On the ambiguity of premixed flame thickness definition of highly pre-heated mixtures and its implication on turbulent combustion regimes

Abstract

Freely propagating, one-dimensional, laminar, premixed flames of ethylene–air are analysed at standard temperature and pressure (STP) and at elevated temperature and pressure conditions to reveal the differences in flame structure. For high-temperature and low-pressure conditions, there is a significant contribution to the total heat release in the post-flame region leading to an ambiguity in the definition of the characteristic flame structure thickness. The potential implications on the identification of the appropriate turbulent flame regime in Borghi or Re-Da regime diagrams are highlighted. The contributions of individual reactions to the total heat release across the entire flame structure are analysed to understand the impact of turbulence–chemistry interactions.