674:. The second turbine acts as the propulsion unit. The turbogenerator powers an electric motor that controls the compressor of the second turbine. The motor can change speeds to keep the fan turning at the ideal RPM for a specific flight mode. In turbojet and ramjet modes, the inlet is narrowed to compress the air and eliminate bypass. The turbogenerator is commercially available, while the propulsion unit is built by the company. A key innovation is that electric motors have dramatically increased their power density so that the weight of the motor is no longer prohibitive.
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core. Only bypass air passes through the fan. The LP compressor exit flow passes through passages within the fan disc, directly underneath the fan blades. Some bypass air enters the engine via an auxiliary intake. During take-off and approach the engine behaves much like a conventional turbofan, with
594:
In the mixed-flow turbofan with ejector concept, a low bypass ratio engine is mounted in front of a long tube, called an ejector. The ejector reduces noise. It is deployed during take-off and approach. Turbofan exhaust gases send air into the ejector via an auxiliary air intake, thereby reducing the
554:, skipping the rear fan. Intakes on each side of the engine open to capture air and send it directly to the rear fan and the rest of the engine. Parallel mode substantially increases the total air accelerated by the engine, lowering the velocity of the air and accompanying noise.
539:
One SST VCE concept is the tandem fan engine. The engine has two fans, both mounted on the low-pressure shaft, separated by a significant axial gap. The engine operates in series mode while cruising and parallel mode take-off, climb-out, approach, and final-descent.
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fighter aircraft competition, in the late 1980s. GE used a double bypass/hybrid fan arrangement, but never disclosed how they exploited the concept. The Air Force instead selected the conventional
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is required or through the core for greater power. Under the
Versatile Affordable Advanced Turbine Engines (VAATE) program, the U.S Air Force and industry partners developed this concept under the
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to use a tandem fan configuration and successfully demonstrated the switch from series to parallel operation (and vice versa) with the engine running, albeit at partial power.
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In series mode, air enters in the front of the engine. After passing through the front fan, the air passes directly into the second fan, so that the engine behaves much like a
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222:(net thrust/airflow) to minimize the powerplant's cross-sectional area. This implies a high jet velocity supersonic cruise and at take-off, which makes the aircraft noisy.
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had a high specific thrust in supersonic cruise and at dry take-off. This made the engines noisy. The problem was compounded by the need for a modest amount of
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611:(ADVENT) and the follow-on Adaptive Engine Technology Demonstrator (AETD) and Adaptive Engine Transition Program (AETP) programs. Examples include the
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specific thrust/mean jet velocity of the final exhaust. The mixed-flow design is not particularly efficient at low speed, but is considerably simpler.
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In the mid-tandem fan concept, a high specific flow single stage fan is located between the high pressure (HP) and low pressure (LP) compressors of a
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Startup Astro
Mechanica is developing what it calls a turboelectric-adaptive jet engine that shifts from turbofan to turbojet to
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A high specific thrust engine has a high jet velocity by definition, as implied by the approximate equation for net thrust:
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In parallel mode, air leaving the front fan exits the engine through an auxiliary nozzle on the underside of the
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737:
Versatile
Affordable Advanced Turbine Engines Provide Game Changing Capability with Superior Fuel Efficiency
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743:. 11th Annual Science & Engineering Technology Conference/DoD Tech Expo. Charleston, South Carolina.
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The three-stream architecture adds a third, directable air stream. This stream bypasses the core when
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So for zero flight velocity, specific thrust is directly proportional to jet velocity.
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Aircraft propulsion system efficient at a range of speeds higher and lower than sound's
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301:{\displaystyle F_{\text{n}}={\dot {m}}\left(V_{\text{jfe}}-V_{\text{a}}\right)}
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that is designed to operate efficiently under mixed flight conditions, such as
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670:. This is achieved by using a dual turbine approach. One turbine acts as an
501:{\displaystyle {\frac {F_{\text{n}}}{\dot {m}}}=V_{\text{jfe}}-V_{\text{a}}}
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an acceptable jet noise level (i.e., low specific thrust). However, for
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mode as it accelerates from a standing start to a projected
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developed a variable cycle engine, known as the GE37 or
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Rearranging the equation, specific thrust is given by:
210:(SST) may require some form of VCE. To reduce aircraft
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526:(reheat) at take-off (and transonic acceleration).
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99:. Unsourced material may be challenged and removed.
1248:Engine-indicating and crew-alerting system (EICAS)
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401:fully expanded jet velocity (in the exhaust plume)
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360:
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1281:Full Authority Digital Engine/Electronics (FADEC)
1238:Electronic centralised aircraft monitor (ECAM)
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862:
8:
175:Cut-away view of a prospective ADVENT engine
619:, as well as the propulsion system for the
361:{\textstyle {\dot {m}}={\frac {d}{dt}}m,\,}
43:It has been suggested that this article be
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1243:Electronic flight instrument system (EFIS)
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782:"Astro Mechanica - The Aerospace Company"
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159:Learn how and when to remove this message
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805:Keil, Christian (February 28, 2024).
7:
734:Thomson, Daniel E. (14 April 2010).
609:Adaptive Versatile Engine Technology
97:adding citations to reliable sources
1524:Timeline of heat engine technology
824:Côté, Andrew (February 28, 2024).
780:McCormick, Packy (April 1, 2024).
25:
394:{\displaystyle V_{\text{jfe}},\,}
1111:Thrust specific fuel consumption
73:
34:
427:{\displaystyle V_{\text{a}},\,}
84:needs additional citations for
1160:Propeller speed reduction unit
516:Rolls-Royce/Snecma Olympus 593
1:
754:Mathews, Jim (26 June 2017).
621:Next Generation Air Dominance
218:, SST engines require a high
1071:Engine pressure ratio (EPR)
807:"Interview with Ian Brooke"
652:Lockheed Martin F-22 Raptor
590:Mixed-flow turbofan ejector
185:adaptive cycle engine (ACE)
181:variable cycle engine (VCE)
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1338:Auxiliary power unit (APU)
967:Rotating detonation engine
689:Advanced Technology Engine
684:Index of aviation articles
50:Advanced technology engine
1532:
1519:
1501:
1401:
617:Pratt & Whitney XA101
1046:Aircraft engine starting
648:Pratt & Whitney F119
563:Pratt & Whitney JT8D
434:aircraft flight velocity
60:Proposed since May 2024.
927:Pulse detonation engine
756:"Engines of Innovation"
206:The next generation of
108:"Variable cycle engine"
1116:Thrust to weight ratio
1086:Overall pressure ratio
1081:Jet engine performance
1005:Centrifugal compressor
922:Gluhareff Pressure Jet
636:General Electric YF120
613:General Electric XA100
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183:, also referred to as
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1466:Steam (reciprocating)
1353:Ice protection system
1121:Variable cycle engine
1091:Propulsive efficiency
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368:intake mass flow rate
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18:Adaptive cycle engine
1253:Flight data recorder
1015:Constant speed drive
995:Afterburner (reheat)
650:for what became the
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208:supersonic transport
93:improve this article
1535:Thermodynamic cycle
1446:Pistonless (Rotary)
1436:Photo-Carnot engine
1155:Propeller governor
760:Air Force Magazine
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1233:Annunciator panel
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1025:Propelling nozzle
826:"Astro Mechanica"
715:on 23 August 2006
709:"Thrust equation"
580:supersonic cruise
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16:(Redirected from
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1348:Hydraulic system
1343:Bleed air system
1333:Air-start system
1196:Counter-rotating
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1126:Windmill restart
1096:Specific impulse
1066:Compressor stall
1000:Axial compressor
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786:www.notboring.co
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711:. Archived from
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632:General Electric
623:(NGAD) fighter.
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1291:Thrust reversal
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605:fuel efficiency
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672:turbogenerator
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569:Mid-tandem fan
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557:In the 1970s,
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149:September 2009
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1258:Glass cockpit
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1056:Brayton cycle
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1030:Turbine blade
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627:Double bypass
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110: –
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104:Find sources:
98:
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82:This article
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52:
51:
46:
41:
32:
31:
19:
1506:Beale number
1461:Split-single
1395:Heat engines
1312:Flame holder
1286:Thrust lever
1276:Autothrottle
1120:
1106:Thrust lapse
1061:Bypass ratio
893:Gas turbines
885:gas turbines
833:. Retrieved
829:
819:
810:
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789:. Retrieved
785:
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763:. Retrieved
759:
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729:
717:. Retrieved
713:the original
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602:
599:Three stream
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524:afterburning
513:
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91:Please help
86:verification
83:
59:
48:
1559:Jet engines
1511:West number
1431:Minto wheel
1416:Gas turbine
1226:instruments
1181:Blade pitch
1176:Autofeather
878:Jet engines
561:modified a
216:supercruise
1548:Categories
1451:Rijke tube
1169:Principles
1148:Components
1140:Propellers
1039:Principles
990:Air intake
978:components
976:Mechanical
952:Turboshaft
791:2024-05-19
765:11 January
695:References
638:, for the
535:Tandem fan
201:supersonic
189:jet engine
119:newspapers
1554:Mechanics
1476:Aeolipile
1201:Proprotor
1051:Bleed air
1010:Combustor
947:Turboprop
486:−
466:˙
328:˙
281:−
260:˙
197:transonic
1483:Stirling
1411:Fluidyne
1317:Jet fuel
1206:Scimitar
1076:Flameout
1020:Impeller
942:Turbojet
937:Turbofan
918:Pulsejet
882:aircraft
835:April 2,
719:20 March
678:See also
615:and the
575:turbojet
545:turbofan
530:Concepts
520:Concorde
193:subsonic
1421:Hot air
1305:systems
932:Propfan
552:nacelle
311:where:
133:scholar
55:Discuss
1456:Rocket
1441:Piston
1224:Engine
1101:Thrust
962:Rocket
957:Ramjet
668:Mach 6
664:ramjet
559:Boeing
135:
128:
121:
114:
106:
45:merged
906:Types
830:x.com
811:x.com
741:(PDF)
644:YF-23
640:YF-22
140:JSTOR
126:books
47:with
1301:Fuel
896:and
880:and
837:2024
767:2020
721:2011
584:F404
514:The
212:drag
199:and
112:news
1426:Jet
586:).
547:.
518:in
481:jfe
383:jfe
276:jfe
214:at
95:by
53:. (
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828:.
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784:.
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203:.
195:,
179:A
1387:e
1380:t
1373:v
920:/
870:e
863:t
856:v
839:.
813:.
794:.
769:.
723:.
642:/
494:a
490:V
477:V
473:=
463:m
456:n
452:F
421:,
416:a
412:V
388:,
379:V
355:,
352:m
346:t
343:d
339:d
334:=
325:m
295:)
289:a
285:V
272:V
267:(
257:m
251:=
246:n
242:F
162:)
156:(
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147:(
137:·
130:·
123:·
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89:.
57:)
20:)
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