Skeletal mechanism generation for high-temperature oxidation of kerosene surrogates

Abstract

A skeletal mechanism with 106 species and 382 reactions is developed from a detailed kerosene combustion chemical kinetic mechanism that includes 209 species and 1673 reversible reactions for a tricomponent surrogate mixtures, consisting of n-decane, n-propylcyclohexane, and n-propylbenzene. The directed relation graph (DRG) method for skeletal mechanism reduction is applied as the first step for reduction of mechanisms with large numbers of species. A revised DRG approach (Z.Y. Luo, T.F. Lu, et al., Energy Fuels 24 (2010) 6283–6293) is compared with the original one and it is shown to be more stable than the original DRG method. The simplified iterative screening and structure analysis method (ISSA) is used subsequently based on the reduced mechanism generated by the DRG method to remove redundant species and reactions simultaneously. A minimal skeletal mechanism from the detailed mechanism for kerosene combustion is thus obtained. It is found that the discrete local reaction rates rather than the time-averaged reaction rates should be adopted when using the ISSA method for mechanism reduction due to large temperature difference and different reaction pathways in combustion at different simulation conditions. Although reduced in size by a factor of 2 for species and a factor of 4 for reactions, the skeletal mechanism exhibits high accuracy for high-temperature applications in predicting global combustion parameters, such as ignition delay, detailed profiles of species concentrations, and laminar flame speed. Furthermore, numerical simulation results of different mixture compositions are also comparable with those based on the detailed mechanism, indicating that the major reaction pathways of each component are captured by the reduced mechanism and the hierarchical structure of the detailed mechanism is maintained.