Study On The NO_x Model In The Methane Turbulent-Jet Combustion System

The NO_x formation in combustion system is considered one of the main sources of air pollution. It is more and more important to investigate the processes of NOx formation and transfer. With the developing of computation science, the NO_x simulation has become one of the main tools in the pollutant study for combustion processes, so it is a necessary task to study the model and mathematics method for it. Until now, most of the reaction processes in the NOx model were expressed by simplified reaction processes instead of the elementary reactions. Most of the transfer processes were described with the temperature fluctuation PDF and concentration fluctuation PDF, few by the single parameter PDF or partial equilibrium limited velocity PDF. But most of the simulation results reported by the reviews before just the same as experimental results in the trends.Under the theoretical basis of mass transfer, heat transfer, momentum transfer, turbulence-reaction interaction, and considered the characteristic of radial jet, turbulent, fast reaction. This paper first chose the Realizablek -ε, Standardk -ω,Reynold Stress turbulence models and the eddy-dissipation velocity model to simulate the temperature field, velocity field and the production concentration field in the methane turbulent-jet combustion. The simulation results have been compared with the experimental data reported by the Sandia National laboratories, which indicated that the predicted results by Realizablek -εand Reynold Stress model were have great difference with the experimental data, only the results computed by the Standardk -ωmodel was in accordance with the experimental data, and in some completely reacted zone it was just the same as experimental data.With the detailed elementary reactions and the newly reported combustion rate constants. This paper proposed a new chemical dynamical NO_x formation model, and then coupled with the united PDF method, obtained a NOx formation model, which taken the turbulence fluctuation into consider. The simulation results by this new model were in good accordance with the measurement data, the deviation is under 5%. It can be seen that the new model proposed by this paper was much better than the equilibrium model and partial equilibrium model afforded by the FLUENT module.