Scientists have now mapped the structure of the unusual rotating fire
The researchers’ blue-blue flame was annoying when it first appeared in a lab experiment. Scientists have now defined the structure of this “blue vortex”.
Four different types of fire make up the blue vortex, the researchers reported to Science Advances on Aug. “It’s amazing,” said Elaine Oran, an engineer at Texas A&M University at College Station.
The blue vortex reported in 2016 occurred when scientists dispersed liquid fuel floating above water in an enclosure designed to allow air to flow into a vortex (SN: 18 / 08/16). A tornado fire erupted before settling on an inch high blue flame. This hue indicates that it burns without soot, suggesting that such flames can be useful for cleaning up oil spills or making electricity more environmentally friendly.
Most fires fall into two general classes: primary and diffuse. As the fire diffuses, the fuel and oxidant – usually oxygen – are initially separated, limiting the rate at which the fire can burn. The two explode together in the premixed fire. There are three types of premixed flames. They may have an excess or a lack of fuel compared to the oxidizer, known as rich or lean premixed flames. The Stoichiometric Flame is the Goldilocks variety with the right amount of fuel for complete combustion.
By comparing computer simulations with experimental experiments, Oran and his colleagues determined the structure of the blue vortex. Its conical base is a rich, premixed fire crowned by a diffuse fire. A small flame of fire will appear on the sides like a light breath. Where these three flames meet, a stoichiometric flame forms, forming a light blue ring.
If the structure of the flame is known, researchers can learn how to measure or create a larger-scale blue vortex without going through the dangerous phase of the Firenado.
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