NOx Formation Reduction Using Primary Aeration in a Swirl Stabilizer Combustor

In this paper, the effects of swirling air and primary aeration on NOx production are numerically investigated. In this regard, a combustion chamber with two-dimensional axisymmetric geometry and non-premixed combustion is considered. The k–e Realizable model is adopted as a turbulence closure model. Also, the Presumed PDF and EDM models with Zeldovich mechanism are considered for combustion modeling. Comparisons of numerical results with available experimental data show that the PDF model is capable of predicting the combustion characteristics. Results show that for every swirl number a specific aeration exists that consequences the minimum NO emissions. As the result, the increase of swirl number in without aeration will lead first to an increase and then a slight decrease of combustion temperature and NO at the exit. The effect of aeration in constant stoichiometric ratio shows that, swirl number of 0.48 and 2.5% aeration, leads to the complete combustion and minimum NO emissions.