More on global quenching of premixed Ch ₄/diluent/air flames by intense near-isotropic turbulence

In 2002, Yang and Shy reported a global quenching (GQ) criterion of premixed CH4 flames by turbulence characterized by a Karlovitz number (Ka) estimated at reactant temperature and an equivalence ratio ().This article re-analyzes such criteria based on a modified Ka estimated at mean temperature of reactants and products together with newly obtained GQ data at even higher Ka. This modified criterion is compared with a recently found ignition transition, which are then used to evaluate the boundary of thin and broken RZ regimes (Ka=100) proposed by Peters (2000). It is found that flame GQ occurs beyond the broken RZ regime, where critical Ka100 at 0.6 <1.3 forms a parabolic curve with the maximum Ka c365 occurring possibly near =1, except for very rich flames where Ka c=28 at =1.45. A simple model is proposed to explain these results.