The current study examines the effect of chemical reaction mechanisms on prediction of thermal and dynamic fields in the combustion process. The computational domain is a confined combustor that is equipped with a coaxial swirling burner and radial fuel injection. The general aim is to enhance the numerical prediction of the swirling diffusion flames. Turbulence chemistry interaction is modulated by the RSM turbulence model, eddy dissipation, and PDF combustion models. The three-dimensional simulations are performed by a CFD tool and discredited by the finite volume method. The numerical results validated with experimental data indicate that the PDF model gives a more accurate prediction of maximum flame temperatures with a relative error of 1.07% versus 4.07% for the eddy dissipation model. These results demonstrate the ability of the RSM-PDF combination to resolve velocity, temperature, and species distributions and, hence, to contribute to more accurate combustion modeling for other industrial applications.