Numerical simulation of turbulent non-premixed flames

It is almost two centuries that we are using fossil fuels as our main energy source. Within the last fifty years, the consumption of fossil fuels, and consequently the pollution caused by the combustion process increased drastically which and led to serious environmental and health issues. Controlling these pollutants and reducing them is our only key to survival. The main goal of this thesis is to create a comprehensive 3D CFD model using the commercial software ANSYS FLUENT based on the available database of the University of Sidney on a bluff-body burner using CH4/H2 as fuel. The computed results have been compared with measured temperature, mean mixture fraction, and species mass fraction. The model is based on the non-premixed combustion by getting advantage of the steady flamelet model and the chemical equilibrium combustion model. The realizable k-ε model is modified by changing the ε equations constant, and the results are compared with the Standard model to investigate the turbulence model’s effect on the numerical predictions. In order to model the combustion, a detailed kinetic library of methane is used to mimic the methane combustion and NOx formation as close as possible to the real combustion process, and the combustion model sensitivity is measured. The whole developed model is applied to another flame with different blow-off velocity, and the results are compared with experimental data. The studies performed and reported in this work suggest that the realizable k-ε combined with the steady flamelet model can predict the combustion with a high degree of accuracy.