Haran works with NASA to bring superconductors to the sky
Rubber shrieks against tarmac as a Boeing 747 ramps up its speed. The seats inside rumble as its wings slice through the air, forcing wind under twin blades. A slight tug on a joystick later, the aircrafts' wheels gently leave the ground and retract into the frame, and hundreds of tons of metal begin gliding up into the clouds.
This procedure, which is usually over in a matter of minutes, requires the aircraft to burn through an average of 5,000 gallons of jet fuel. The airplanes of the future, as per NASA's vision, need to transition to hybrid fuel blends and eventually electricity if planes are to remain viable in a future where fossil fuels are scarce and populations pay more attention to their emissions. This is where Associate Professor Kiruba Sivasubramaniam Haran comes in.
Haran has won an $800,000 preliminary research grant from NASA to explore using superconducting machines to make aircraft engines powerful enough to run on electric power, under the Leading Edge Aeronautics Research (LEARN) project. This is his second research grant from NASA, and his research on these machines is directly related to other work he’s doing with the agency to build lighter, more efficient hybrid and electric aircraft. His new grant lasts 12 months, and if Haran’s team is successful, they will propose a second phase, which could result in more NASA funding.
“I’m thrilled to be working on another NASA project, especially one that parallels the work we’re already doing together,” Haran said.
In Haran’s previous grant, he proposed a number of different ways of making aircraft simultaneously more powerful and more energy-efficient, including cutting aircraft weight, integrating new discoveries in engine development to make them more energy-efficient, and making the aircraft more aerodynamic by distributing the motors differently.
Haran recently came up with another way he could drastically increase engines’ power density: superconductivity. Superconducting materials are much better at carrying current than conventional materials like copper, and allow Haran to push his machines much harder with far less energy.
One caveat is that the magnetic fields these machines generate would be powerful enough interfere with other electromagnetics on board, like the plane’s navigation systems. An incredibly powerful superconducting turbine would be useless if the plane’s pilot loses control the moment the engines turn on.
However, Haran has found a new way to integrate superconductors while shielding the rest of the aircraft from the strong magnetic fields they create, called “active shielding.” His technique: to surround the superconducting machine with a set of strong electromagnetic coils.
While the superconductor is running, current runs through those surrounding coils, generating a magnetic field. With a precise electromagnetic design, the coils can create their own equivalent magnetic field that bucks against the one coming from the superconductor, keeping the force inside the motor instead of it reaching out and interfering with the airplane’s other electromagnetic systems.
Haran’s design was inspired by the way that MRIs work when imaging patients. They use similar techniques of creating counter-magnetic fields in order to keep magnetic fields inside the machine instead of reaching outwards. Haran was impressed by how elegantly the same concept could transfer to integrating powerful superconductors into airplanes.
“Since this not a constraint anymore, we can ramp the fields up to the limit of superconductors are capable of,” Haran said. “It’s very exciting to be able to integrate this discovery into aircraft, because we can now work with magnetic fields an order of magnitude higher than the machines of today. This can result in aircraft engines exponentially more powerful and efficient.”
Haran is doing this work with Mechanical Engineering professor and co-principal investigator Andrew Alleyne, a number of faculty collaborators that will work with Haran through the Grainger Center for Electric Machinery and Electromechanics, partners at Ohio State University, the Air Force, electromagnetics software company Magsoft, and a new, highly promising cadre of graduate students. One of them, David Loder, is already improving the design by using a sophisticated genetic algorithm based optimization scheme. Tim Deppen, who works as a postdoctoral associate with Alleyne, is also assisting.
“The new crop of students that came in last year, they’ve really ramped up their progress quickly,” Haran said. “They impressed all of our key stakeholders a lot, and perhaps NASA took that as a sign that our program holds special promise when they awarded us an additional research grant. Seeing what our new students are capable of, I’m ecstatic to bring them on board. I think NASA looks at Illinois as a very capable team.”
Collaborating with Haran at the Air Force Research Laboratory is research team leader and physicist Timothy Haugan. Haugan worked with Haran on previous projects as far back as 2009, and said it was great to have a chance to work on a team with him again, as well as to be working on the forefront of electric aircraft technology.
“I worked closely with him in the later years about 2009 forward as a program manager for MEPS, and knew him generally before that,” Haugan said. “For this current project, Kiruba has years of experience developing megawatt-power machines. It's very exciting to be part of the teams working on technologies needed for a new revolution in aircraft propulsion.”