On the route to extinction in non-adiabatic flames from competitive exothermic reactions

Abstract

We consider non-adiabatic combustion waves arising from two-step competitive exothermic reaction schemes. A numerical method is employed to study the behaviour of this system and we show that the inclusion of heat loss can lead to a period-doubling route to the termination of the propagating flame front. The nature of oscillations becomes more complex with increasing loss of heat until the system can no longer sustain a propagating front. In other words, beyond some critical value of heat loss, extinction of the combustion reaction would occur. For the non-adiabatic case, particularly close to the extinction threshold, large excursions in temperature and wave speed above those observed for the adiabatic case can occur. Such behaviour close to extinction may have implications for safety or industrial processes.