General Electric is emphasizing the maturity of the advanced technology to be introduced in the GE9X engine for Boeing’s 777X, designed to provide a 10% lower fuel burn than the GE90 powering today’s 777-300ER.
“We will run the high-pressure compressor five years before certification,” says Bill Fitzgerald, GE Aviation vice president and general manager of the commercial engines operation.
The first version of the high-pressure compressor (HPC) is complete and will begin tests in July and two more iterations are planned before design of the 102,000-lb.-thrust GE90X is frozen in 2015.
With a 27:1 pressure ratio, 20% higher than that in the GENx (in turn 20% higher than in the GE90), the HPC is one of the key changes being introduced in the GE9X, which will exclusively power the 777X.
Others are a “fourth-generation” composite fan with wider, thinner (and fewer) blades, and lightweight, uncooled ceramic matrix composites (CMC) for high-pressure turbine (HPT) nozzles, shrouds and blades.
“We have a rigorous technology maturation program on all the parts that change,” says Bill Millhaem, GE90 general manager. “The first 4-5 years are about demonstrating technology..and producibility.”
The 132-in.-diameter fan will use a new lighter, higher-strength carbon-fiber material system, enabling a thinner blade with wider chord and more sweep. Blade count will reduce to 16 from 22 in the GE90.
A composite front fan-case, used in the GENx, will save more than 700 lb. per aircraft over the aluminum case in the GE90, Millhaem says.
The HPC alone will provide 2% fuel-burn reduction, and will feature new powder-metallurgy disk alloys to cope with 80-100-deg. higher temperatures at the back end of the compressor, he says. The HPC will have 11 stages, one more than in the GE90 and GENx.