Experimental and computational studies of soot emission in a gas fuelled swirl stabilized combustor

The present study is concerned with measuring and simulating soot and flame structure of a non-premixed gas fired swirl stabilized combustor incorporating a two-step soot model. Soot mass fractions have been measured by gravimetric method. Fluent CFD software has been employed for numerical predictions and the effect of two combustion models on flame structure and soot production are investigated. Both finite rate model with eddy-dissipation concept and flamelet approaches are employed to model the combustion process and the accuracy of each model is compared with the experimental data. In terms of turbulence modeling, the full Reynolds stress transport model is employed to calculate the turbulent characteristics of highly swirling flow. Measurements and computations are performed for different cases by varying the equivalence ratio, the inlet air temperature and the combustor wall temperature. The numerical predictions and experimental measurements show that soot generation strongly depends on the equivalence ratio and the inlet air temperature, as well as it is also affected by the combustor wall temperature. The numerical results show the significant influence of combustion models on soot formation/oxidation, when investigating the non-premixed natural gas/air flame. The comparison of calculated results against the experimental measurements for rich combustion reveals the superiority of flamelet model over the finite rate model.