Shock Wave Interaction with a Flame

Shock wave/fire interactions initiated by high explosives have been historically demonstrated as potentially effective ways to control oil well fires or even forest fires in situations where conventional means cannot be applied. However, the mechanisms by which a fire can be extinguished by a shock wave are not well understood. A series of experiments have been conducted involving a moving shock front and trailing expansion flow, exhausted from the open end of a small shock tube, interacting with a simple small-scale flame – little research into this interaction has been conducted in the public domain. High-speed schlieren video of the transient flowfield was captured as the shock tube exhaust passed through a flame, causing a swift cessation of the combustion process. This visual data was used in to analyse the details of the instabilities which the shock induces in the flame, and the procedure of extinguishment during the flame’s removal from the fuel source by the following jet. The results supplied new insight into the mechanisms of shock/fire interaction and allowed for a greater understanding of the means by which the flame is eventually extinguished. The limitations and suitability of this small-scale testing for studying applicability to large-scale fires are also discussed in the paper.