General Electric GEnx
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| GEnx | |
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| General Electric GEnx at the Paris Air Show 2009 | |
| Type | Turbofan |
| Manufacturer | GE Aviation |
| First run | 2000s |
| Major applications | Boeing 747-8 Boeing 787 |
| Developed from | General Electric GE90 |
The General Electric GEnx (General Electric Next-generation) is an advanced turbofan under development by GE Aviation for the Boeing 787 and 747-8. The GEnx is intended to replace the CF6 in GE's product line.
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[edit] Design and development
The GEnx and the Rolls-Royce Trent 1000 were selected by Boeing following a run-off between the three big engine manufacturers. Pratt & Whitney's proposal was not selected. The GEnx uses some technology from the GE90 turbofan, including composite fan blades. The engine carries composite technology into the fan case. General Electric has a 64% risk-sharing stake in the GEnx program. Other stakeholders include Ishikawajima-Harima Heavy Industries (IHI), 15%, and Avio, 12%. Volvo Aero, Techspace Aero, Mitsubishi Heavy Industries and Samsung Techwin hold the remaining 9%.
For the second time in commercial aviation, after the Airbus A380,[citation needed] 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. The engine market for the 787 is estimated at US$40 billion over the next 25 years. Another 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. The GEnx and the Trent 1000 allow a move towards the electric airplane.
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 (now 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.[1] 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 LH) position.
[edit] Technology
Despite being derived from the GE90, the GEnx features a number of weight-saving innovations:
- 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 also gives reduced expansion.
- Titanium aluminide stage 6 and 7 low pressure turbine blades.
Fuel burn reduction technologies include:
- Fan bypass ratio of 19:2, 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.[2]
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.
- Lower internal engine temperatures 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.
[edit] Applications
[edit] Specifications
General characteristics
- Type: Turbofan
- Length:
- Diameter:
- Dry weight:
Components
- Compressor:
Performance
- Maximum Power output:
- Power-to-weight ratio:
[edit] References
[edit] External links
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