Yuhe Ren, Niklas Manz, and I recently published an article Guided flame: reaction-diffusion of fire pulses in narrow channels in the journal Open Transport. Machinist Tim Siegenthaler helped make the channels. This work had been gestating for a long time, but has recently became a hot topic. Fortunately, Yuhe was able to acquire all our data in the last year, spanning his Junior I.S., Wooster summer REU (thanks to the Koontz Endowed Fund), and Senior I.S.
We studied fire propagation in annular channels whose rectangular cross-sections are a few millimeters wide and high and whose circumferences are hundreds of millimeters long. If a channel is partially filled with a volatile flammable hydrocarbon fluid, locally igniting the vapor above the fluid can start a fire pulse that rapidly propagates around the annulus at hundreds of millimeters per second leaving behind an unexcitable region of depleted vapor, a refractory tail. Further evaporation of the volatile fluid restores the vapor and the corresponding excitable condition, allowing the returning pulse to propagate, provided the channel’s circumference is sufficiently long.
Experimentally, we explored this quasi-one-dimensional reaction-diffusion system, discovering simple trends connecting refractory tail length and pulse propagation speed to channel length, height, and width. Computationally, we introduced phenomenological computer simulations that simply reproduce the guided flame and elucidate the underlying physics.
Yuhe’s overhead video of a blue hydrocarbon flame propagating at almost one meter per second counterclockwise in a narrow channel in a fume hood. (You may need to click or tap to see the motion.)