Humans may have thought they mastered the flame back in the Stone Age, but hundreds of thousands of years later and fire is still a cause of fascination and confusion.
Scientists from the University of Maryland have described a previously unobserved form of fire in a study published in Proceedings of the National Academy of Sciences. Dubbed the “blue whirl”, the flame glows nearly completely blue and rapidly spins on top of a water’s surface.
“Blue whirls evolve from traditional yellow fire whirls,” Elaine Oran, Glenn L. Martin Institute professor of engineering and co-author of the paper, explained in a statement. “The yellow color is due to radiating soot particles, which form when there is not enough oxygen to burn the fuel completely. Blue in the whirl indicates there is enough oxygen for complete combustion, which means less or no soot, and is therefore a cleaner burn.”
But this blue whirl doesn’t just make for a pretty picture. For one, it could be used to further the study of vortices and vortex breakdown in fluid mechanics. The researchers also believe it could have some real-life applications outside the lab, as its properties provide a stable, clean, efficient, and easy-to-produce flame that could be used to clear up oil spills.
“Fire whirls are more efficient than other forms of combustion because they produce drastically increased heating to the surface of fuels, allowing them to burn faster and more completely,” explained Michael Gollner, assistant professor of fire protection engineering and co-author of the paper, in the statement. “In our experiments over water, we’ve seen how the circulation fire whirls generate also helps to pull in fuels. If we can achieve a state akin to the blue whirl at larger scale, we can further reduce airborne emissions for a much cleaner means of spill cleanup.”
The researchers are not totally sure of the mechanism that forms the blue whirl. Regardless, they’re still excited about its demonstration of high efficiency, low-emission combustion.