Engineers have discovered a brand-new, bright-blue fire tornado that behaves unlike any flame ever created.
When a fire burns yellow, it’s unclean. The warm colors are signs of an incomplete combustion reaction coughing up soot, smoke, and other emissions. When a flame glows blue, it’s a sign of a more complete, near-perfect burn with far fewer emissions. But that kind of burn is rare.
A new kind of whirling flame that’s small, blue, and transparent — like a ghost top — offers a new way to achieve such a clean burn.
Researchers had never created anything quite like this blue-and-violet fire tornado before. But now that they know how to light one, it presents some exciting opportunities.
In a paper describing the phenomenon, University of Maryland engineers suggest that a version of the blue whirl might be a cleaner way to burn off oil spills in the ocean.
Here’s what we know about how the spinning fire works:
Engineers squirt a liquid fuel, n-heptane, onto a pool of water in a round glass tank. Then they light it.
The fire sucks oxygen from the air, and slits in the side of the tank make the wind rush in at an angle that gets the fire spinning. Now they have a regular fire tornado.
To tame the yellow fire tornado, the engineers injected a slow, steady stream of fuel into it from below. Centered on that trickle of extra heptane, the flame shrunk and assumed its blue top shape.
You can see it happen here:
Once the injected fuel was cut off, the flame died out.
The researchers do not yet fully understand the fluid dynamics of the new blue whirl, but they write that it’s easy enough to create and maintain for extended periods. In the paper, they say they kept one blue whirl going for eight minutes before shutting off the fuel source.
It’s just a lab experiment so far, but the prospect of a cleaner way to burn off oil on water’s surface is pretty exciting. And it doesn’t hurt that it’s so pretty, too.