Investigation of the hierarchical structure of kinetic models in ignition problems

In this paper a novel method for global analysis of chemical kinetic models is discussed and applied to auto ignition of high hydrocarbons. It is mainly based on the concept of decomposition of motions and follows major steps of the ILDM method. However, a very important difference of the suggested method is its ability of an explicit and global representation of the system decomposition as a standard singular perturbed system (SPS). The fact that the ILDM provides local information about the decomposition makes the ILDM quite accurate in description of the slow system dynamics, but for fast motions, which become very important in the context of ignition/extinction problems, there are up to now no reliable methods based on ILDM. Therefore, the current work is devoted to developing such a method which can be used efficiently for global analysis of the reaction mechanisms with subsequent formulation of explicit reduced models for unsteady combustion regimes like ignition processes. The suggested method is illustrated by a simple Lindemann kinetic model and then applied successfully to the auto ignition of a homogeneous n-heptane/air system.