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General Electric GEnx

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GEnx
General Electric GEnx at the Paris Air Show 2009
Type Turbofan
Manufacturer GE Aviation
First run 2006
Major applications Boeing 747-8
Boeing 787 Dreamliner
Developed from General Electric GE90
Developed into CFM International LEAP-X

The General Electric GEnx (General Electric Next-generation) is an advanced dual rotor, axial flow, high-bypass turbofan jet engine in production by GE Aviation for the Boeing 787 and 747-8. The GEnx is intended to replace the CF6 in GE's product line.

Design and development

GEnx on 747-8I prototype

The GEnx and the Rolls-Royce Trent 1000 were selected by Boeing following a run-off between the three big engine manufacturers. The GEnx uses some technology from the GE90 turbofan, including composite fan blades, and the smaller core featured in earlier variants of the engine. The engine carries composite technology into the fan case.

Both engine types will have a standard interface with the aircraft, allowing any 787 to be fitted with either GE or RR engines at any time.[1][2] The engine market for the 787 is estimated at US$40 billion over the next 25 years. A first is the elimination of bleed air systems using high temperature/high pressure air from the propulsion engines to power aircraft systems such as the starting, air-conditioning and anti-ice systems. Both engines enable the move towards the More Electric Aircraft, that is, the concept of replacing previously hydraulic and pneumatic systems, with electrical ones to reduce weight, increase efficiency, and reduce maintenance requirements.

The GEnx is expected to produce thrust from 53,000 to 75,000 lbf (240 to 330 kN) with first tests commencing in 2006 and service entry by 2008 (delayed by 787 deliveries). Boeing predicts reduced fuel consumption of up to 20% and significantly quieter engines than current turbofans. A 66,500 lbf (296 kN) thrust version (GEnx-2B67) will be used on the 747-8. Unlike the initial version, for the 787, this version has a traditional bleed air system to power internal pneumatic and ventilation systems. It will also have a smaller overall diameter than the initial model to accommodate installation on the 747.

General Electric began initial test runs of the bleedless GEnx variant on 19 March 2006.[3] The first flight with one of these engines took place on 22 February 2007, using a Boeing 747-100, fitted with one GEnx engine in the number 2 (inboard left hand side) position.

Technical problems

In the summer of 2012; three engines suffered Low Pressure Turbine (LPT) failures; one was caused by an assembly problem, which led to inspections of all other engines then in service.[4]

Technology

Fan blades and inlet guide vanes of GEnx-2B
Detail of GEnx core

Despite being derived from the GE90, the GEnx features a number of weight-saving features:

  • Fan diameter of 111 in (2.8 m) for the 787-8 and 105 in (2.7 m) for the 747-8.
  • Composite fan blades with titanium leading edges.
  • Fan case of composite material which reduces weight and thermal expansion.
  • Titanium aluminide stage 6 and 7 low pressure turbine blades.

Fuel burn reduction technologies include:

  • Fan bypass ratio of 9.6:1, which also helps reduce noise.
  • High pressure compressor based on GE90-94B, with 23:1 pressure ratio and only 10 stages. Also, shrouded guide vanes reduce secondary flows.
  • Counter-rotating spools for the reaction turbines to reduce load on guide vanes.
  • Lean TAPS (twin annular premixed swirler) combustor to reduce environmentally-harmful emissions with improved airflow to prevent back flash.[5]

Among features to reduce maintenance cost and increase engine life are:

  • Spools with lower parts count achieved by using blisks in some stages and low blade counts in other stages and by using a low number of stages.
  • Internal engine temperatures reduced by using more efficient cooling techniques.
  • Debris extraction within the low pressure compressor guards high pressure compressor.

All of these yield a fuel burn said to be 15% better than GE's CF6-80C2 engines for widebody aircraft.

Applications

Specifications

Data from.[6][7]

This engine is a dual rotor, axial flow, high bypass ratio turbofan. The 10-stage high pressure compressor is driven clockwise (Aft Looking Forward) by a 2-stage high pressure turbine. The single stage fan and 4-stage low pressure compressor are driven counterclockwise (Aft Looking Forward) by a 7-stage low pressure turbine. The engine control system includes a Full Authority Digital Engine Control (FADEC), which has an aircraft connection for digital communication. An engine monitoring unit (EMU) provides vibration level signals to the aircraft.

Engine
Model 		Arrangement Performance Dimensions (inch) and Weight (lb) Certified
(FAA) 		Application Entry Into Service Emissions
Fan
diameter
(in) 		Fan LPC HPC LPT HPT Thrust Max (lbf) Flat-Rated Temp C Overall
Pressure Ratio
(OPR) 		Fan
Bypass Ratio
(BPR) 		Air flow
(kg/s) 		SFC
(max power) 		T/W
Ratio 		Length Max Envelope Weight
(Dry) 		CO NOx HC
Take-off
(5 min) 		Max
Cont. 		Take-off Max
Cont. 		Width Height
GEnx-1B54 111 1 4 10 7 2 57,400 56,300 ISA+15 ISA+10 36.0     4.48 194.0 139.0 137.0 12,822 Mar 31, 2008 B787-3
GEnx-1B58 111 1 4 10 7 2 61,000 56,300 ISA+15 ISA+10     4.76 194.0 139.0 137.0 12,822 Mar 31, 2008 B787-3,-8
GEnx-1B64 111 1 4 10 7 2 67,500 61,500 ISA+15 ISA+10 41.0     5.23 194.0 139.0 137.0 12,822 Mar 31, 2008 B787-8,-9
GEnx-1B67 111 1 4 10 7 2 69,400 61,500 ISA+15 ISA+10 43.0     5.41 194.0 139.0 137.0 12,822 Mar 31, 2008 B787-8,-9
GEnx-1B70 111 1 4 10 7 2 72,300 66,500 ISA+15 ISA+10 43.0 9.6:1     5.64 194.0 139.0 137.0 12,822 Mar 31, 2008 B787-8,-9
GEnx-2B67 105 1 3 10 6 2 67,400 58,500     43.0 8.6:1     185.0 127.0 127.0 12,400 July 22, 2010 B747-8

Note: Data for sea level static, standard pressure, no customer bleed or customer horsepower extraction, ideal inlet, 100% ram recovery, production aircraft flight cowling, production instrumentation, fuel lower heating value of 18,400 BTU/lb.

Note: 787-3 plans were cancelled on December 13, 2010 due to low demand.[8]

Specifications (GEnx-1B64)

A GEnx-1B installed on a Boeing 787

Data from [9]

General characteristics

  • Type: Turbofan
  • Length: 4.98 m (196 in)
  • Diameter: 3.66 m (144 in)
  • Dry weight: 5,816 kg (12,822 lb)

Components

  • Compressor: Axial, 1 stage fan, 4 stage low pressure compressor, 10 stage high pressure compressor
  • Combustors: Annular
  • Turbine: Axial, 2 stage high pressure turbine, 7 stage low pressure turbine

Performance

See also

Related development

Comparable engines

Related lists

References

  1. ^ "Boeing 787 Aircraft Facts, Dates and History". Flightlevel350.com. Retrieved 2013-05-09.
  2. ^ "Boeing 787 Dreamliner Long-Range, Mid-Size Airliner". Aerospace Technology. Retrieved 2013-05-09.
  3. ^ "General Electric Performs First Run of New GEnx Engine." Flight International. 21 March 2006.
  4. ^ "GE identifies installation issue in GEnx, orders inspections". Flightglobal. Retrieved 6 October 2012.
  5. ^ GE website for TAPS combustor
  6. ^ FAA TCDS E00078NE
  7. ^ "GE plans mid-July nod for GEnx siblings." Flight International. 16 June 2010
  8. ^ "Boeing raises aircraft prices 5.2%, cancels short-haul 787". Seattle Times. 13 December 2010.
  9. ^ Gas Turbine Engines. Aviation Week & Space Technology Source Book 2009. p 118.
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