Model reduction and mechanism comparison of hydrogen/oxygen auto-ignition

The problem of reduced kinetic models for auto-ignition is revisited. The hydrogen-air system is considered in a wide range of system parameters and initial conditions. The Global Quasi-Linearization (GQL) method is implemented to study the slow/fast time scale separation. Accordingly, the rate equations can be split into evolution equations for the fast and slow sub-systems. It is shown that in this way reduced models reproduce the detailed kinetics with a high accuracy. Furthermore, it is shown, that the obtained invariant subspaces are weakly sensitive to the specific kinetic mechanisms. This means that results obtained for one kinetic mechanism can be applied to devise reduced schemes for other detailed mechanisms. This is verified by using the GQL from one specific mechanism for model reduction of five other well known detailed hydrogen/oxygen mechanisms. Although it is demonstrated for the hydrogen/oxygen mechanism as an example, this model reduction method can be applied to other complex combustion mechanisms without principle difficulties. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.