Famille CF34

There are four ARJ21-700s in the flight test programme and all are powered by the GE CF34-10A engine.
GE general manager for the CF34 turbofan programme, Chuck Nugent, says the engine-maker has also delivered spare engines to Comac and produced three -10A engines for GE's own ground test programme that was carried out in the US and totalled 750hr of testing.
"We have validated all the changes to the -10A via ground testing and the additional testing will be done as part of the ARJ21 flight test programme," he says.
"The engine certification is nearing completion and we expect to receive certification in the next month or two," he says, referring to US FAR 33 certification.
This will be followed by Chinese CAR 25 certification, he adds.
The first production engine is due to be delivered to Comac in the fourth quarter, says Nugent.
GE's -10A engine has been performing well in the flight tests because the CF34 is already a proven engine, says Nugent.
"The CF34-10A is a derivative of the CF34-10E engine used on the Embraer 190/195 and essentially the turbofan engine is nearly identical although we made some changes to support the ARJ21's fuselage-mounted application and we made some minor improvements."
GE's -10E engine is mounted under the Embraer regional jet's wing, whereas the -10A engines are mounted towards the rear of the ARJ21 fuselage.
"We designed a completely new nacelle, driven by the fuselage mounted configuration, and there were some slight aerodynamic improvements achieved with the nacelle."
"We also redesigned some structural components for the fuselage mounting, so we looked to reduce weight."
He also says: "We've been implementing fuel reduction improvements to the -10E and -10A."
Nugent adds, that GE is in the process of introducing a new fan blade for the -10E and -10A that promises to deliver "a slight improvement" in fuel burn.

aeroduO5 a écrit:
Pour moi la véritable menace pour les E-Jets c'est le MRJ. Les autres avions ne feront pas beaucoup mieux.

GE Aircraft Engines has not forsaken the market for smaller turbofans. At least one of two other programs under development–the TechX–could enter service as early as 2015 on a large-cabin business jet, depending on the timing of a launch customer signing, while a program called NG34–a technology development effort involving the immensely successful CF34–would ready GE’s bid to power the next generation of regional jets.


Expected to cover the next generation large cabin business jets in the 10,000- to 20,000-pound-thrust range, the TechX engine draws on the latest technologies from existing engine programs, such as the low-emission TAPS (twin annular premixed swirl) combustor from the GEnx and the latest Fadec technology from the F136 engine for the JSF. Some of the features of the TechX engine include:


• GE’s new eCore, which features a high-pressure-ratio compressor in the 20:1 class range, advanced materials, unique cooling technologies, next generation TAPS combustor for efficient, cleaner fuel combustion and lowest NOx, third-generation 3-D aerodynamic design airfoils and a two-stage high-pressure turbine.


• Advanced clearance control in the turbine in which the Fadec controls the air to maximize efficiencies.


• A so-called Slimline nacelle to minimize drag and improve component accessibility, with the Fadec in the nacelle for a cooler environment and easier access for maintenance.


Claimed benefits of the TechX include 20-percent lower fuel consumption, 40-percent lower emissions, a stall-free design, no throttle restrictions and a similar core to those used in the proven CFM56 and CF34 turbofans.


Meanwhile, GE’s aspirations for a successor to today’s CF34 appear just as lofty. Again, NG34 technology centers on a low-emission core, called eCore, expected to offer 15- to 20-percent better specific fuel consumption than today’s CF34 engines. CFM will use the same core on the Leap-X, while GE borrows the technology for the TechX as well. The first eCore completed Phase 1 testing earlier this year and the company has begun Phase 2 testing. The tests center on the turbine and combustor.

Unlike in the GEnx, the fan would consist of solid titanium rather than composite. GE has determined that the extra thickness needed for a small composite fan capable of passing bird ingestion tests would increase the weight to the point of negating any benefit of using nonmetallic material. Like the GEnx and TechX, however, the new CF34 would use TAPS combustor technology, allowing pressure ratios to exceed 20:1. The TAPS combustor also results in 50- to 60-percent lower NOx emissions compared with CAEP 6 limits, and 10- to 15- EPNdb margin to Stage 4 limits.


As designers raise the pressure ratio and temperature in the core, they also need to improve the efficiency of the turbine. Turbine blades would use what GE calls the latest design advances to improve aerodynamics. Rig testing on the new design is to happen within the next two years.


As in the case of the current engines, GE would most likely supply the entire propulsion system for the next-generation CF34 engines. A nacelle integration team now works with the NG34 development teams as GE considers the use of composites as well methods to better integrate the engine and nacelle.


The new CF34 engine would occupy a thrust class between 14,000 and 18,000 pounds–a range similar to that of today’s CF34-8 and CF34-10 engines.