Large Eddy Simulation of FLOX turbulent combustion

The flameless combustion, technique of reduction of nitrogen oxides (NOx), is characterized by a high intern flue gas recirculation. This one leads to a high dilution of the reactants and a concentration of dioxygen locally less important. Consequently, the temperature peaks in the combustion chamber decrease and the production of NOx is reduced. In those conditions, the reaction rates are lower and the fast chemistry hypothesis is not valid anymore. The chemical kinetics has a significant impact on the process of the reaction. Therefore, the turbulent-chemistry interaction is a key issue in FLOX (flameless oxidation) conditions. In order to understand the phenomenon of flameless combustion, the UMONS owns three furnaces with FLOX burners fed with air and gaseous fuel, for which it exists several experimental data sets. Up to now, only RANS simulations have been performed with reduced reaction mechanisms. The PhD thesis aims to realize numerical simulation of flameless turbulent combustion with the Large Eddy Simulation (LES) approach using OpenFOAM®. Therefore, the main objective of the research is to accurately model the flow and the combustion physics by carrying out complex multi-physics simulations (turbulence, detailed chemistry, radiation). The studied applications would be mainly FLOX furnaces. The current investigation concerns one of the UMONS furnaces (30 kW) because its dimensions (0.35 m x 0.35 m x 1 m) allow to investigate complex models while its configuration is similar to industrial furnaces (high internal recirculation, burner design, cold walls featuring the load). Moreover, useful comparisons could be made with experimental data and RANS results.