(photograph) Thermal pulse combustor at University of Tennessee, College of Engineering, Combustion Research Laboratory, part of the Chaos Research Group's current interests. Tubes supply fuel (propane), air, and water (to cool transducers). Exhaust is toward the left.
Pulse combustion occurs when fuel and oxydizer react chemically (combust) in the presence of a standing acoustic wave. Although fuel and oxydizer generally are admitted to the combustor continuously, combustion is not continuous but rather pulses in phase with the acoustic pressure front. The natural frequency of oscillation is strongly determined by the length of the exhaust-gas tailpipe, but fuel and oxydizer input rates also influence combustion behavior.
The thermal pulse combustor is the simplest form of pulse combustors. Gaseous fuel and oxydizer (usually air) are fed at constant rates into the combustion chamber, and a thermal mass (hot spot) at the center of the chamber helps initiate combustion at the beginning of each combustion pulse. Exhaust gases flow out of the tailpipe. The combustion chamber and tailpipe combination serve as an acoustic resonator.
Pulse combustors have many practical applications, the most common of which is in industrial water heaters. Pulse combustion can be problematic in that cycle-to-cycle combustion is irregular (either stochastic or chaotic). The primary goal of the CRG's research in thermal pulse combustion is to apply chaos-control techniques to improve combustor performance. Active control could have profound effects in reducing undesirable pollutant emissions and in fuel efficiency. Chaos control has already been demonstrated on a pulse-combustor numerical model.
We have compiled a "Bibliography of chaos and pulse combustion" to assist in further research.
If you are interested in an ancient (1802) account of research regarding acoustics and combustion, then read "Memoir on tubes rendered harmonious by hydrogen gas" by G. Delarive.
Primary contacts for this research area are: C.S. Daw, K. Nguyen, and K.D. Edwards.
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Copyright © 1996-2002 C.E.A. Finney. Unless specified, use in any medium of any contents at this site is permitted, provided the source URL be acknowledged and the copyright notice be included. This page's URL is http://www-chaos.engr.utk.edu/res/pulsecombustion.html.
Photograph Copyright © 1997 K.D. Edwards.
Updated: 2001-12-27 ceaf