Characterization of the local flame structure and the flame surface density for freely propagating premixed flames at various lewis numbers

Abstract

The local flame structure and the flame surface density for freely propagating premixed turbulent flames are measured by laser sheet tomography and image processing techniques. Different fuel/air mixtures (methane, propane, and hydrogen) have been successively spark-ignited at atmospheric pressure in order to evaluate the influence of thermodiffusive effects characterized by the Lewis number, at quasi-constant ratio u′S L 0 . From the instantaneous flame front positions and the mono-dimensional mean progress variable distribution, spatial statistics including the turbulent flame brush, the mean orientation factors, and the components of the normal vector to the flame front have been characterized and compared with numerical and experimental results available in the literature. The temporal evolution of the flame surface density was also determined by several approaches and analyzed in terms of maximum flame surface density evolution and location of maximum flame surface density. It clearly appears that th...