9/17/2024 Jenny Applequist
Written by Jenny Applequist
The upgrades will support R&D on environmentally friendly propulsion systems for the future.
For almost a decade, the Center for Power Optimization for Electro-Thermal Systems (POETS) has pursued innovations in electric powertrains for transportation systems ranging from cars and trains to ships and small aircraft. Now, a $2.7 million award from the Federal Aviation Administration’s Fueling Aviation’s Sustainable Transition (FAST) program will upgrade the POETS testbed to enable testing of larger aircraft power and propulsion systems than it can currently handle.
But the point isn’t only to study larger conventional aircraft, but to advance high-powered electrified airplane technologies that could one day mitigate the environmental impacts of air transportation.
Kiruba Haran is the principal investigator for the new grant as well as the director of POETS, a Grainger Chair, and a professor of electrical & computer engineering.
“We are working on a big problem,” he said. “That’s to decarbonize aviation. And electrification is one way to get there.”
Unfortunately, such electrification won’t be possible in the immediate future, particularly because safety is paramount in the context of aviation.
As Haran put it, “We don’t have the luxury of saying ‘let’s learn by trying it out on the aircraft’!” Instead, everything must be thoroughly tested on the ground; only then can new technologies be integrated into actual aircraft.
The POETS testbed’s expansion—which is the only infrastructure project that received a FAST low-emission aviation technologies grant—will increase its capabilities in three respects.
First, a 1-megawatt motor drive test stand will be constructed to enable full-scale demonstrations of aircraft propulsion systems. That’s a fivefold expansion of the current testbed’s 200-kilowatt capacity.
Today’s testbed can operate “primarily in the power range of terrestrial vehicles and smaller aircraft,” Haran explained. “This megawatt will allow us to test systems that are capable of [powering] small regional jets.”
Second, a furnace and a cryogenic system will be added to study how components respond to extreme heat and cold. The furnace will offer temperatures of up to 600°C so that high-temperature-resistant components and thermal insulation can be studied in realistic operating conditions. The cryogenic system will allow researchers to study possible innovations for future aerospace systems.
“One of the most exciting, but further out, technologies is superconducting machines,” Haran said. “Superconducting machines operate at very low temperatures. So that’s the need for this cryogenic capability.” Hydrogen fuel cells may be part of the future solutions, and it might be necessary to carry the hydrogen in liquid form; but liquefied hydrogen boils at about −253°C. “How do you safely carry liquid hydrogen? How do you transfer it around? And potentially use that hydrogen to cool the electric machines so they can be superconducting? So the [cryogenic] test capability would help.”
The third upgrade will be a suite of tools for assessing reliability of insulation, ability of components and subsystems to endure vibrations and shocks, and tolerance of electromagnetic interference (EMI).
Haran noted that the general public already has some inkling of concerns with EMI. “You know how we turn off our cell phones and all that when we are about to take off? It’s not exactly the same thing but, you know, there is all this concern about what’s happening to communication and data integrity in the aircraft,” he said. “We’re going to take the engines that used to be mechanical, jet engines, and we are going to make them electric. There is a huge amount of electric power and a lot of dynamic operation... So there is this concern about... the interference that comes from the electromagnetics.”
Haran said “that’s another big piece” of what the next-generation testbed will be used to study, through the features that can characterize EMI performance.
POETS is a multi-university National Science Foundation Engineering Research Center (ERC) that is approaching the end of its NSF support. However, ERCs are not intended to end with their NSF funding, but should “graduate” to long-term existence under other support. The FAA award will be one important piece of the future of POETS.
“We have a good group of industry partners that are members of the center that will sustain our activities going forward,” Haran said. “And enhancing the testbed infrastructure will help strengthen the center’s capabilities as we move into that future. And also I’d add... not just to sustain, but it gives us the capability to kind of launch something bigger, perhaps, right?”
Rolls-Royce, RTX, Boeing and the Air Force Research Lab will partner with POETS on the testbed effort. Sherry Yu, a U. of I. alumna who returned to campus to serve as the testbed manager for POETS, will lead the implementation of the testbed upgrades.