Investigation of the dynamical response of methane/air counterflow flames to inflow mixture composition and flow field perturbations

This work presents an analysis of the response of laminar, stretched, premixed CH₄-air counterflow flames subject to periodical perturbations of the inflow mixture composition and the flow field in the context of ILDM and REDIM. Investigations of the perturbation propagation show, that the perturbation reaches the flame under certain conditions only; changes of the perturbation due to dissipative processes are investigated. Different methods are applied to gain an in-depth view of the influence of the perturbation on the chemical kinetics, namely correlation analyses of species in state space and timescale and element composition analyses. For the timescale analyses, two methods are applied, the ILDM method and a new concept for timescale analysis within the REDIM method. It is shown, that the perturbation does not change the global behaviour of the chemical kinetics and it is suggested to apply REDIMs for a low-dimensional description of perturbed flames.