Developing reduced kinetics using chemical reactor networks and sensitivity analysis

A reduced set of chemical reactions is one approach to model combustion using computational fluid dynamics (CFD), where representative species and reactions are solved using species transport equations. An advantage is that the reduced chemical kinetics can provide physical insight into the controlling reactions. However, it is not trivial to simplify the reaction system and ensure that the reduced mechanism can reasonably approximate the full mechanism. In this work, a sensitivity analysis based on a proposed chemical reactor network (CRN) system has been conducted and evaluated for the non-premixed bluff-body flame. The flame has been decomposed as small homogeneous reactors and networked with flow paths in the CRN. By quantifying the CRN results with the local sensitivity, the dependence of species concentration on reaction rate coefficients has been revealed, where the reactions with high absolute sensitivity values can be considered as the rate-limiting steps. In this way, a reduced chemical mechanism was created and simplified from the detailed GRI-Mech 3.0. Finally, the established reduced reaction mechanism was validated using CFD with the eddy-dissipation-concept model.