Large eddy simulation of Darmstadt multi-regime burner with eddy dissipation concept and finite rate model

The novel TU Darmstadt multi-regime burner constitutes a valid candidate to evaluate the performance of existing combustion models when premixed and non-premixed regimes co-exist simultaneously. The aim of this work is to investigate the premixed and non-premixed flame structure observed in such configuration via large eddy simulations while assessing the subgrid-scale chemistry model. The chemical source term is determined with the finite rate model based on the Arrhenius law combined with the eddy dissipation concept for the sub-grid closure. Two simulations are performed with OpenFOAM employing a reduced chemical kinetics mechanism and a detailed one. The numerical results are validated against the existing experimental data  and the conditional flame structure to the mixture fraction and progress variable is discussed. Furthermore, the computational singular perturbation (CSP) and tangential stretching rate (TSR) analyses are also conducted to examine the non-adiabatic effects due to the cold bluff-body at the inflow and describe quantitatively how the diffusive and convective transport processes are connected to the the chemical evolution of this complex system.