The structure of a diffusion flame with a three-step chain mechanism, consisting of two high-activation-energy thermoneutral branching reactions and a zero-activation-energy termination reaction, has been studied using activation energy asymptotics via the model problems of counterflow and droplet flames. The analysis identifies three types of flames, depending on whether the rate of the termination reaction is fast, moderate, or slow as compared to the rates of the branching reactions. For the fast recombination regime a unique extinction criterion has been derived which contains a chain extinction limit and a global extinction limit; the latter case is identified as Linan's extinction criterion. For the moderate and slow recombination regimes distinct extinction states do not exist.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy(all)