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New 3-D visualizations that reveal how flames respond to electric fields could help improve combustion efficiency and reduce pollution.
The ability to precisely control flames could lead to greater energy efficiency and fewer harmful emissions from transport and industry. Flames contain charged ions and electrons, which can be manipulated using electricity. KAUST researchers have now produced the first detailed 3-D visualizations of ionic winds flowing from a flame in response to both direct (DC) and alternating (AC) electric fields.
Minsuk - Cha - Coworkers - Model - Ions
Minsuk Cha and coworkers previously developed a theoretical model explaining how ions in a flame respond to electric fields. For their latest work, the researchers ejected a mixture of methane and air through a jet flame nozzle positioned between two electrodes. They illuminated the flame using an argon-ion laser and detected the scattered light in order to trace the motion of individual particles through the flame—a technique called particle image velocimetry or PIV. To improve this visualization, they had to add to the flame reflective seeding particles made from titanium oxide and oil.
"The particle seeding to the ambient flame was quite difficult," says Cha. "We used a smoke generator, but we had to control the timing of the smoke generation very carefully so that we didn't disturb the main flow. It was a time-consuming step requiring a lot of patience."
The researchers acquired...
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