Blue whirl. Photo: Sriram Bharath Hariharan/University of Maryland
A fire phenomenon known as the blue whirl can emerge from fire tornadoes. This week scientists reported new details of the structure of the mysterious clean-burning flame.
Why it matters: Researchers hope to one day harness the blue whirl as a source of energy and to clean up fuel spills. To do that, they need to understand the flame's form — and how it might be controlled.
- Fire whirls generate soot (though not as much as typical fires) — small particles of carbon produced when fuel isn't completely burned and that give a flame its yellow color.
- In a lab, the whirls can transition to become blue whirls, in which the fuel is completely combusted and no soot is produced.
What they did: Joseph Chung, Xiao Zhang and their colleagues at the University of Maryland created a computer simulation of the blue whirl and compared it with video of the flame forming in the lab.
- They found the whirl is made up of "a diffusion flame and premixed rich and lean flames — all of which meet in a fourth structure, a triple flame that appears as a whirling blue ring," they write in Science Advances.
- Blue whirls haven't been seen in nature. Why and under what conditions they may occur in nature are still open questions, says Chung.
What's next: "This is a first step to applying the blue whirl to a more practical application," says Zhang. There are more questions, she adds, for example: whether a larger blue whirl can be created so it can burn more effectively (it is currently just a few inches in size) and whether it can burn faster.