unducted fan propulsor at an angle θ measured positive in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and measured positive in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, when viewed looking from an outboard position towards an inboard position (e.g. the fuselage) OR when viewed with the LE to the left of the TE; wherein 0.065<RL/D<1.98 and θ is between 187° and 340°; and wherein RL/D and θ of the P of the unducted fan propulsor adhere to the following expressions: R ⁢ L D + ( 1.4161 * [ 1.88978 * sin 2 ⁢ ( θ ) - 0.0875 * cos 2 ⁢ ( θ ) + 0.477 * sin ⁢ ( θ ) * cos ⁢ ( θ ) ] + 1.764 * sin ⁢ ( θ ) + 0 . 1 ⁢ 9 ⁢ 1 ⁢ 4 ⁢ 6 * cos ⁢ ( θ ) ) 1.96 * sin 2 ⁢ ( θ ) + 0 . 7 ⁢ 2 ⁢ 2 ⁢ 5 * cos 2 ⁢ ( θ ) > 0 , and R ⁢ L D + ( - 1.4161 * [ 1.88978 * sin 2 ( θ ) - 0.0875 * cos 2 ( θ ) + 0.477 * sin ⁡ ( θ ) * cos ⁡ ( θ ) ] + 1.764 * sin ⁡ ( θ ) + 0 . 1 ⁢ 9 ⁢ 1 ⁢ 4 ⁢ 6 * cos ⁡ ( θ ) ) 1.96 * sin 2 ( θ ) + 0 . 7 ⁢ 2 ⁢ 2 ⁢ 5 * cos 2 ( θ ) < 0 ; and wherein the unducted fan propulsor comprises a substantially annular duct relative to its centerline (CL) and comprising a heat exchanger positioned within the substantially annular duct and extending substantially continuously along the circumferential direction, wherein the heat exchanger achieves an effective transmission loss (ETL) between 5 decibels and 1 decibels during an operating condition; wherein the heat exchanger comprises a heat transfer section defining an acoustic length (L i ), and wherein an Operational Acoustic Reduction Ratio (OARR) is greater than or equal to 0.75 to achieve the ETL at the operating condition, the OARR equal to: ( sin ⁢ ( 2 × π × f a × L i ) ) 2 , wherein a is greater than or equal to 11,600 inches per second and less than or equal to 30,924 inches per second during the operating condition.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of International Appl. No. PCT/US2024/040754, filed Aug. 2, 2024, which claims priority to U.S. patent application Ser. No. 18/230,609, filed on Aug. 4, 2023, and Ser. No. 18/652,052, filed May 1, 2024, the latter of which is a continuation-in-part of the former, the disclosures of which are hereby incorporated by reference in their entireties. FIELD The present disclosure relates generally to an aircraft with a fan propulsor. BACKGROUND Winged aircraft have undermounted propulsors in the form of a turboprop engine. The addition of a propulsor to a wing can lead to installation penalties, including increased drag. As the size of the undermounted propulsor increases, installation penalties can also increase, such as increased weight. BRIEF DESCRIPTION OF THE DRAWINGS A full and enabling disclosure of the aspects of the present description, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which refers to the appended figures, in which: FIG. 1 comprises a top plan view of an aircraft as configured in accordance with various embodiments of these teachings, with undermounted, unducted fan propulsors mounted on forward wings of the aircraft; FIG. 2 comprises a top plan view of an aircraft as configured in accordance with various embodiments of these teachings, with unducted fan propulsors mounted on top of horizontal stabilizers of the aircraft; FIG. 3 comprises an elevational cross-sectional view of an exemplary unducted fan propulsor having a plurality of blades arranged in a forward array and a rearward array; FIG. 4 comprises a schematic side elevation view showing the location of the unducted fan propulsor of FIG. 3 relative to an airfoil section; FIG. 5A is a schematic side elevation view similar to FIG. 4 and showing the unducted fan propulsor pitched downward relative to the airfoil section; FIG. 5B defines a pitch angle (D for the unducted fan propulsor relative to a chord line of the airfoil section in FIG. 4; FIG. 6A comprises a top plan view of the propulsor of FIG. 4 and inboard and outboard locations of the wing relative to an unducted fan propulsor centerline, with the inboard and outboard locations in FIG. 6A used to determine a chord length (C) of the airfoil section in FIG. 4; FIG. 6B comprises a schematic side elevation view of a first section and a second section of the aircraft wing, which sections are used to determine an effective quarter chord point (QC) of the airfoil section in FIG. 4; FIG. 6C comprises a schematic top plan view of a portion of an aircraft having a pair of wings extending from the fuselage with the propulsor of FIG. 3 mounted relative to each of the wings; FIG. 6D comprises a schematic front elevation view of the aircraft portion of FIG. 6C; FIG. 6E comprises a schematic top plan view of a portion of an aircraft having a pair of wings extending from the fuselage with the propulsor of FIG. 3 mounted relative to each of the wings, similar to FIG. 6C but showing the propulsors toed inwardly toward the fuselage; FIG. 7 comprises a schematic side elevation view similar to that of FIG. 4, but showing a first ellipse, a second ellipse, a third ellipse, and a fourth ellipse to illustrate various embodiments of mounting locations of one of the unducted fan propulsors relative to one of the wings; FIG. 8 comprises a schematic side elevation view similar to that of FIG. 7, but showing a first ellipse, a second ellipse, a third ellipse, and a fourth ellipse to illustrate various embodiments of mounting locations of one of the unducted fan propulsors relative to one of the horizontal stabilizers; FIG. 9 comprises a schematic side elevation view similar to that of FIG. 7, showing the first ellipse, the second ellipse, the third ellipse, and the fourth ellipse to illustrate various embodiments of mounting locations of one of the unducted fan propulsors relative to one of the wings; FIG. 10 comprises a schematic side elevation view similar to that of FIG. 8, showing the first ellipse, the second ellipse, the third ellipse, and the fourth ellipse to illustrate various embodiments of mounting locations of one of the unducted fan propulsors relative to one of the horizontal stabilizers; FIG. 11 comprises a schematic representation showing exemplary locations of a point P of one of the unducted fan propulsors, as defined herein, within the first ellipse, the second ellipse, the third ellipse, and the fourth ellipse; FIG. 12 is a schematic cross-sectional view of a three-stream engine in accordance with an exemplary embodiment of the present disclosure; FIG. 13 is a schematic cross-sectional view of a heat exchanger and flowpath in accordance with an exemplary embodiment of the present disclosure; FIG. 14 is a schematic cross-sectional view of a heat exchanger and flowpath in accordance with another exemplary embodiment of the present disclosure;