Flame wrinkle destruction processes in harmonically forced, laminar premixed flames

Abstract

This paper describes numerical and theoretical analyses of the nonlinear dynamics of harmonically forced, stretch-sensitive premixed flames. A key objective of this work is to analyze the relative contributions of kinematic restoration and flame stretch upon the rate at which flame wrinkles, excited by harmonic forcing, are smoothed out. Kinematic restoration is an intrinsically nonlinear process with a two spatial-zone structure, whose amplitude dependence is fundamentally different near and far from the wrinkle excitation source. Flame stretch processes appear even in the small perturbation limit, and smooth out flame wrinkles in thermodiffusively stable mixtures. Which process dominates is a function of the perturbation amplitude, frequency, stretch sensitivity of the mixture, and spatial location. This paper presents computed results illustrating the solution characteristics, as well as key dimensionless parameters controlling the solution based upon a third order perturbation analysis.