MechSE welcomes new associate professor Tonghun Lee

One of the newest faces of the MechSE department is that of associate professor Tonghun Lee. Lee was previously an associate professor at Michigan State University in Lansing, Michigan in their Mechanical Engineering Department. His research is in combustion, with a specific focus on laser and optical diagnostics, and with two main applications: propulsion and energy.

Lee's main focus in propulsion is on hypersonic systems. Hypersonic propulsion refers to high speed engines which can propel the aircraft at many times the speed of sound. Most airborne propulsion systems, like those on modern commercial airplanes, rely mainly on gas turbines which operate in a much slower regime.

"Let's say we wanted to go from Champaign to Tokyo in less than five hours," Lee said. "We can't do that with our current gas turbines, because we’d need to go many times the speed of sound. And to do that we’d need to have an engine with combustion at these high velocities. I mainly want to ensure that combustion can occur in a stable way at these extreme velocities inside the aircraft engine."

Maintaining combustion stability is very difficult inside an engine traveling Mach 6 (more than 4,500 miles per hour) when the combustion depends on oxygen intake and proper mixing with the fuel. The oxygen it takes in will be from the surrounding air traveling Mach 6 in the opposite direction, which makes the flow very hard to control. There are also thermal concerns, as the friction created from traveling at those speeds is immense, and therefore creates immense heat both in the airflow and on the surfaces of the vehicle.

Lee also studies the combustion of biofuels, an effort supported by the United States Army, Navy, and Air Force. Petroleum-derived fuels are the most widely-used fuels, although the United States generates very little of the petroleum it uses. A desire to ease the country’s dependence on fuel it cannot produce has sparked interest in biofuels created from organic matter, such as plants. One such candidate is the camelina sativa plant, a plant very high in oil content that grows in uninhabitable regions and cannot be used as a food product.

"There is an effort to diversify alternative fuel blends that can come from bio products," Lee said. "So those are plants, biostock, algae, anything that lives. It's not a solution that’s going to take over petroleum, but it will be a huge portion of our future energy infrastructure. As the defense industry invests money to develop the technology, it will merge into the commercial sector sometime in the future."

Lee received his bachelor's degree in mechanical engineering in 2000 from Yonsei University in Seoul, South Korea. He then moved to the United States, where he completed his master's degree (2002) and Ph.D. (2006) in mechanical engineering at Stanford University in Stanford, California. He says he had two main reasons for his coming to Illinois.

"A lot of it was the prestige of the engineering college here," Lee said. "And there are a lot of colleagues in my field that I can interact with. Those are the main reasons I came to Illinois."