With the Airbus A320neo expected to enter flight testing this fall, equipped with the Pratt & Whitney P1000G Geared Turbo Fan and the Bombardier CSeries, also with the GTF, already in testing, PW is already engaged in research to improve fuel efficiency by up to 10% by the middle of the next decade.
During the PW Media Days last month, we sat down with Robert Saia, vice president of Next Generation Product Family, to discuss how this will be accomplished.
Saia describes what he calls a 10-year technology road map PW follows in its development process.
“The intent of that roadmap was to go look at unique technologies that were very, very immature,” he told us. “When you get to level 6, it says the technology is mature. It’s mature where the technology has been tested in an engine environment at the temperatures, pressures or speeds that it would be used in a product.”
Technology level research (or TLR) of one or two “are kind of an idea that has some analytical substantiation” Saia says. “Three is an experiment, still analytical, that validates the technology has purpose. Technology four is where you have tested that at a part level. For instance, if I have a new compressor and an aerodynamic design, I’ve tested it in a wind tunnel. Technology five is where you put that unique part into a sub-system. TRL six is where I have taken that sub-system and have run it in an engine at the conditions it would intended to be used in the future product.’
Saia says that a 10-12 year technology roadmap was laid out for the GTF with two objectives.
“The first is to get to what we call our advanced GTF, which is to get from a gear ratio of three to a gear ratio of 4-4 ½. The objective is to get from a bypass ratio of about 12, which is where we are today, to a bypass ratio in the 15 to 18 level.”
This would step up the value of the gear and shrink the core size, Saia says. The other element of the road map is to look at aerodynamic features, compressor air foils and turbine air foils, materials—such as new powder materials—and new turbine materials, the latter two items affecting operating temperatures.
But the research doesn’t end with the fan, core and systems. The engine nacelle is also a critical component. Boeing’s nacelle on the 787 is an important element of achieving this airplane’s fuel savings goals, and the design was applied to the 747-8. Initially, Boeing showed concepts of the 777X with a similarly designed nacelle, but has since moved to a design that it consistent with today’s 777, according to Aviation Week.
With the acquisition of Goodrich, Saia says PW is looking at advanced nacelle concepts; Goodrich is one of the industry’s leading nacelle designers and producers. Weight and drag is a driver in the net fuel efficiency result.
“Our objective is to get about a net 1% fuel efficiency improvement per year,” Saia says. “We’re talking by mid-[next] decade getting about 10%. We recognize that’s pretty aggressive, but the thought…is that if we can reach 10%, that puts the advance geared system on an installed base the equivalent to an open rotor. Although the open rotor can be a more efficient engine, when you look at things like noise, containment or air foil protection in the event of one of these fan blades were released, we thought that a 10% improvement would put us at the equivalency of an installed open rotor without the debit for noise.”
Saia says that as PW looks at this significant fuel improvement goal, the company wants to bring about half into a technology insertion package that the early GTFs could benefit from.
Testing the engines, of course, are also important steps in achieving fuel efficiency and reliability. Although there were headlines last month—some unnecessary hand-wringing in nature—over the failure of a GTF engine on the Bombardier CSeries, BBD said the fault lay within the low pressure turbine, not the GTF, and The Wall Street Journal suggested that oil starvation may have been the cause.
We were also told by BBD that the engine, on Flight Test Vehicle 1, was one of the prototypes installed on the first three test airplanes. The first production engines are installed on FTV 4, which completed only three or four flights when the incident occurred.
The CSeries incident occurred on the ground during a test run-up. Full analysis is still pending.