The present subject matter relates generally to an aircraft propulsion system including an aft engine.
A conventional commercial aircraft generally includes a fuselage, a pair of wings, and a propulsion system that provides thrust. The propulsion system typically includes at least two aircraft engines, such as turbofan jet engines. Each turbofan jet engine is mounted to a respective one of the wings of the aircraft, such as in a suspended position beneath the wing, separated from the wing and fuselage. Such a configuration allows for the turbofan jet engines to interact with separate, freestream airflows that are not impacted by the wings and/or fuselage. This configuration can reduce an amount of turbulence within the air entering an inlet of each respective turbofan jet engine, which has a positive effect on a net propulsive thrust of the aircraft.
However, a drag on the aircraft including the turbofan jet engines, also has an effect on the net propulsive thrust of the aircraft. A total amount of drag on the aircraft, including skin friction, form, and induced drag, is generally proportional to a difference between a freestream velocity of air approaching the aircraft and an average velocity of a wake downstream from the aircraft that is produced due to the drag on the aircraft.
Systems have been proposed to counter the effects of drag and/or to improve an efficiency of the turbofan jet engines. For example, certain propulsion systems incorporate boundary layer ingestion systems to route a portion of relatively slow moving air forming a boundary layer across, e.g., the fuselage and/or the wings, into the turbofan jet engines upstream from a fan section of the turbofan jet engines. Although this configuration can reduce drag by reenergizing the boundary layer airflow downstream from the aircraft, the relatively slow moving flow of air from the boundary layer entering the turbofan jet engine generally has a nonuniform or distorted velocity profile. As a result, such turbofan jet engines can experience an efficiency loss minimizing or negating any benefits of reduced drag on the aircraft.
Accordingly, a propulsion system including one or more components for reducing an amount of drag on the aircraft would be useful. More particularly, a propulsion system including one or more components for reducing an amount of drag on the aircraft without causing any substantial decreases in an efficiency of the aircraft engines would be especially beneficial.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one exemplary embodiment of the present disclosure, a propulsion system for an aircraft having a fuselage is provided. The propulsion system includes an aft engine configured to be mounted to the aircraft at an aft end of the aircraft. The aft engine defines a central axis and includes a fan rotatable about the central axis, the fan having a plurality of fan blades. The aft engine also includes a nacelle encircling the fan and extending around the mean line of the aircraft at the aft end of the aircraft when the aft engine is mounted to the aircraft. The aft engine also includes one or more structural members extending between the nacelle and the fuselage of the aircraft at a location forward of the plurality of fan blades when the aft engine is mounted to the aircraft.
In another exemplary embodiment of the present disclosure, a boundary layer ingestion fan for mounting to an aircraft at an aft end of the aircraft is provided. The boundary layer ingestion fan includes a fan rotatable about a central axis of the boundary layer ingestion fan and including a plurality of fan blades. The boundary layer ingestion fan also includes a nacelle encircling the plurality of fan blades of the fan. The nacelle also defines an inlet with the fuselage of the aircraft and extends substantially around the fuselage of the aircraft when the boundary layer ingestion fan is mounted at the aft end of the aircraft. The boundary layer ingestion fan also includes one or more structural members attached to the nacelle at a location forward of the plurality of fan blades of the fan for mounting the boundary layer ingestion fan to the aircraft.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.
Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,
Moreover, the aircraft 10 includes a fuselage 12, extending longitudinally from the forward end 16 of the aircraft 10 towards the aft end 18 of the aircraft 10, and a pair of wings 20. As used herein, the term “fuselage” generally includes all of the body of the aircraft 10, such as an empennage of the aircraft 10. The first of such wings 20 extends laterally outwardly with respect to the longitudinal centerline 14 from a port side 22 of the fuselage 12 and the second of such wings 20 extends laterally outwardly with respect to the longitudinal centerline 14 from a starboard side 24 of the fuselage 12. Each of the wings 20 for the exemplary embodiment depicted includes one or more leading edge flaps 26 and one or more trailing edge flaps 28. The aircraft 10 further includes a vertical stabilizer 30 having a rudder flap 32 for yaw control, and a pair of horizontal stabilizers 34, each having an elevator flap 36 for pitch control. The fuselage 12 additionally includes an outer surface or skin 38. It should be appreciated however, that in other exemplary embodiments of the present disclosure, the aircraft 10 may additionally or alternatively include any other suitable configuration of stabilizer that may or may not extend directly along the vertical direction V or horizontal/lateral direction L.
The exemplary aircraft 10 of
In various embodiments, the jet engines 102, 104 may be configured to provide power to an electric generator 108 and/or an energy storage device 110. For example, one or both of the jet engines 102, 104 may be configured to provide mechanical power from a rotating shaft (such as an LP shaft or HP shaft) to the electric generator 108. Additionally, the electric generator 108 may be configured to convert the mechanical power to electrical power and provide such electrical power to one or both of the energy storage device 110 or the BLI fan 106. Accordingly, in such an embodiment, the propulsion system 100 may be referred to as a gas-electric propulsion system. It should be appreciated, however, that the aircraft 10 and propulsion system 100 depicted in
Referring now to
The exemplary core turbine engine 204 depicted generally includes a substantially tubular outer casing 206 that defines an annular inlet 208. The outer casing 206 encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor 210 and a high pressure (HP) compressor 212; a combustion section 214; a turbine section including a high pressure (HP) turbine 216 and a low pressure (LP) turbine 218; and a jet exhaust nozzle section 220. A high pressure (HP) shaft or spool 222 drivingly connects the HP turbine 216 to the HP compressor 212. A low pressure (LP) shaft or spool 224 drivingly connects the LP turbine 218 to the LP compressor 210.
For the embodiment depicted, the fan section 202 includes a variable pitch fan 226 having a plurality of fan blades 228 coupled to a disk 230 in a spaced apart manner. As depicted, the fan blades 228 extend outwardly from disk 230 generally along the radial direction R1. Each fan blade 228 is rotatable relative to the disk 230 about a pitch axis P by virtue of the fan blades 228 being operatively coupled to a suitable actuation member 232 configured to collectively vary the pitch of the fan blades 228 in unison. The fan blades 228, disk 230, and actuation member 232 are together rotatable about the longitudinal axis 12 by LP shaft 224 across a power gear box 234. The power gear box 234 includes a plurality of gears for stepping down the rotational speed of the LP shaft 224 to a more efficient rotational fan speed.
Referring still to the exemplary embodiment of
It should be appreciated, however, that the exemplary turbofan engine 200 depicted in
Referring now to
As shown in
In general, the BLI fan 300 includes a fan 304 rotatable about the centerline axis 302, a nacelle 306 extending around a portion of the fan 304, and one or more structural members 308 extending between the nacelle 306 and the fuselage 12 of the aircraft 10. More specifically, the fan 304 includes a plurality of fan blades 310 spaced generally along the circumferential direction C2, and the one or more structural members 308 extend between the nacelle 306 and the fuselage 12 of the aircraft 10 at a location forward of the plurality of fan blades 310. Further, the nacelle 306 extends around and encircles the plurality of fan blades 310, and also extends around the fuselage 12 of the aircraft 10 and the mean line 15 of the aircraft 10 at an aft end 18 of the aircraft 10 when, as in
As is also depicted in
In certain exemplary embodiments, the plurality of fan blades 310 may be attached in a fixed manner to the fan shaft 312, or alternatively, the plurality of fan blades 310 may be rotatably attached to the fan shaft 312. For example, the plurality of fan blades 310 may be attached to the fan shaft 312 such that a pitch of each of the plurality of fan blades 310 may be changed, e.g., in unison, by a pitch change mechanism (not shown). Changing the pitch of the plurality of fan blades 310 may increase an efficiency of the BLI fan 300 and/or may allow the BLI fan 300 to achieve a desired thrust profile. With such an exemplary embodiment, the BLI fan 300 may be referred to as a variable pitch BLI fan.
The fan shaft 312 is mechanically coupled to a power source 314 located at least partially within the fuselage 12 of the aircraft 10, forward of the plurality of fan blades 310. For the embodiment depicted, the fan shaft 312 is mechanically coupled to the power source 314 through a gearbox 316. The gearbox 316 may be configured to modify a rotational speed of the power source 314, or rather of a shaft 315 of the power source 314, such that the fan 304 of the BLI fan 300 rotates at a desired rotational speed. The gearbox 316 may be a fixed ratio gearbox, or alternatively, the gearbox 316 may define a variable gear ratio. With such an embodiment, the gearbox 316 may be operably connected to, e.g., a controller of the aircraft 10 for changing its ratio in response to one or more flight conditions.
In certain exemplary embodiments, the BLI fan 300 may be configured with a gas-electric propulsion system, such as the gas-electric propulsion system 100 described above with reference to
As briefly stated above, the BLI fan 300 includes one or more structural members 308 for mounting the BLI fan 300 to the aircraft 10. The one or more structural members 308 for the embodiment depicted extend substantially along the radial direction R2 of the BLI fan 300 between the nacelle 306 and the fuselage 12 of the aircraft 10 for mounting the BLI fan 300 to the fuselage 12 of the aircraft 10. It should be appreciated, that as used herein, terms of approximation, such as “approximately,” “substantially,” or “about,” refer to being within a ten percent margin of error.
Additionally, for the embodiment depicted, the one or more structural members 308 are configured as inlet guide vanes for the fan 304. Specifically, the one or more structural members 308 are shaped and oriented to direct and condition a flow of air into the BLI fan 300 to, e.g., increase an efficiency of the BLI fan 300, or reduce a distortion of the air flowing into the BLI fan 300.
In certain exemplary embodiments, the one or more structural members 308 may be configured as fixed inlet guide vanes extending between the nacelle 306 and the fuselage 12 of the aircraft 10. However, for the embodiment depicted, the one or more structural members 308 are configured as variable inlet guide vanes. Referring now also to
Referring still to
Referring still to
Aft of the plurality of fan blades 310, and for the embodiment depicted, aft of the one or more outlet guide vanes 338, the BLI fan 300 additionally defines a nozzle 342 between the nacelle 306 and the tail cone 340. The nozzle 342 may be configured to generate an amount of trust from the air flowing therethrough, and the tail cone 340 may be shaped to minimize an amount of drag on the BLI fan 300. However, in other embodiments, the tail cone 340 may have any other shape and may, e.g., end forward of an aft end of the nacelle 306 such that the tail cone 340 is enclosed by the nacelle 306 at an aft end. Additionally, in other embodiments, the BLI fan 300 may not be configured to generate any measurable amount of thrust, and instead may be configured to ingest air from a boundary layer of air of the fuselage 12 of the aircraft 10 and add energy/speed up such air to reduce an overall drag on the aircraft 10 (and thus increase a net thrust of the aircraft 10).
Referring now to
Referring specifically to
Similarly, referring now to the exemplary BLI fan 300 of
Referring now to
As is depicted, for the embodiment of
Referring now to
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Number | Name | Date | Kind |
---|---|---|---|
2477637 | Mercier | Aug 1949 | A |
2812912 | Stevens et al. | Nov 1957 | A |
2918229 | Lippisch | Dec 1959 | A |
3194516 | Messerschmitt | Jul 1965 | A |
3286470 | Gerlaugh | Nov 1966 | A |
3289975 | Hall | Dec 1966 | A |
3312448 | Hull, Jr. et al. | Apr 1967 | A |
3844110 | Widlansky et al. | Oct 1974 | A |
4089493 | Paulson | May 1978 | A |
4371133 | Edgley | Feb 1983 | A |
4605185 | Reyes | Aug 1986 | A |
4722357 | Wynosky | Feb 1988 | A |
4913380 | Verdaman et al. | Apr 1990 | A |
5721402 | Parente | Feb 1998 | A |
5927644 | Ellis et al. | Jul 1999 | A |
6089505 | Gruensfelder et al. | Jul 2000 | A |
6976655 | Thompson | Dec 2005 | B2 |
7387189 | James et al. | Jun 2008 | B2 |
7493754 | Moniz et al. | Feb 2009 | B2 |
7665689 | McComb | Feb 2010 | B2 |
7806363 | Udall et al. | Oct 2010 | B2 |
7819358 | Belleville | Oct 2010 | B2 |
7905449 | Cazals et al. | Mar 2011 | B2 |
7976273 | Suciu et al. | Jul 2011 | B2 |
8033094 | Suciu et al. | Oct 2011 | B2 |
8099944 | Foster et al. | Jan 2012 | B2 |
8109073 | Foster et al. | Feb 2012 | B2 |
8162254 | Roche | Apr 2012 | B2 |
8181900 | Chene et al. | May 2012 | B2 |
8220739 | Cazals | Jul 2012 | B2 |
8226040 | Neto | Jul 2012 | B2 |
8291716 | Foster et al. | Oct 2012 | B2 |
8317126 | Harris et al. | Nov 2012 | B2 |
8469306 | Kuhn, Jr. | Jun 2013 | B2 |
8544793 | Shammoh | Oct 2013 | B1 |
8549833 | Hyde et al. | Oct 2013 | B2 |
8596036 | Hyde et al. | Dec 2013 | B2 |
8640439 | Hoffjann et al. | Feb 2014 | B2 |
8672263 | Stolte | Mar 2014 | B2 |
8684304 | Burns et al. | Apr 2014 | B2 |
8857191 | Hyde et al. | Oct 2014 | B2 |
8890343 | Bulin et al. | Nov 2014 | B2 |
8939399 | Kouros et al. | Jan 2015 | B2 |
8998580 | Quiroz-Hernandez | Apr 2015 | B2 |
9038398 | Suciu et al. | May 2015 | B2 |
20060011779 | Cazals et al. | Jan 2006 | A1 |
20080023590 | Merrill et al. | Jan 2008 | A1 |
20090127384 | Voorhees | May 2009 | A1 |
20100038473 | Schneider et al. | Feb 2010 | A1 |
20100294882 | Gantie et al. | Nov 2010 | A1 |
20110215204 | Evulet | Sep 2011 | A1 |
20120006935 | Bhargava | Jan 2012 | A1 |
20120076635 | Atassi | Mar 2012 | A1 |
20120119020 | Burns et al. | May 2012 | A1 |
20120138736 | Cazals et al. | Jun 2012 | A1 |
20120153076 | Burns et al. | Jun 2012 | A1 |
20120209456 | Harmon et al. | Aug 2012 | A1 |
20130032215 | Streifinger | Feb 2013 | A1 |
20130036730 | Bruno et al. | Feb 2013 | A1 |
20130052005 | Cloft | Feb 2013 | A1 |
20130099065 | Stuhlberger | Apr 2013 | A1 |
20130139515 | Schlak | Jun 2013 | A1 |
20130184958 | Dyrla et al. | Jul 2013 | A1 |
20130199624 | Smith et al. | Aug 2013 | A1 |
20130227950 | Anderson et al. | Sep 2013 | A1 |
20130251525 | Saiz | Sep 2013 | A1 |
20130284279 | Richards | Oct 2013 | A1 |
20130336781 | Rolt et al. | Dec 2013 | A1 |
20140010652 | Suntharalingam et al. | Jan 2014 | A1 |
20140060995 | Anderson et al. | Mar 2014 | A1 |
20140151495 | Kuhn, Jr. | Jun 2014 | A1 |
20140179535 | Stuckl et al. | Jun 2014 | A1 |
20140212279 | Boudebiza et al. | Jul 2014 | A1 |
20140250861 | Eames | Sep 2014 | A1 |
20140283519 | Mariotto et al. | Sep 2014 | A1 |
20140290208 | Rechain et al. | Oct 2014 | A1 |
20140339371 | Yates et al. | Nov 2014 | A1 |
20140345281 | Galbraith | Nov 2014 | A1 |
20140346283 | Salyer | Nov 2014 | A1 |
20140367510 | Viala et al. | Dec 2014 | A1 |
20140367525 | Salyer | Dec 2014 | A1 |
20140369810 | Binks et al. | Dec 2014 | A1 |
20150013306 | Shelley | Jan 2015 | A1 |
20150028594 | Mariotto | Jan 2015 | A1 |
20150285144 | Todorovic et al. | Oct 2015 | A1 |
20150291285 | Gallet | Oct 2015 | A1 |
Number | Date | Country |
---|---|---|
0887259 | Dec 1998 | EP |
1616786 | Jan 2006 | EP |
2730501 | May 2014 | EP |
3048042 | Jul 2016 | EP |
3093235 | Nov 2016 | EP |
1181456 | Jun 1959 | FR |
2993859 | Jan 2014 | FR |
406713 | Feb 1934 | GB |
2489311 | Sep 2012 | GB |
WO 2010020199 | Feb 2010 | WO |
2010103252 | Sep 2010 | WO |
WO 2014072615 | May 2014 | WO |
Entry |
---|
European Search Report and Opinion issued in connection with corresponding EP Application No. 16192467.5 dated Feb. 15, 2017. |
http://aviationweek.com/awin/boeing-researches-alternative-propulsion-and-fuel-options, Aviation Week & Space Technology, Jun. 4, 2012. |
Bradley et al., “Subsonic Ultra Green Aircraft Research, Phase II: N+4 Advanced Concept Development,” NASA/CR-2012-217556, May 2012. |
European Search Report and Opinion issued in connection with corresponding EP Application No. 16188786.4 dated Nov. 16, 2016. |
“Concept Study Propulsive Fuselage: Adding an Extra Engine to Reduce Emissions”, Bauhaus Luftfahrt, 02 Pages, May 20, 2014. |
Notice of Allowance issued in connection with Related U.S. Appl. No. 14/859,549 dated Jan. 5, 2017. |
U.S. Non-Final Office Action issued in connection with Related U.S. Appl. No. 14/859,566 dated Feb. 1, 2017. |
Boeing 737, “https://en.wikipedia.org/wiki/Boeing—737”, Retrieved on Feb. 4, 2017. |
U.S. Non-Final Office Action issued in connection with Related U.S. Appl. No. 14/859,523 dated Feb. 9, 2017. |
U.S. Non-Final Office Action issued in connection with Related U.S. Appl. No. 14/859,556 dated Feb. 9, 2017. |
European Search Report and Opinion issued in connection with Related EP Application No. 16188826.8 dated Feb. 15, 2017. |
European Search Report and Opinion issued in connection with Related EP Application No. 16188994.4 dated Feb. 17, 2017. |
European Search Report and Opinion issued in connection with Related EP Application No. 16188464.8 dated Feb. 17, 2017. |
Final Office Action issued in connection with Related U.S. Appl. No. 14/859,566 dated May 11, 2017. |
GE Related Case Form. |
US Notice of Allowance issued in connection with related U.S. Appl. No. 14/859,566 on Jul. 14, 2017. |
Number | Date | Country | |
---|---|---|---|
20170081035 A1 | Mar 2017 | US |