After years of development and testing on the ground, the brand new GE9X engine is finally in the "status" of frozen design, that is, the final characteristics of the engine have already been defined.
In this way, GE Aviation is ready to forward this engine to the certification process, which involves another series of tests, and the use of other engines, different from some that have so far contributed to the development of the project.
An “upgraded” engine (Unit 008) will be incorporated into the test Boeing 747-400 later this month for flight testing at a GE facility in Victorville, California. This engine already incorporates the updates and troubleshooting arising from the development phase.
Boeing will probably receive two GE9X engines by the end of November, for the installation and inspection of the operation of accessories on the first 777-9X, which will make its first flight in the first half of 2019.
GE's intention is to allow about 9 months of intense work for engine certification before the final part of the aircraft's certification, avoiding delays to the 777-9X program. During this period, until July of next year, the Boeing 777-9X itself will fly with the engine without certification, but there are no problems, it is an experimental plane.
“We are close to 50% of the certification process. We will be very busy for the next 6 to 9 months.”, said GE9X program general manager Ted Ingling.
“We were a little limited in what we could accomplish on the first setup, but we took an early look at the performance numbers to allow the software engineers to start working on it. It really helped with our schedule.”, said Jon Ohman, GE test pilot, talking about a problem that occurred between the difference in engine behavior on the ground and during flight, at 40000 feet, this needed a lot of work on the software to try to alleviate something that would only come in this new hardware upgrade.
After completing 105 hours of flight time, the next testing effort should take place from November to possibly March, “we are anticipating a really high operational pace”, says Ohman. “It's going to be a busy (testing) campaign conducted at a relatively high pace. The first campaign was a snapshot of sorts, and this will cover more critical milestones for certification. We will be exploring more at low altitude and other edges of the envelope in this test campaign.”
Unit 004 was dismantled and updated with new parts, according to the changes presented In this link, it will be used for ground tests, which serve to the changes during the certification process, both at the software level and in the structural part. Units 003 and 002 are carrying out tests on the ground, mainly those related to structural integrity in situations of object collisions and fatigue.
Unit 005 is undergoing vibration tests, to the operation of the engine in an adverse condition, where the weight imbalance can seriously damage its internal components. Engines 006 and 007 are being overhauled, and later they will undergo collision and resistance tests.
Another two spare engines are being assembled.
Designed for long distances at high altitudes, the GE9X has a compressor pressure ratio of 27:1, the highest of any commercial engine developed to date, and an overall pressure ratio of over 60:1. The core intensifies the use of ceramic matrix composites (CMC) in addition to the same material used in the CFM Leap 1 to coat the turbine, this engine also incorporates an advanced design in the high pressure (HP) turbine blades and a pre-scroll last generation annular in the combustor, among other new technologies.
In this way, GE was able to create an engine that was about 12% more economical, compared to the GE90 that equips the 777-300ER. It is worth mentioning that the 777-9X is more efficient in the aerodynamic part, and even with the greater weight, the engine only has 100 thousand lbs of thrust.
The core is vital to the overall performance improvement of the GE9X compared to the GE90, the High Pressure compressor provides an improvement in fuel burn compared to previous designs of up to 2%.
“We've added another stage to get that extra boost, and now we're getting the operability right and making it free. That's where the magic is, plus the efficiency”, says Ingling.
Even so, most of the economy is derived from the greater efficiency between the cold and hot part of the engine, that is, the higher by- ratio (cold air VS hot air) caused by the larger front fan, is able to improve the propulsion, without affecting consumption so much. In addition, the new front fan blades are more efficient, which is why we only find 16 of them on this engine, while a GE90 needs 22. Here, the influence of the GEnx engine is notorious.
Via - Aviation Week
