Tickling a jet engine

Daniel J. Bodony

When one thinks of supercomputers, jet noise probably isn’t the first thing that comes to mind.

However, reducing jet noise is just one of the things for which they can be used.

Daniel Bodony, the Blue Waters associate professor of Aerospace Engineering at Illinois, uses supercomputing resources from Extreme Science and Engineering Discovery Environment (XSEDE) to calculate the mechanics behind jet noise.

“We use XSEDE resources because there’s no simple way of writing down on pen and paper how much noise a jet engine produces,” Bodony says. “Instead, we use computer programs that solve for the motion of all of the gas behind a jet engine.”

Bodony is currently using XSEDE supercomputing resources for two projects. One is for the US Navy, which is interested in reducing jet noise for workers who are close to tactical fighters on aircraft carriers.

“When you think of the power of a jet engine, you generally think of a really powerful engine that can move and transport several hundred people several hundred miles an hour over several thousand miles,” Bodony notes. “The generated sound is an extremely small part of the power produced by the engine. We're trying to tickle the jet in the right way, just trying to very lightly touch the engine to change the noise significantly.”

The other project is for the National Aeronautics and Space Administration (NASA). NASA has a slightly different problem than the Navy. Instead of reducing jet noise through an exhaust system, they reached out to Bodony about diminishing the noise of fans on their aircraft.

The applications of Bodony’s work for NASA might prove to be an important component of future aircraft designs. Bodony says that jet engines can be redesigned to produce power for electric motors instead of producing thrust.

“Instead of having two very large engines that produce thrust at two or four very specific points on the aircraft, you treat those jet engines not as thrust producing devices but as power producing devices for electric motors,” Bodony says.  “Then, you distribute the electric motors across the airplane. Once you have a large number you can think about designing an airplane differently.”

The Stampede supercomputer at the Texas Advanced Computing Center (TACC) was an important resource for Bodony. Bodony ran calculations that used half a billion grid points to simulate the motion of air as it exhausts from a jet engine.

“To accurately predict jet exhaust noise, it takes approximately 500 million grid points to describe the jet exhaust and each grid point carries five pieces of information. Roughly 1 million timesteps are needed to simulate the exhaust in time, and each timestep requires hundreds of floating point operations for each grid point. An entire simulation requires nearly an exaFLOP of calculation.”

Bodony says this work wouldn’t have been possible without XSEDE and its Extended Collaborative Support Services (ECSS) program, which provided both computational and personnel support.

“XSEDE’s ECSS have helped us over the years by making our programs much more efficient,” Bodony says. “We can use the same amount of resources, but produce much more useful information."

This story was reposted with permission from the Indiana University ScienceNode.