The General Electric GEnx ("General Electric Next-generation") is an advanced dual rotor,
axial flow
An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from othe ...
,
high-bypass turbofan
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...
jet engine
A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...
in production by
GE Aviation
GE Aviation, a subsidiary of General Electric, is headquartered in Evendale, Ohio, outside Cincinnati. GE Aviation is among the top aircraft engine suppliers, and offers engines for the majority of commercial aircraft. GE Aviation is part of the ...
for the
Boeing 787
The Boeing 787 Dreamliner is an American wide-body jet airliner developed and manufactured by Boeing Commercial Airplanes.
After dropping its unconventional Sonic Cruiser project, Boeing announced the conventional 7E7 on January 29, 2003, ...
and
747-8
The Boeing 747-8 is a wide-body airliner formerly developed by Boeing Commercial Airplanes, and the largest variant of the 747.
After introducing the 747-400, Boeing considered larger 747 versions as alternatives to the proposed double-deck ...
. The GEnx is intended to succeed the
CF6
The General Electric CF6, US military designations F103 and F138, is a family of high-bypass turbofan engines produced by GE Aviation. Based on the TF39, the first high-power high-bypass jet engine, the CF6 powers a wide variety of civilian a ...
in GE's product line.
Development
![General Electric GEnx on 747-8I prototype](https://upload.wikimedia.org/wikipedia/commons/3/38/General_Electric_GEnx_on_747-8I_prototype.jpg)
The GEnx and the
Rolls-Royce Trent 1000
The Rolls-Royce Trent 1000 is a high-bypass turbofan engine produced by Rolls-Royce plc, one of the two engine options for the Boeing 787 Dreamliner, competing with the General Electric GEnx.
It first ran on 14 February 2006 and first flew on ...
were selected by Boeing following a run-off between the three big engine manufacturers. The GEnx uses some technology from the
GE90
The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aviation for the Boeing 777, with thrust ratings from . It entered service with British Airways in November 1995. It is one of three options for the 777 ...
turbofan, including swept composite fan blades and the 10-stage HPC featured in earlier variants of the engine. The engine carries composite technology into the fan case.
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
Bleed air is compressed air taken from the compressor stage of a gas turbine upstream of its fuel-burning sections. Automatic air supply and cabin pressure controller (ASCPCs) valves bleed air from high or low stage engine compressor sections. Low ...
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 was expected to produce thrust from 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 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.
[General Electric Performs First Run of New GEnx Engine]
" ''Flight International
''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldes ...
''. 21 March 2006. The first flight with one of these engines took place on 22 February 2007, using a
Boeing 747-100
The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022.
After introducing the 707 in October 1958, Pan Am wanted a jet times its size, to ...
, fitted with one GEnx engine in the number 2 (inboard left hand side) position.
By Fall 2019, General Electric was offering the GEnx-2B, developed for the 747-8, for the revised
767-XF variant based on the 767-400ER, but needed enough volume to cover the new product certification.
Operational history
Introduced in late 2011 on a 747-8 freighter,
Cargolux
Cargolux, legally ''Cargolux Airlines International S.A.'', is a Luxembourgian flag carrier cargo airline with its headquarters and hub at Luxembourg Airport. With a global network, it is one of the largest scheduled all-cargo airlines in Europe ...
surpassed one million flight hours in early 2017.
[
On July 28, 2012, the NTSB initiated an investigation of an engine failure that occurred on a Boeing 787 during a pre-delivery taxi test in Charleston, South Carolina.]
on August 31, 2012, a GEnx-1B engine installed on a Boeing 787 that had not yet flown was found to have an indication of a similar crack on the fan midshaft. The fan midshaft was removed from the engine for further inspection and examination. As a result of investigative work the NTSB has determined that the fan midshafts on the GEnx engines fractured or cracked at the forward end of the shaft where the retaining nut is installed.
On September 11, 2012, an AirBridgeCargo
AirBridgeCargo Airlines, LLC (Russian: ООО Авиакомпания «ЭйрБриджКарго»), part of Volga-Dnepr Group, is the largest Russian cargo airline with its head office in Moscow. It operates scheduled cargo services on route ...
747-8F experienced a major engine malfunction that spread a significant amount of metallic debris on the runway when the low-pressure turbine shaft separated and shifted backwards, damaging the low pressure turbine blades and vanes. The NTSB issued urgent safety recommendations to the FAA to require ultrasonic scans for midshaft fractures before use of GEnx engines and require repetitive on-wing inspections of the engine to detect cracks.
During the spring and summer of 2013, GE learned of four 747-8F freighters that suffered icing in their engines at altitudes of and above. The most serious incident involved an AirBridgeCargo
AirBridgeCargo Airlines, LLC (Russian: ООО Авиакомпания «ЭйрБриджКарго»), part of Volga-Dnepr Group, is the largest Russian cargo airline with its head office in Moscow. It operates scheduled cargo services on route ...
freighter; on July 31, while at an altitude of over China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, the flight crew noted two engines surging while a third lost substantial power. The pilots were able to land the plane safely but the engines were found to have sustained damage. Among the possible factors cited was "'unique convective weather systems' such as unusually large thunderstorm
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...
s reaching high altitudes." Boeing is working with GE on software solutions to the problem. Altitude was restricted until GE changed the software to detect the high-altitude ice crystal
Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust.
Formation
The hugely symmetric shapes are due to depositional growth, na ...
s and open bleed air
Bleed air is compressed air taken from the compressor stage of a gas turbine upstream of its fuel-burning sections. Automatic air supply and cabin pressure controller (ASCPCs) valves bleed air from high or low stage engine compressor sections. Low ...
valve doors to eject them before they enter the core.[
]
In March 2014, a GEnx-powered Boeing 787
The Boeing 787 Dreamliner is an American wide-body jet airliner developed and manufactured by Boeing Commercial Airplanes.
After dropping its unconventional Sonic Cruiser project, Boeing announced the conventional 7E7 on January 29, 2003, ...
had its first in-flight shut down in operation when a JAL flight had to divert to Honolulu after an oil pressure alert, bringing its in-flight shut down rate to 1 per ,000 hours.
In January 2016 a Japan Airlines
, also known as JAL (''Jaru'') or , is an international airline and Japan's flag carrier and largest airline as of 2021 and 2022, headquartered in Shinagawa, Tokyo. Its main hubs are Tokyo's Narita International Airport and Haneda Airport, as w ...
787 had an inflight shutdown after flying through icing conditions
In aviation, icing conditions are atmospheric conditions that can lead to the formation of water ice on an aircraft. Ice accretion and accumulation can affect the external surfaces of an aircraft – in which case it is referred to as ''airframe ...
, caused by ice formed on fan blades and ingested: the blades moved forward slightly and rubbed on the abradable
An abradable coating is a coating made of an abradable material – meaning if it rubs against a more abrasive material in motion, the former will be worn whereas the latter will face no wear. Abradable Coatings provide a .1 to .2% performance im ...
seal in the casing.[ In March 2016, the US ]FAA
The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...
ordered emergency fixes on the GEnx-1B PIP2. The airworthiness directive affects 43 Boeing 787 Dreamliners in the US. Abradable material in the casing in front of the fan blades was ground to keep them from rubbing when ingesting ice or debris on 330 GEnx PIP-2.
In early 2018, of 1277 orders for the B787
The Boeing 787 Dreamliner is an American wide-body jet airliner developed and manufactured by Boeing Commercial Airplanes.
After dropping its unconventional Sonic Cruiser project, Boeing announced the conventional 7E7 on January 29, 2003, ...
, 681 selected the GEnx (%), 420 the Rolls-Royce Trent 1000
The Rolls-Royce Trent 1000 is a high-bypass turbofan engine produced by Rolls-Royce plc, one of the two engine options for the Boeing 787 Dreamliner, competing with the General Electric GEnx.
It first ran on 14 February 2006 and first flew on ...
(%) and 176 were undecided (%).
The 2,000th GEnx was delivered by November 2019, 15 years after the engine launch, as it logged 4.5 million flight cycles and 26 million hours among 60 operators.
Design
The GEnx is derived from the GE90
The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aviation for the Boeing 777, with thrust ratings from . It entered service with British Airways in November 1995. It is one of three options for the 777 ...
with a fan diameter of for the 787 and for the 747-8.
To reduce weight, it features 18 composite fan blades, a composite fan case and titanium aluminide
Titanium aluminide (chemical formula TiAl), commonly gamma titanium, is an intermetallic chemical compound. It is lightweight and resistant to oxidation and heat, but has low ductility. The density of γ-TiAl is about 4.0 g/cm3. It finds use in s ...
stage 6 and 7 low-pressure turbine blades.
Fuel efficiency is improved by 15% compared to the CF6
The General Electric CF6, US military designations F103 and F138, is a family of high-bypass turbofan engines produced by GE Aviation. Based on the TF39, the first high-power high-bypass jet engine, the CF6 powers a wide variety of civilian a ...
, the bypass ratio
The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for ev ...
reaches up to 9.0:1 and the overall pressure ratio
In aeronautical engineering, overall pressure ratio, or overall compression ratio, is the ratio of the stagnation pressure as measured at the front and rear of the compressor of a gas turbine engine. The terms ''compression ratio'' and ''pressure ...
up to 58.1:1.
It has a 10 stage high-pressure compressor and is quieter, helped by larger, more efficient fan blades.
It stays on wing 20% longer, uses 30% fewer parts to lower maintenance costs and has a contra-rotating
Contra-rotating, also referred to as coaxial contra-rotating, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Examples include some aircraft propellers, res ...
architecture.
The Lean combustor
A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, combustion chamber or flame holder. In a gas turbine engine, the ''combustor'' or combustion chamber is fed ...
reduces NOx gases with required pressure loss and backflow margin.
Fan blades have steel alloy leading edges and the composite fan case reduces thermal expansion.
To reduce fuel burn, the 23:1 pressure ratio high-pressure compressor is based on the GE90-94B, shrouded guide vanes reduce secondary flows and counter-rotating spools for the reaction turbine
A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...
s reduce load on guide vanes.
To reduce maintenance cost and increase engine life, spools with lower parts count are achieved by using blisk
A blisk (portmanteau of bladed disk) is a turbomachine component comprising both rotor disk and blades. It serves as a critical component of the engine compressor to allow a sufficient quantity of compressed air to enter the engine for combustion ...
s in some stages, low blade counts in other stages and by using fewer stages; internal engine temperatures are reduced due to more efficient cooling techniques and debris extraction within the low-pressure compressor protects the high-pressure compressor.
Applications
* Boeing 747-8
The Boeing 747-8 is a wide-body airliner formerly developed by Boeing Commercial Airplanes, and the largest variant of the 747.
After introducing the 747-400, Boeing considered larger 747 versions as alternatives to the proposed double-deck ...
* Boeing 787 Dreamliner
The Boeing 787 Dreamliner is an American wide-body jet airliner developed and manufactured by Boeing Commercial Airplanes.
After dropping its unconventional Sonic Cruiser project, Boeing announced the conventional 7E7 on January 29, 2003, ...
Variants
Specifications
See also
References
External links
*
*
*
{{GE aeroengines
High-bypass turbofan engines
GEnx
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 succeed the CF6 in GE's pro ...
2000s turbofan engines