A team of researchers from the U.S. Army Research Laboratory and the University of Illinois at Urbana-Champaign made an historic first with their experiment in a gas turbine combustor using X-rays.
The researchers use powerful X-rays to see inside a gas turbine combustor during ignition. Image credit: David McNally.
The experiment was conducted at the Advanced Photon Source, Argonne National Laboratory in Illinois.
“This is the brightest hard X-ray source in the Western Hemisphere,” said team leader Dr. Tonghun Lee, from the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign.
“Our experiment mimicked what happens inside a typical helicopter gas turbine engine,” he added.
Inside a gas turbine engine, a combustor is fed high pressure air that is heated by constant pressure.
After heating, the air passes from the combustor through the nozzle guide vanes to the turbine, producing thrust.
Combustors play a crucial role in determining many of an engine’s operating characteristics, such as power density, fuel efficiency and levels of emissions.
“We had a combustion going on, which is done for the first time ever at the Advanced Photon Source and we are imaging the spray breakup at the very tip of the injector using an X-ray source,” Dr. Lee said.
“Typically that region where the liquid breaks up is very dense and it’s difficult to image anything inside there.”
By using the Advanced Photon Source, the team was able to penetrate and understand how the ligaments, or strands of burning fuel, breaks up into small droplets.
“We are trying to understand exactly what occurs inside the gas turbine combustor to understand how it responds to different operating conditions,” Dr. Lee said.
The data gathered during the experiment will become the initial conditions for numerical simulations that will further understanding of gas turbine combustors.
“We’re trying to get an understanding of the physics, which to this day we have been speculating, we can really visualize using this X-ray source,” the scientist said.
“We want to understand what we’re doing right now, understanding the fuel impact.”
In the longer term, the data from the experiment will allow researchers to design more optimized combustor systems for the future.
“Breakthroughs in small engine technology for future unmanned aerial vehicles will enable longer duration, larger payloads and silent operation,” said Dr. Jaret Riddick, director of the Vehicle Technology Directorate of the U.S. Army Research Laboratory.
