Influence of bluff bodies on lean premixed combustion and pollutant emissions: A numerical approach

The flame holder configuration can significantly affect the performance of a combustion system. In this study, the influence of fuel composition and bluff body geometry on the lean premixed combustion system performance indicators, including temperature, stability, NOx production, and unburned hydrocarbons, are numerically investigated. The premixed combustion of five pure hydrocarbon fuels, namely H2, CH4, C2H2, C2H4, and C2H6, is simulated using a three dimensional coupled stoichiometric-CFD model. The holder bluff body cross-section shape is varied to assess the impact of the flow patterns on the combustion parameters. The numerical model provided satisfactory agreement with experimental data for propane-air combustion. Results indicate that lighter fuels sustain higher combustion completion and higher flame stability. The bluff body shape significantly impacted temperature distribution and flame shape compared to the plate flame holder design, which produced a broad flame along the burner. The findings establish a relationship between bluff body geometry, enhanced flame stability, and the conditions that influence pollutant formation, providing a basis for designs that mitigate NOx emissions during stable operation at leaner equivalence ratios.