Observation of the Distributed Reaction Zone in Turbulent Premixed Flames

An observation method for the distributed reaction zone in turbulent premixed flames was proposed. A mixing layer between a combustible mixture and a hot burned gas, which existed in a uniform shear layer, was studied to observe the interaction between the turbulence and reaction. A typical "wrinkled laminar flame" appeared when the equivalence ratio of the mixture was 0.65, and for an equivalence ratio much lower than the flammability limit, a structure which looked like a "distributed reaction zone" was observed. In the latter, and intermediate "reactedness" and a thick reaction zone were observed by the detection of fluctuating temperature, ion current and chemiluminescent emission of the zone.