Application of Detailed Chemical Kinetics to Combustion Instability Modeling

A comparison of a single step global reaction and the detailed GRI-Mech 1.2 for combustion instability modeling in a methane-fueled longitudinal-mode rocket combustor was performed. A single element shear-coaxial injector was operated under two different conditions corresponding to marginally stable and unstable operation in order to evaluate the performance of the chemical kinetics mechanisms on combustion stability. Results show improved prediction in the frequencies and amplitudes with the detailed kinetics but the underlying source of the instability phenomena remains the same. In contrast to previous two-dimensional results, these three-dimensional results demonstrate that the present non-premixed injector configuration is primarily mixing-controlled and that the global chemical kinetics are sufficient to capture the stability characteristics.