(10/31/2016) Fire is one of the most destructive forces on earth. It is one of the elements which man has feared, tried to control, as well as tried to harness as a tool; for good and evil. And it truly has uses for both. In nature, for instance, fire clears away old growth and buildup, leading to a clean and fresh new ecosystem filled with an abundance of nutrients and new life.
However, there are times when this renewal process becomes far more harmful than helpful. It can spread to more areas than “need” it, and even into areas populated by us humans. With this in mind, scientists have been long studying fires, and more so forest fires, to help control them as well as combat them. And among the various types of fires seen in forest fires is the fire vortex, commonly called a “firenado”. And because of the nature of these types of fires, they often burn hotter than other forms of fire.
Much like with standard tornadoes, if scientists can determine out how they start, how they move, and other factors, they can better predict, mitigate, and even combat the fire. But use it as a tool? We already do selective burning, and even use fire as back-burns to prevent the spread of fires. But there would simply not be any practical need to create “firenados” to assist us with wildfires.
Enter three research scientists from The University of Maryland (Huahua Xiao, Michael J. Gollner and Elaine S. Oran) and Jim Beam.
The scientists saw a video of a burning pond in Kentucky, at a Jim Beam facility. And the amazing thing about this fire was that the whiskey that had spilled into the pond wasn’t simply burning off, but it had spontaneously formed firenados. And these forms of fire tend to burn fuel hotter and more efficiently, and cause less soot than other kinds of fires. And with that, the light-bulb went on. Could this type of fire be used to help clean up oil spills?
So the three scientists began to experiment. Using not whiskey, but n-heptane (an ingredient added to fuels to test engine performance). They poured it on top of water placed in a pan about 16 inches in diameter. And when lit, they channeled air to produce the desired vortex fire. It worked exactly as predicted and formed a wonderful firenado about two feet tall, with the classic yellow and orange flame.
Then something unexpected happened. The small firenado shrunk. It became not only smaller, but its color changed from orange and yellow to blue; and it’s shape also changed. Dr. Xiao calls this new flame a “blue whirl”. And then when the fuel was all consumed, the small blue twirling flame died out. As their experiments continued, they placed a small tube under the water and fed the fire with more fuel, to continue their examination of the process.
The significance of this new blue swirling flame is twofold; first it is that it had never been seen before in vortex fires, and the second is that blue flames burn more cleanly than yellow and orange flames. What causes a flame to turn yellow and orange is soot created by the burning process entering the flame itself. And in blue flames there is significantly less of this “dirty” byproduct. So for them it was a double win in their experiments. And they were able to produce similar results using crude oil as their fuel.
Now the true challenges come. They are able to reproduce a firenado in lab conditions, but they still don’t understand how the smaller blue whirling flame is created; though they are able to reproduce it consistently in the lab. They are analyzing fuel evaporation, air and fuel mixtures, and other factors to determine exactly what is happening. And once they have figured it out, they will move on to larger scale experiments and hopefully develop a controllable tool to assist in oil spill cleanups.