Sound Waves: Untapped Fire Extinguishers?

Popular version of paper 3aEA10
Presented Wednesday morning, October 19, 2005
ASA/NOISE-CON 2005 Meeting, Minneapolis, MN

Since its inception, the space program has wrestled with firefighting techniques. From the Apollo 1 disaster to the more recent destruction of the space shuttle Columbia, control of heat and combustion have been a primary concern. Despite the significant role it plays in the success of mission, we know very little about fire, or combustion, and how to manipulate it. Very few methods exist for combating fires in zero gravity. Of the methods that do exist there are three widely accepted extinguishers: the carbon dioxide, the water-foam, and the Halon 1301. All pose specific threats to either the crew or equipment and are extremely ineffective. The Prometheus Project, an undergraduate student research group, proposes to explore the feasibility of using sound waves to manipulate and extinguish a flame.

Fire here on Earth is an extremely complicated process. Though combustion itself is a chemical reaction, gravity plays a major role in shaping it and strongly influences the amount of energy given off by a fire. In order to simplify the process and study the chemical process by itself, the team decided to conduct its experiments in a zero gravity environment. Unfortunately, gravity is present here on Earth so the team is left with a dilemma. Luckily, NASA offers a program known as the Reduced Gravity Student Flight Opportunities Program (RGSFOP) which allows students to use NASAs zero gravity simulating aircraft to experience and conduct experiments in microgravity. The aircraft, also known as the Weightless Wonder, flies a parabolic pattern, climbing to heights of 35,000feet and then free-falling to 25,000 allowing its occupants to experience up to 30 seconds of weightlessness.

Tests in one-g (here on Earth) have proven very successful. An initial test was conducted with a shockwave cannon as a sound source. The candle was completely isolated in a bottle and the cannon was fired at it. Since the candle was enclosed in a bottle, this means that it could not possibly have been air movement blowing the candle out but the sound waves interrupting the combustion process.

The next step was to design an apparatus to fly aboard the Weightless Wonder. This is no small feat as NASAs safety guidelines are very stringent. Simple tasks, such as lighting a candle, become exponentially more difficult when they must be performed within a sealed chamber by an automated process. The final design contains a large interior cage with a candle surrounded on three sides by subwoofers. The speakers can be programmed to play whole tones (single frequencies) or wav files. Temperature, pressure, sound intensity and microphone data are collected along with regular and infrared video of each test. Experiments in one-g revealed that frequencies from 15 Hz to 55 Hz are most effective for extinguishing the candle.

The support for this project has been quite astounding. What began as four students locked in a room banging out a proposal has manifested itself into a project which now weighs in at 34,000 dollars, thousands of hours of labor and nearly 300lbs. Our team has grown from the founding four to five undergraduates, one graduate and two professors. The single most amazing thing about this project is that it is completely student run. It was an idea proposed, pursued and brought to fruition entirely by undergraduates. In fact, one of the students was only 17 when she began working on the project. Now 18, she has had research published in two scientific journals. This is more than some graduate students can say for their research! The professors served as guides and advisors, working side-by-side with the students to reach feasible solutions for difficult challenges.

The current team members are Dmitriy Plaks, Nesha Hyatt, Zade Coley, Ross Cutts and Elizabeth Nelson. Dmitriy is a senior at Georgia Tech majoring in Aerospace Engineering and Physics. He is one of the original four and, as team captain, is responsible for the project as a whole. He specializes in computer and software design while overseeing every other aspect of the project. Nesha Hyatt is an Electrical Engineering major at Auburn University. Though a later addition to the team, she proved invaluable as a pressure and ignition system specialist and is responsible for the structural analysis. Zade Coley is a Physics major at the University of West Georgia. He is responsible for structural design and creation of the sound files. Elizabeth was 17 when she joined Dmitriy in beginning the project. She is now, at the age of 18, a junior Aerospace Engineer at the Florida Institute of Technology. She is responsible for the electrical and computer systems on the apparatus. Ross Cutts is the newest member. A junior Civil and Environmental Engineering major at Georgia Tech, he was recruited as a software specialist. These students are aided by Dr. James Espinosa, a physics professor in his second year at the University of West Georgia. With such an excellent team, the students are confident of great success.

The applications of this technology here on Earth are just as astounding as in space. Instead of sprinkler systems, buildings could be equipped with fire extinguishing systems designed to bombard specific areas with sound. Millions could be saved in damaged documents, furniture, carpets etc. As there is no previous documentation of any experiment in this field, the possibilities are endless. The students hope to continue their project by not only exploring ways to optimize their fire-fighting system but also to explain the mechanism behind their results. For more information, such as contact information, member bios, videos, etc, you may visit the project website at http://www.westga.edu/~rgsfop.