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The opening into this fuel spray injection chamber provides an eye into the interior of diesel engines during fuel injection. |
X-rays reveal the secrets of diesel combustion |
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For the first time ever, a team of scientists at Argonne is using X-ray beams to penetrate diesel fuel injector sprays to improve combustion. They have uncovered a shock wave in gas sprays and other data that may lead to cleaner, more efficient engine injection systems. “This research has been full of excitement since the idea of using ‘X-ray vision’ to study high-pressure fuel sprays was first conceived four years ago,” said Jin Wang, who is the driving force behind the experiment. The team of researchers from the Experimental Facilities and Energy Systems Divisions uses X-rays from the Advanced Photon Source (APS)—a facility dedicated to producing synchrotron X-ray beams for research—to study the fuel injection system of an engine and how combustion works. Researchers are simulating a high-pressure injection similar to that of a passenger car. The APS’ X-rays probe the fuel spray through a window built into the side of the simulated engine combustion chamber. X-rays passing though are measured by a point detector that maps the absorption image of fuel sprays. “It gives us the ability to track the fuel mass of a spray,” said engineer Steve Ciatti. “It’s unique. The standard is to use optically based techniques like lasers, but with those techniques you can only see the external functions.” The team can define the fuel structure and track where it is at any given time using the APS. In addition to the never-before-seen shock waves, they found air and fuel vapor in the diesel spray core. The unexpected shock waves tell researchers that there is more to learn about the fluid mechanics of fuel spray, Wang explained. Ciatti said their research is critical because cleaner diesel engines are important for reducing air pollution from semi-trucks, trains, and potentially, diesel-hybrid automobiles. And more efficient diesel engines would cut reliance on imported oil and associated costs. The research is still in the early stages of development, but the team plans to continue, increasing the temperature and pressure surrounding the fuel injector to create a more diesel-like atmosphere. The X-ray technique may be used in the future for similar studies of dense plasma and other optically dense structures. The research team won the U. S. Department of Energy 2002 National Laboratory Combustion and Emissions Control R&D Award. The team was also named as a finalist in Discover Magazine’s 2002 Innovation Awards, and their research was highlighted in Science. For more information, please contact Evelyn Brown. See Argonne’s research facilities are open to qualified researchers Next: New section - Energy & Environment |