Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

To Extinguish a Hot Flame, DARPA Studied Cold Plasma

13.07.2012
DARPA performers demonstrate techniques to manipulate and extinguish small flames locally using electric and acoustic suppression; results could benefit combustion research

Fire in enclosed military environments such as ship holds, aircraft cockpits and ground vehicles is a major cause of material destruction and jeopardizes the lives of warfighters. For example, a shipboard fire on the aircraft carrier USS George Washington in May 2008 burned for 12 hours and caused an estimated $70 million in damage.

For nearly 50 years, despite the severity of the threat from fire, no new methods for extinguishing or manipulating fire were developed. In 2008, DARPA launched the Instant Fire Suppression (IFS) program to develop a fundamental understanding of fire with the aim of transforming approaches to firefighting.

Traditional fire-suppression technologies focus largely on disrupting the chemical reactions involved in combustion. However, from a physics perspective, flames are cold plasmas. DARPA theorized that by using physics techniques rather than combustion chemistry, it might be possible to manipulate and extinguish flames. To achieve this, new research was required to understand and quantify the interaction of electromagnetic and acoustic waves with the plasma in a flame.

The IFS program was executed in two phases. In Phase I, performers studied the fundamental science behind flame suppression and control, exploring a range of approaches before down-selecting to electromagnetics and acoustics. In Phase II, performers determined the mechanisms behind electric and acoustic suppression and evaluated the scalability of these approaches for defense applications.

One of the technologies explored was a novel flame-suppression system that used a handheld electrode to suppress small methane gas and liquid fuel fires. In the video below, performers sweep the electrode over the ignited burner array and progressively extinguish the 10-cm2 gas flame. Since the electrode is sheathed in ceramic glass, no current is established between the electrode and its surroundings. A visualization of gas flows during the suppression would show that the oscillating field induces a rapid series of jets that displace the combustion zone from the fuel source, leading to extinguishment of the fire. Put simply, the electric field creates an ionic wind that blows out the flame. This same approach was not able to suppress a small heptane pool flame.

Performers also evaluated the use of acoustic fields to suppress flames. In the video below, a flame is extinguished by an acoustic field generated by speakers on either side of the pool of fuel. Two dynamics are at play in this approach. First, the acoustic field increases the air velocity. As the velocity goes up, the flame boundary layer, where combustion occurs, thins, making it easier to disrupt the flame. Second, by disturbing the pool surface, the acoustic field leads to higher fuel vaporization, which widens the flame, but also drops the overall flame temperature. Combustion is disrupted as the same amount of heat is spread over a larger area. Essentially, in this demonstration the performers used speakers to blast sound at specific frequencies that extinguish the flame.

IFS Phase II was completed in December 2011. IFS performers succeeded in demonstrating the ability to suppress, extinguish and manipulate small flames locally using electric and acoustic suppression techniques. However, it was not clear from the research how to effectively scale these approaches to the levels required for defense applications.

Remarking on the overall impact of the IFS program, Matthew Goodman, DARPA program manager, said, “We have shown that the physics of combustion still has surprises in store for us. Perhaps these results will spur new ideas and applications in combustion research.”
For example, the data collected by the IFS program could potentially be applied to the inverse challenge of fire extinguishment, namely increasing the efficiency of combustion. Such technology could be especially beneficial to defense technologies that employ small engines.

Associated images and videos posted on www.darpa.mil and http://www.youtube.com/user/DARPAtv may be reused according to the terms of the DARPA Usage Agreement, available here: http://go.usa.gov/nYr.

DARPA Public Affairs | EurekAlert!
Further information:
http://www.darpa.mil
http://www.darpa.mil/NewsEvents/Releases/2012/07/12.aspx

More articles from Physics and Astronomy:

nachricht Physicists edge closer to controlling chemical reactions
11.12.2018 | Moscow Institute of Physics and Technology

nachricht UA-led OSIRIS-REx discovers water on asteroid, confirms Bennu as excellent mission target
11.12.2018 | University of Arizona

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

Im Focus: Substitute for rare earth metal oxides

New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals

Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.

Im Focus: A bit of a stretch... material that thickens as it's pulled

Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.

Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...

Im Focus: The force of the vacuum

Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.

The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

Expert Panel on the Future of HPC in Engineering

03.12.2018 | Event News

 
Latest News

Some brain tumors may respond to immunotherapy, new study suggests

11.12.2018 | Studies and Analyses

Researchers image atomic structure of important immune regulator

11.12.2018 | Health and Medicine

Physicists edge closer to controlling chemical reactions

11.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>