Supersonic aircraft and method of reducing sonic booms and jet noise

Patent metadata

Field	Value
Publication number	US-12110841-B2
Application number	US-202217652054-A
Country	US
Kind code	B2
Filing date	Feb 22, 2022
Priority date	Feb 24, 2021
Publication date	Oct 8, 2024
Grant date	Oct 8, 2024

Abstract

Provided is a supersonic aircraft including: a shield that shields an engine exhaust flow discharged from a jet engine accommodated in an engine nacelle mounted on a fuselage of the aircraft to thereby reduce sonic booms due to the engine exhaust flow; and an exhaust nozzle that is provided in an exhaust port of the engine nacelle and that generates a sound source for high-frequency components at a position at which the shield is capable of shielding the high-frequency components of the engine exhaust flow, to thereby reduce jet noise having the high-frequency components, and promotes mixing of the engine exhaust flow that generates low-frequency noise components with an external air flow to thereby reduce jet noise having the low-frequency components.

First claim

What is claimed is:

1. A supersonic aircraft, comprising:
a shield that shields an engine exhaust flow discharged from a jet engine accommodated in an engine nacelle mounted on a fuselage of the aircraft to thereby reduce sonic booms due to the engine exhaust flow; and
an exhaust nozzle that is provided in an exhaust port of the engine nacelle and that is configured to generate a sound source for high-frequency components of jet noise at a position at which the shield is capable of shielding the high-frequency components of jet noise due to the engine exhaust flow, to thereby reduce the high-frequency components of jet noise, and is configured to promote mixing of low-frequency components of jet noise due to the engine exhaust flow with an external air flow to thereby reduce the low-frequency components of jet noise,
wherein the exhaust nozzle extends to the rear of the jet engine and constitutes an exhaust flow path,
wherein the exhaust nozzle has a plurality of main nozzle pieces and at least one coupling nozzle piece,
wherein a rear end portion of each of the main nozzle pieces is provided swingably in an inward and outward direction of the exhaust flow path about an open/close bend section, the open/close bend section being formed at a rear end of a throttle section at the rear of the jet engine,
wherein the coupling nozzle piece is disposed between adjacent main nozzle pieces and is coupled bendably to the main nozzle pieces on either side thereof, the coupling nozzle piece being coupled bendably to the main nozzle pieces at a side bend section, and the coupling nozzle piece having a central bend section that is capable of forming a plurality of projecting sections inside the exhaust flow path in conjunction with a movement of each of the main nozzle pieces,
wherein, when the main nozzle pieces are swung outward from the exhaust flow path, the coupling nozzle piece forms a flat surface having no projecting section inside the exhaust flow path, and the cross-sectional area of the exhaust flow path is wider toward the rear end portion of the main nozzle pieces from the position of the open/close bend section, and
wherein, when the main nozzle pieces are swung inside the exhaust flow path, the coupling nozzle piece forms a projecting section inside the exhaust flow path along the exhaust flow path for narrowing the exhaust flow path.

2. The supersonic aircraft according to claim 1 , wherein the exhaust nozzle promotes mixing of the high-frequency components of jet noise due to the engine exhaust flow with the external air flow in vicinity of the exhaust port, to thereby generate the sound source for the high-frequency components of jet noise at the position at which the shield is capable of shielding the high-frequency components of jet noise.

3. The supersonic aircraft according to claim 1 , wherein the exhaust nozzle has a plurality of projecting sections provided in an inner circumference.

4. The supersonic aircraft according to claim 3 , wherein the plurality of projecting sections has an identical shape and an identical size and is provided at equal intervals in a circumferential direction of the exhaust nozzle.

5. The supersonic aircraft according to claim 3 , wherein the number N of the plurality of projecting sections is N>4.

6. The supersonic aircraft according to claim 3 , wherein the plurality of projecting sections each has two sides projecting in an inner circumferential direction of the exhaust nozzle as the exhaust nozzle is viewed axially, and the lengths of the two sides are equal, and
wherein, provided that the number of the plurality of projecting sections is denoted by N and a length of one side of a regular polygon having an N-number of sides is 1, a length Rf of one side of the projecting section is Rf>0.5.

7. The supersonic aircraft according to claim 6 , wherein the exhaust nozzle is one of a plurality of exhaust nozzles designed such that irrespective of the number N of the plurality of projecting sections and the length Rf of the one side of the projecting section, a cross-sectional area of each exhaust port of the plurality of exhaust nozzles is substantially equal to that of each other exhaust port of the plurality of exhaust nozzles.

8. The supersonic aircraft according to claim 3 , wherein a sound pressure level of high-frequency components of jet noise due to the exhaust nozzle with the plurality of projecting sections is higher than a sound pressure level of high-frequency components of jet noise due to the exhaust nozzle without the plurality of projecting sections, and
wherein a sound pressure level of low-frequency components of jet noise due to the exhaust nozzle with the plurality of projecting sections is lower than a sound pressure level of low-frequency components of jet noise due to the exhaust nozzle without the plurality of projecting sections.

9. The supersonic aircraft according to claim 1 , wherein the shield suppresses wrapping of the pressure waves generated by the engine exhaust flow downward around the aircraft to thereby reduce sonic booms due to the engine exhaust flow.

10. The supersonic aircraft according to claim 1 , wherein the shield includes a pair of shields disposed on the aircraft so as to sandwich the engine exhaust flow.

11. The supersonic aircraft according to claim 10 , further comprising:
a horizontal tail disposed behind the engine nacelle,
wherein the pair of shields is disposed on the horizontal tail.

12. The supersonic aircraft according to claim 11 , wherein the shield further includes the horizontal tail.

13. The supersonic aircraft according to claim 10 , wherein each of the pair of shields is inclined outward from the aircraft.

14. The supersonic aircraft according to claim 10 , further comprising an aft fuselage lifting surface provided behind the engine nacelle,
wherein the pair of shields is disposed on the aft fuselage lifting surface and has a function as a V tail.

15. The supersonic aircraft according to claim 1 , wherein the plurality of main nozzle pieces and coupling nozzle pieces constitute the whole circumference of the exhaust flow path to the rear of the jet engine.

16. The supersonic aircraft according to claim 1 , wherein during a supersonic cruise of the supersonic aircraft, the main nozzle pieces are swung outward from the exhaust flow path, and
wherein during take-off and landing of the supersonic aircraft, the main nozzle pieces are swung inside the exhaust flow path.

17. A method of reducing sonic booms and jet noise, comprising:
shielding, by a shield, an engine exhaust flow discharged from a jet engine accommodated in an engine nacelle mounted on a fuselage of an supersonic aircraft to thereby reduce sonic booms due to the engine exhaust flow;
generating, by an exhaust nozzle that is provided in an exhaust port of the engine nacelle, a sound source for high-frequency components of jet noise at a position at which the shield is capable of shielding the high-frequency components of jet noise due to the engine exhaust flow, to thereby reduce the high-frequency components of jet noise; and
promoting mixing of low-frequency components of jet noise due to the engine exhaust flow with an external air flow to thereby reduce je-noise having-the low-frequency components of jet noise,
wherein the exhaust nozzle extends to the rear of the jet engine and constitutes an exhaust flow path,
wherein the exhaust nozzle has a plurality of main nozzle pieces and at least one coupling nozzle piece,
wherein a rear end portion of each of the main nozzle pieces is provided swingably in an

Assignees

• Japan Aerospace Exploration

Inventors

• Akatsuka Junichi

Classifications

• F02K1/12

  by means of pivoted flaps · CPC title

• F02K1/46

  Nozzles having means for adding air to the jet or for augmenting the mixing region between the jet and the ambient air, e.g. for silencing (F02K1/28, F02K1/36, F02K1/38 take precedence) · CPC title

• F02K1/42

  the means being movable into an inoperative position · CPC title

• B64C5/02

  Tailplanes · CPC title

• F05D2220/80

  in supersonic vehicles excluding hypersonic vehicles or ram, scram or rocket propulsion · CPC title