INTRINSIC LOW-DIMENSIONAL MANIFOLDS OF STRAINED AND UNSTRAINED FLAMES

The intrinsic low-dimensional manifolds of strained and unstrained pre mixed CH4-air flames are analysed. We show that in typical flame appli cations only a small domain of the state space is accessed. This is fo und by simple one-dimensional flame computations using different strai n rates. Secondly, in the different flame regions a different number o f time scales is rate limiting. This means that in different regions t here exist different numbers of relaxed modes corresponding to equilib ration processes (species in quasi-steady states, reactions in partial equilibrium). It is shown that even in critical zones of the flame, s uch as the pre-heating zone, a considerable number of time scales can be decoupled from the equation system, guaranteeing an accurate descri ption of the flame front by automatically simplified kinetics.