GE Aerospace has won a Phase 2 contract under NASA’s Hybrid Thermally Efficient Core (HyTEC) program which will contribute to next-generation single aisle engine technology in development for GE/Safran joint venture CFM International’s RISE (Revolutionary Innovation for Sustainable Engines) initiative.
The latest phase, which officially gets underway in February 2024, will build on small core technology work undertaken in the initial part of the HyTEC program. To date, this has focused on the development and testing of advanced high-pressure (HP) compressors, HP turbine blade aerodynamics and cooling, environmental barrier coatings for vanes and blades, and advanced ceramic matrix composites (CMCs) for combustor liners.
GE is also working on a power extraction demonstration under HyTEC, with Phase 2 building on the company’s ongoing efforts to develop more electric engines, including the previously awarded NASA Turbofan Engine Power Extraction (PEX) demonstration contract awarded under the first phase of HyTEC.
“We have many demonstrators and many tests running, and they all build on each other and start combining,” says Arjan Hegeman, GE Aerospace’s general manager of advanced technology. “So, this is just the latest chapter in the progress that we’re making towards the future of flight with the RISE program.”
Speaking to Aviation Week, Hegeman says, “the most visible piece of the RISE program is clearly the open fan, which is a key piece of getting to better propulsive efficiency. This gives you a large bypass without the drag of an ever-increasing fan cowl size. But clearly, that fan needs to be driven by the core, and that’s where thermal efficiency comes in. The smaller you make that core the further you increase that bypass—the more air goes through the fan and the less air you put through the core, the better your efficiency is. So, the compact core is a key ingredient to us getting to the 20%-plus efficiency improvement over today’s engines.”
Phase 1—which overlaps with the start of the new phase—is focused on maturing discrete technologies to a particular technology readiness level (TRL), Hegeman says. Phase 2 “is more about integrating all of them into a compact core which will be demonstrated in the latter half of this decade,” he adds.
Part of the HyTEC technology suite that will feed into RISE includes next generation turbine blades and nozzles that were evaluated earlier in 2023 on an F110 combat engine in Evendale, Ohio. The tests, first disclosed in June, “represented a step change in how we do the cooling of those blades. That test has been completed and was extremely successful—so that’s an example,” Hegeman says.
“It’s not only just the next generation type aerodynamic shapes that we’re developing, but with that comes our cooling technologies, and it’s a similar—but smaller scale story—for HyTEC. You have got to make sure it integrates at the component level and that it all works. In this case, we had an F110 engine that we’re testing this blade technology in and that feeds into this compact core demonstrator that we’re working our way towards in Phase 2,” says Hegeman, who adds that the compact core is “significantly smaller” than the high-pressure system on an F110.
“The blade that we tested in the F110 now gets designed for this compact core—same for the combustor and same for the compressor. Then, of course, there’s the hybrid electric element that starts feeding into this HyTEC Phase 2,” he says. Although the high-pressure core will be considered technology readiness level (TRL) 5-6 when it proceeds to integrated testing, the low-pressure spool will necessarily be simulated—meaning that the full integrated engine will still be far from mature at that stage.
Although GE Aerospace is already engaged with NASA on the megawatt-class Electrified Powertrain Flight Demonstration [EPFD] program, the maturation of hybrid electric technologies for future narrowbody applications is under the PEX effort with HyTEC. “That starts looking at extracting those power levels in a narrowbody thrust class type application,” Hegeman says. The work will answer questions such as “how exactly does it work, how do you control it, how do you control the electric piece of the hybrid system, and how do you control the gas turbine piece of hybrid electric?”
“That starts leaning already on the learnings from EPFD. Then in Phase 2 you take all that and you have a true new center line designed compact core with the hybrid electric (element) implemented the way we are envisioning it will be in future narrowbody applications,” he adds.
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