Flow-Geometry and Reynolds-Number Effects on Flame-Turbulence Interactions

Abstract

Three-dimensional direct numerical simulation (DNS) with a detailed kinetic mechanism has been conducted for statistically-planar turbulent flame and turbulent V-flame of hydrogen–air mixture to clarify the effects of mean flow velocity on principal strain rates at flame front and on flame geometry. Reynolds numbers based on Taylor micro scale and turbulent intensity are selected to 60.8 and 97.1, and mean flow velocities for V-flame are 10 and 20 times laminar burning velocity. From results of DNS, eigenvalues and eigenvectors of strain tensor are evaluated to investigate characteristics of strain field near flame and flame normal alignments with the principal axes of strain in detail. It has been revealed that Reynolds number affects both magnitude of strain rates and alignment between flame normal and principal axis of strain, and that the magnitude of mean flow velocity affects flame normal alignments in turbulent V-flame.