Future Firefighters Might Snuff Flames with Electricity
Firefighters wage war on flames with water, chemical retardants and sand. Studies presented this week on the interaction between combustion and electrical fields could soon arm them with electricity as well. The new effort, funded by the Defense Advanced Research Projects Agency, could lead to firefighting tools that clear paths in flames by manipulating electric fields.
In an experiment recorded by the Whitesides Research Group at Harvard University, a single flame stands at attention over a gas burner until, suddenly, it wavers and disappears. No one has blown it out, and nothing around it has moved. The only thing that changes in the experiment is an electric field focused at the base of the flame.
"It's like a person walking very fast in a room full of people," said Ludovico Cademartiri, a chemist in the Whitesides lab. "This flow is what destabilizes the flame, what puts it out."
The flow changes the shape of the flame, ripping it from its fuel source until it starves.
Take the simple case of a candle. As the flame eats away at the wick, it generates a cloud of gas and soot particles, some of which carry a charge. An electric field applies force to the charged particles, spurring them into action. When Cademartiri turns on the amplifier in his own experiment, soot particles in the flame fly out, knocking into neutral gas molecules and carrying them along in a flow.
Blowing on a candle can have the same effect, but only if it’s done with enough power. When a child blows out his birthday candles, the flow of air molecules comes from outside the flames. If there’s not enough force, the imported oxygen can actually feed the combustion, strengthening the flame.
"What's important to realize is this is not like blowing on a flame," Cademartiri told InnovationNewsDaily. “In this case it’s internal."
A device that fought fire with volts rather than water or chemicals could reduce damage to houses. But it would have to be very safe. The Whitesides group was dealing with a flame about 20 inches (50 cm) tall, small fry to a seasoned firefighter.
Nonetheless, their experiments have proven to be no more dangerous than shaking the static electricity out of a sweater in the winter.
"I've been electrocuted many times by that amplifier and I’m still talking to you," Cademartiri said.
This article was provided by InnovationNewsDaily, a sister site of TechNewsDaily.