Assessment of the EDC/finite rate chemistry approach towards predicting extinction in a turbulent buoyant diffusion flame

Large eddy simulations with the eddy dissipation concept (EDC) combustion model, considering finite rate chemistry effects, are presented for fire-related scenarios (i.e., in the 'FM Global burner' test case). The considered reaction mechanisms are first studied in mixture fraction space, without the inclusion of transport terms in physical space, by means of a 0-D conditional moment closure (CMC) method. The focus of the work is on exploring the capabilities of EDC, combined with finite rate chemistry, towards capturing extinction phenomena in low strain, buoyant diffusion flames without the need of additional extinction criteria as needed with the use of fast chemistry. The considered scenarios involve cases with and without flame extinction as well as different fuels (hence, also various finite rate chemistry mechanisms). The predictive capabilities of simple reaction mechanisms is examined in a range of grid sizes, by comparison to experimental data for first and second order statistics. The results demonstrate that simple mechanisms predict both the temperature fields and combustion efficiencies reasonably well for the scenarios tested (10% relative deviation). Furthermore, the addition of more reactions and species (i.e. going to more detailed reactions) does not necessarily improve the results for the flames at hand.