Passage Times and Flamelet Crossing Frequencies in Premixed Turbulent Combustion

Abstract

An earlier analysis of the characteristic scales associated with the mean reaction.rate in a premixed turbulent flame is extended by revising an important modeling assumption. In the previous work the distribution of passage times of burned and unburned gas packets is represented by an exponential probability density function which is analytically convenient but inapplicable at small passage times. The present analysis employs a gamma two distribution which removes this shortcoming and is in good agreement throughout the range of such times with the limited experimental data currently available. Modified expressions are obtained for the distributions of the time autocorrelation function, the mean reaction rate and the normalized time scale through a planar flame. Further experiments are required to test these predictions.