This study investigates the impact of \(\textrm{CO}_2\) and \(\textrm{H}_{2}\textrm{O}\) dilution ratios on the characteristics of a premixed \(\textrm{C}_{3}\textrm{H}_{8}\) /air turbulent flame in a swirled burner at atmospheric pressure. High-fidelity turbulence resolution is critical for capturing transient flame stabilization dynamics and pollutant formation in swirling flows. Therefore, Detached Eddy Simulation (DES) is employed to resolve large-scale unsteady turbulent structures, while the Eddy Dissipation Concept (EDC) models turbulence-chemistry interaction, incorporating a new reduced kinetic model made up of 36 species and 166 reactions. The study explores five volumetric fractions of \(\textrm{CO}_2\) or \(\textrm{H}_{2}\textrm{O}\) dilution ( \(X_{\textrm{CO}_2/\textrm{H}_2\textrm{O}} = 4\%\) , 8%, 12%, 16%, and 20%), three swirl numbers ( \(Sn = 0\) , 0.6, and 1.05), and two equivalence ratios ( \(\phi = 0.8\) and 1). Validation against experimental data confirms the model’s accuracy in capturing flow fields and scalar distributions. The results show that \(\textrm{CO}_2\) addition significantly lowers flame temperature and alters its shape, resulting in a major reduction in \(\textrm{NO}_{x}\) concentrations at \(X_{\textrm{CO}_2} = 16\%\) . Dilution by \(\textrm{H}_{2}\textrm{O}\) does not reduce \(\textrm{NO}_{x}\) as noticeably, but still leads to somewhat more stable and thinner flames. Additionally, \(\textrm{CO}_2\) is more effective than \(\textrm{H}_{2}\textrm{O}\) in suppressing flame flashback. This work provides interesting insights for optimizing swirl-stabilized flames.
