According to the official website of GE on October 12, 2021, the GEnx engine completed over 3000 cycles of vacuum testing in simulated harsh environments using specialized vacuum equipment, achieving excellent durability test results. The dust durability test will ensure that GE's fastest selling high thrust engine in history continues to provide high-quality service to customers in the next decade. In an instant, the GEnx engine has been in service for ten years. What is the unique feature of this engine tailored for the "Dream" aircraft?

1、 Basic information

The General Electric Next generation engine is an advanced twin rotor axial-flow large bypass turbofan engine designed by GE Aviation for the Boeing 787 and 747-8. GEnx is positioned to replace the CF6 engine in GE's product line. In order to meet the requirements of "green aviation" in the 21st century, GEnx inherits and develops the design concept of GE's mature engines, especially the GE90 engine, draws on the experience and lessons learned from the development and use of GE90, and adopts the latest advanced technology, which not only achieves high performance of GEnx, but also greatly shortens the development cycle.

Main model: GEnx-1B (one of the Boeing 787 engines, competing with the Rolls Royce Trent 1000)

GEnx-2B (the only engine choice for Boeing 747-8)

Thrust: 240-330 kN (between CF-6 and GE90)

Culvert ratio: around 9

Total pressure ratio: around 55

Performance indicators: Compared with CF6 engine, fuel consumption and carbon dioxide emissions are reduced by 15%, exhaust temperature margin is increased by 35%, number of components is reduced by 30%, wing life is extended by 30%, and noise is reducedThe sound is reduced by 30%.

2、 Development history review

In the spring of 2003, the development of GEnx began;

In 2004, GE launched the GEnx-1B to participate in the bidding for the Boeing 787 engine;

In 2005, GE secured an order for 525 GEnx engines for the Boeing 787 and 747-8;

On March 19, 2006, GEnx began ground testing;

On February 22, 2007, GEnx completed its maiden flight test and installed an engine on the Boeing 747-100;

In 2011, the GEnx engine was officially put into use to power the 747-8 aircraft of Luxembourg Cargo Company;

In 2012, the first Boeing 787 powered by GEnx was delivered to Japan Airlines;

In 2019, a Boeing 787-9 aircraft equipped with GEnx engines by Qantas completed a record breaking commercial flight, covering 16415 kilometers (10200 miles) of land and sea from New York to Sydney in 19 hours and 16 minutes, spanning 15 time zones;

In November 2019, the 2000th GEnx was delivered, completing a total of 4.5 million flight cycles and 26 million hours across 60 operators;

In 2020, the cumulative sales volume of GEnx exceeded 2500 units, making it the fastest growing high thrust engine in GE's history and widely recognized by customers;

In 2021, durability tests were completed, verifying the improvement effects of multiple components and achieving a new round of technological breakthroughs. During its ten-year service life, the GEnx carried over 370 million passengers and transported over 46 million tons of cargo.

3、 Key Technology Analysis

The GEnx engine uses lightweight and durable materials and advanced design processes to reduce weight, improve performance, and lower maintenance costs, making it the best choice for many long-distance flights and setting a sales record for high thrust commercial turbofan engines. Numerous key technologies jointly support the design goals of low fuel consumption, low pollution, and low noise. The summary is as follows:

(1) Provide megawatt level electrical energy for Boeing 787 aircraft

On traditional large passenger aircraft, most systems are driven by compressed air. For example, the high-pressure air used in the cabin air conditioning system is provided by the exhaust from the engine's high-pressure compressor. At the same time, the high-pressure hydraulic pump of the hydraulic system is driven by the transmission shaft on the engine accessory transmission casing. The Boeing 787 adopts an airless architecture, using an AC electric motor to drive the air compressor and hydraulic pump, making it a "quasi electric" aircraft. Therefore, a high-power AC generator driven by the engine is needed to provide sufficient electrical energy.

Traditional aircraft have one generator driven by each engine and one generator driven by the APU, while the Boeing 787 has a total of six generators. Two GEnx engines drive four generators, providing the main electrical energy. Each generator has a power generation of 250 kilowatts, and the APU drives two secondary generators, each with a power generation of 225 kilowatts. If six generators are started simultaneously, a total of 1.45 megawatts of electricity can be provided, which is four times the power generation of the Boeing 777 and equivalent to the power generation capacity of solar panels the size of 10 football fields.

(2) Two major designs to reduce fuel consumption

One is the huge external duct and composite material fan. The bypass ratio of GEnx is 9:1, and the fan blade diameter reaches 2.8 meters. The weight is reduced by using carbon fiber composite material fans and casings. The previous generation of fans was made of titanium alloy, which has high specific strength, but carbon fiber has higher specific strength and stronger rigidity. Carbon fiber composite fans have a larger diameter and thinner thickness. Compared to titanium alloy fans, the new material reduces the number of fan blades from 22 to 18, ultimately achieving a 15% weight reduction and a higher upper limit of fan speed.

The second is the extremely high boost ratio of the compressor. GEnx has the highest pressure ratio compressor among current commercial engines, increasing the pressure ratio can maximize the use of energy released by the fuel, and the more energy is converted by the turbine and nozzle. The pressure ratio of GEnx can reach up to 58:1, and as the pressure ratio increases, the number of compressor stages decreases by 4 compared to CF6. GEnx has improved the performance of its blades through the use of three-dimensional aerodynamic technology and integrated manufacturing of the entire blade disc, further enhancing aerodynamic efficiency.

(3) Reducing nitrogen oxide emissions through a dual ring premixed cyclone (TAPS) combustion chamber

The core technology of TAPS combustion chamber is the introduction of innovative premixed concept while maintaining the advantages of zone combustion. In order to achieve the optimal temperature distribution factor in the combustion chamber and reduce NOx emissions, GE has applied micro stratification technology in the fuel nozzle to achieve a smooth transition of combustion. Therefore, the air and fuel are well pre mixed before the combustion chamber. There are three air cyclones for the fuel nozzle in the combustion chamber, one for the swirl intake of the main mixer and the other two for the swirl intake of the secondary mixer. This is the key to achieving micro stratification technology for the fuel nozzle. The center of the TAPS nozzle is the ignition flame, and the main nozzle is annular, generating two layers of swirling flow. In the pre mixing stage, a large amount of air is required to ensure lean combustion. This nozzle looks simple, but requires countless simulations and iterative designs to gradually approach the target. Without the latest generation of metal 3D printing technology, such a complex structure would be difficult to manufacture. After 26 years of research and development, nitrogen oxide emissions have been reduced by 60%.

TAPS can achieve lean combustion of engines under all operating conditions, with higher combustion efficiency, lower flame temperature, and lower pollution emissions. It is a more advanced and structurally simpler combustion chamber, representing the achievements and development direction of modern aviation turbine engine combustion chamber engineering technology. TAPS has been further developed and utilized in LEAP and GE9X engines, achieving stronger lean combustion and lower nitrogen oxide emissions.

(4) Cleverly designed to reduce noise

The reduction of GEnx engine noise is mainly attributed to its iconic exterior design - serrated nozzles. Due to the need for turbofan engines to rapidly spray air and gas from the inner and outer ducts at a speed much higher than the flow rate of the outside air, the interaction with the outside air can cause severe mixing and generate huge noise, like a waterfall hitting the water surface. The serrated nozzle is used to control the airflow ejected, causing each serrated nozzle to generate small eddies, making the high-temperature and high-speed jet mix more gently with the outside air, greatly reducing the noise generated by the engine.

According to statistics from GE, there are currently over 2700 GEnx engines in service and on order. In just ten years of operation, GEnx's performance can be described as dazzling. In the competition among the three giants of commercial engines in the world, GE still firmly occupies half of the market with its large bypass high-pressure core engine, composite materials, and additive manufacturing technology. From CF6 and CFM56 to GE90 and GEnx, and then to LEAP and GE9X, GE's star products are constantly emerging. As mentioned in the GE Aviation Centennial Review, they will continue to reshape the future of flight.

Source: Global Aviation Information