Anyone who looks to the stars also dreams of going to space. Turning this dream into reality depends on countless technological advances. One of these is new rocket and aircraft engines, which are becoming easier and cheaper to design and test, thanks in part to scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory.
Better rockets and jet engines will move the dream from our heads closer to reality. More importantly, they will also make air transport cleaner and more efficient while strengthening our national security.
Aerospace and defense companies spend billions over many years to design and test new rockets and gas turbine engines. Fortunately, scientists can slash that effort dramatically when they build a virtuous cycle of experiments and computer simulations. A team of Argonne scientists is combining one-of-a-kind X-ray experiments with novel computer simulations to help engineers at aerospace and defense companies save time and money.
X-rays can open doors
The process starts at Argonne’s Advanced Photon Source (APS), which produces ultra-bright X-rays; they are over a million times brighter than those in a dentist’s office. Using the 7-BM X-ray beamline at the APS, engineers Brandon Sforzo, Alan Kastengren and Chris Powell peer through the steel of an engine’s fuel injector using this ultimate 3D microscope, which sets Argonne’s capabilities apart from others.
“Visualizing through steel with this detail is not possible with any other diagnostic technique,” said Prithwish Kundu, an aerospace engineer at Argonne who develops predictive computer models derived from experiments at the APS, a DOE Office of Science User Facility.
Sforzo agrees. “If you don’t have the brightness of the light we have here, you can’t see what’s going on inside these devices,” he said. “No one else is researching fluid dynamics at the relevant conditions with an accelerator-based light source (the APS’s high-brightness X-ray beams) like we are.”
Back in 2019, the team investigated the fluid dynamics within a gas turbine engine and found behavior that surprised Sforzo and his colleagues. “We could see the liquid spray ending up in unexpected places.”
These types of revelations, described in a new paper, help scientists understand the fundamental physics that, ultimately, affect engine performance, thrust, and emissions. They also give scientists like Kundu, who feed this information into the lab’s supercomputers, building blocks — known as boundary conditions — that enable high-fidelity simulations. They open many doors of inquiry.
A new era of design takes off
Boundary conditions are detailed parameters that act as guardrails; with the right boundary conditions, scientists can build models that predict a host of engine behavior — involving pressure, temperatures, mass, speed and so on — that may be unmeasurable during experiments.
“With the right predictive models, we can reduce testing and development costs by a large margin,” said Kundu.
The quest to cut time and cost has gained momentum. While engineering thrives on high-fidelity 3D models, those models often run for months on supercomputers — a scarce resource for most businesses.
To solve this challenge, Kundu, along with Opeoluwa Owoyele and Pinaki Pal, are now exploring a type of artificial intelligence known as deep neural networks, which help computers find patterns within large, complex data sets. They have already developed neural-network algorithms that significantly reduce the time it takes to optimize models; the equations also help the scientists understand the chaotic inner workings of combustion engines.
“There are so many parameters in an engine — the human mind can’t analyze a 10-dimensional space,” Kundu said.
Using Argonne’s Blues and Bebop high-performance computers, Kundu and Sibendu Som, manager of the laboratory’s Multi-Physics Computation group, recently created a high-fidelity model that measures how two different jet fuels behave in the combustor section of a gas turbine engine.
Their discovery? The computational models were able to predict trends in “lean blowout” — a condition in which a gas turbine engine’s flame sputters in response to less fuel — as shown in a 2018 study.
In another study, Pal, in collaboration with the Air Force Research Laboratory, developed high-fidelity simulations for Rotational Detonation Engines (RDEs). These tools will help engineers accelerate the design of RDEs, which have the potential to enable future supersonic and hypersonic flights.
Warp speed ahead
Kundu and Som’s team are now working with NASA Langley to simulate supersonic combustion and add some of the lab’s models into the space agency’s computational fluid dynamics code, known as VULCAN.
Over at the APS, Sforzo, Kastengren and Powell seek to observe how fuel behaves immediately after it leaves the nozzle. “We hope to move toward more relevant engine conditions — higher pressures, higher temperatures, more relevant liquids,” said Sforzo.
Meanwhile, Kundu awaits those experimental results. “If we can characterize the diameter and the velocities of fuel droplets even closer to the nozzle, the predictive accuracy of our models will increase significantly,” he said.
DOE’s Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office funds the fuel spray research program relevant to gasoline and diesel direct injection.
The Office of Energy Efficiency and Renewable Energy supports early-stage research and development of energy efficiency and renewable energy technologies to strengthen U.S. economic growth, energy security, and environmental quality.
About the Advanced Photon Source
The Advanced Photon Source (APS) is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS.
This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.