Understanding Extinction of Nonpremixed Flames Subject to Brief Periods of High Dissipation Rates

摘要

The existence of a critical dissipation rate, above which a nonpremixed flame is extinguished, has been known for decades. Recent advances in modeling have allowed the simulation of turbulent nonpremixed flames that include local extinction as a consequence of the stochastic variation in mixing rates. In this paper we present the critical dissipation impulse magnitude that will lead to extinction even if the mean dissipation rate is well below the criteria for a steady flame. This critical impulse magnitude depends on the time-integrated excess dissipation rate, stoichiometric factors and the form of the S-curve describing the steady-state flame. This criteria is evaluated in a diverse set of flames including n-heptane, diluted n-heptane and CO/H{sub}2/N{sub}2 mixtures.