US-12623786-B2 - Aircraft with boundary layer ingestion device having center position between center position of fuselage and center position of rear end portion of fuselage

US12623786B2US 12623786 B2US12623786 B2US 12623786B2US-12623786-B2

Abstract

An aircraft according to the present technology includes: a fuselage section; and a BLI propulsion section. The fuselage section has a cylindrical shape that is long in an axial direction and short in a width direction and a vertical direction, and includes a rear end portion on a rear side in the axial direction. The BLI propulsion section is a BLI propulsion section that is provided on a rear side of the fuselage section and includes an intake port, a center position of the intake port being offset from a center position of the rear end portion in at least one of the vertical direction or the width direction.

Inventors

Hiroshi Kobayashi
Yuzuru Yokokawa
Masayuki Suzuki
Akira Nishizawa
Ryuji Iijima
Eiji Shima

Assignees

JAPAN AEROSPACE EXPLORATION AGENCY

Dates

Publication Date: 20260512
Application Date: 20221012
Priority Date: 20211026

Claims (16)

1 . An aircraft, comprising: a fuselage section that has a cylindrical shape with a first predetermined length in an axial direction and a second predetermined length in a width direction and a vertical direction, and includes a rear end portion on a rear side in the axial direction, wherein the first predetermined length is longer than the second predetermined length, wherein the fuselage section has a shape in which an outer diameter gradually decreases toward the rear end portion on the rear side, wherein a center position of the rear end portion is located above a center position of the fuselage section at a position corresponding to a maximum diameter of the fuselage section in the vertical direction; and a boundary layer ingestion (BLI) propulsion device that is provided on the rear side of the fuselage section and includes an intake port, wherein a center position of the intake port is located between the center position of the fuselage section and the center position of the rear end portion in the vertical direction, and wherein the center position of the intake port is offset below the center position of the rear end portion in the vertical direction, wherein the BLI propulsion device includes at least one impeller that is rotatable with an axis directed in the axial direction as a central axis, and wherein a position of the central axis is offset above the center position of the intake port in the vertical direction.
2 . The aircraft according to claim 1 , wherein a non-overlapping region exists where a region corresponding to the maximum diameter of the fuselage section and a region corresponding to the intake port do not overlap with each other when the maximum diameter of the fuselage section and the intake port are viewed from the axial direction, and wherein an area of the non-overlapping region occupies less than 60%.
3 . The aircraft according to claim 1 , wherein a value of AR is 1.3 or more, AR being represented by (2a) 2 /Sfan, 2a being a length of the intake port in the width direction, Sfan being an area of the intake port.
4 . The aircraft according to claim 1 , wherein the at least one impeller includes a first impeller and a second impeller aligned in the width direction, and wherein a rotation direction of the first impeller and a rotation direction of the second impeller are in opposite directions.
5 . The aircraft according to claim 4 , wherein the rotation direction of each of the first impeller and the second impeller is a rotation direction corresponding to inboard-up rotation.
6 . The aircraft according to claim 1 , wherein the at least one impeller has a central axis of rotation located outside the center position of the intake port in the width direction.
7 . The aircraft according to claim 1 , further comprising: a landing section provided below the fuselage section; and an angle formed between the axial direction and a tangent connecting a ground contact point of the landing section and the lowest point of the BLI propulsion device when the fuselage section and the landing section are viewed from the width direction, wherein the angle exceeds 10.5°.
8 . The aircraft according to claim 1 , wherein the intake port is disposed behind a position where a width of the fuselage section is 50% of a maximum value of the width of the fuselage section in the axial direction.
9 . The aircraft according to claim 1 , wherein a position of the BLI propulsion device corresponding to the center position of the intake port is not joined to the fuselage section.
10 . The aircraft according to claim 1 , wherein the intake port is disposed behind a position where a cross-sectional area of the fuselage section perpendicular to the axial direction is 25% of a maximum value of the cross-sectional area in the axial direction.
11 . The aircraft according to claim 1 , further comprising: a main engine section that includes a generator, the BLI propulsion device being driven by electric power from the generator.
12 . The aircraft according to claim 11 , wherein the generator is operated at an extracted torque within a range of 90% to 100% of a maximum torque of the generator, regardless of an operating state of the aircraft.
13 . The aircraft according to claim 11 , wherein power extracted from the generator is limited to a predetermined value or less in a case where at least one of a condition that an altitude of the aircraft is a predetermined altitude or less and a condition that speed of the aircraft is a predetermined speed or less is satisfied.
14 . The aircraft according to claim 13 , wherein the main engine section includes a plurality of main engines each including the generator, and wherein power extracted from the generator is limited to a predetermined value or less in a case where a condition that at least one of the plurality of main engines has stopped is satisfied in addition to a condition that the at least one of the two conditions is satisfied.
15 . The aircraft according to claim 11 , wherein the main engine section includes an engine shaft that rotates to cause the generator to generate electric power, and wherein an extracted torque extracted from the generator is limited to 10% or less of a maximum value of the extracted torque in a case where a rotation speed of the engine shaft of the main engine section is 60% or less of a maximum rotation speed of the engine shaft.
16 . The aircraft according to claim 11 , wherein an extracted torque extracted from the generator is limited to 10% or less of a maximum value of the extracted torque in a case where an engine output of the main engine section, when the aircraft flies at a predetermined altitude, is 60% or less of a maximum value of the engine output the predetermined altitude.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. national stage application of International Patent Application No. PCT/JP2022/038038, filed Oct. 12, 2022, which claims the benefit under 35 U.S.C. § 119 of Japanese Application No. 2021-174711, filed Oct. 26, 2021, the disclosures of each of which are incorporated herein by reference in their entirety. TECHNICAL FIELD The present invention relates to a technology for an aircraft that includes a BLI propulsion device on its rear side, and the like. BACKGROUND ART In recent years, a device called a BLI propulsion device (BLI: Boundary Layer Ingestion) has become known as a type of propulsion device that generates thrust in an aircraft (see the following Non-Patent Literature 1). The BLI propulsion device takes in slow airflow near the surface of the aircraft, and accelerates and discharges the taken-in airflow backwards, thereby generating thrust in the travelling direction of the aircraft. The BLI technology is a technology based on the viewpoint that it is more efficient to accelerate slow airflow to obtain thrust than to further accelerate fast airflow to obtain thrust. CITATION LIST Non-Patent Literature Non-Patent Literature 1 Modeling Boundary Layer Ingestion Using a Coupled Aeropropulsive Analysis” JOURNAL OF AIRCRAFT Vol. 55, No. 3, May-June 2018 DISCLOSURE OF INVENTION Technical Problem In the BLI propulsion technology, there is a demand for a technology capable of improving propulsion efficiency. In view of the circumstances as described above, it is an object of the present technology to provide a technology capable of improving propulsion efficiency in the BLI propulsion technology. Solution to Problem In order to achieve the above-mentioned object, an aircraft according to the present technology includes: a fuselage section; and a BLI propulsion section. The fuselage section has a cylindrical shape that is long in an axial direction and short in a width direction and a vertical direction, and includes a rear end portion on a rear side in the axial direction. The BLI propulsion section is a BLI propulsion section that is provided on a rear side of the fuselage section and includes an intake port, a center position of the intake port being offset from a center position of the rear end portion in at least one of the vertical direction or the width direction. By causing the center position of the intake port to be offset from the center position of the rear end portion of the fuselage section, it is possible to efficiently take in slow airflow from the intake port, thereby improving propulsion efficiency. In the aircraft, the fuselage section may have a shape in which an outer diameter gradually decreases toward the rear end portion on the read side of the fuselage section. In the aircraft, the center position of the rear end portion may be located above a center position of the fuselage section in the vertical direction. In the aircraft, the center position of the intake port may be offset below the center position of the rear end portion in the vertical direction. In the aircraft, the center position of the intake port may be located between the center position of the fuselage section and the center position of the rear end portion in the vertical direction. In the aircraft, an area of a non-overlapping region where a projection plane when parallel light parallel to the axial direction is applied to the fuselage section and a projection plane when the parallel light is applied to the intake port do not overlap with each other may occupy less than 60% In the aircraft, a value of AR may be 1.3 or more, AR being represented by (2a)2/Sfan, 2a being a length of the intake port in the width direction, Sfan being an area of the intake port. In the aircraft, the BLI propulsion section may include at least one blade section that is rotatable with an axis directed in the axial direction as a central axis. In the aircraft, the BLI propulsion section may include a first impeller and a second impeller aligned in the width direction, a rotation direction of the first impeller and a rotation direction of the second impeller are in opposite directions. In the aircraft, the rotation direction of each of the first impeller and the second impeller may be a rotation direction corresponding to inboard-up rotation. In the aircraft, the BLI propulsion section may include a third impeller that is located between the first impeller and the second impeller in the width direction and below the first impeller and the second impeller in the vertical direction. In the aircraft, the impeller may have a central axis of rotation located above the center position of the intake port in the vertical direction. In the aircraft, the impeller may have a central axis of rotation located outside the center position of the intake port in the width direction. The aircraft may further include a landing section provided below the fuselage section, an angle formed between th