The structure of a confined swirling gas diffusion flame is numerically simulated. Reynolds-averaged governing transport equations for continuity, momentum and energy are solved. Both the turbulence and combustion process are modeled considering RNG k-ɛ model and steady diffusion flamelet model along with San Diego chemical kinetic mechanism respectively. Discrete Ordinates (DO) radiation model as well as the weighted sum of gray gases model (WSGGM) are considered for predicting gas radiative properties. Its effect is included as a source term in the energy equation. Suitable boundary conditions are considered in compliance with the axi symmetric configuration. The predicted axial distribution of the heat flux shows a good agreement with the experimental measurements. The results show that, with the increase in the swirl number, the flame gets closer to the burner exit and becomes more compact and intense due to the enhancement in mixing by the swirl flow and the recirculation of hot products stimulated by the inner recirculation zone (IRZ). NOx emissions increase with the swirl number before the critical swirl number of 0.2, and decrease after the swirl number exceeds this critical value, which is attributed to the dilution effect by the recirculation of exhaust products back to the flame. CO emission increases noticeably with the swirl after the swirl number exceeds 0.7. Increasing combustion air temperature leads to higher negative axial velocities inside the IRZ, which improves mixing process and consequently combustion efficiency. Yet this does not affect the flame stabilization location with respect to the burner exit. The flame intensity is higher as well as the maximum heat flux. NOx emissions increases, while CO emission is lower, as the inlet temperatures exceeds 700 K. This work is important for improving flame stability and controlling flame characteristics to fit with different application