Flame Characteristics of NG Combustion on Innovative Spiral Bluff Body Axial Burner

This research focuses on improvement of the natural gas combustion characteristics on a non-premixed inverse diffusion flame (IDF) axial burner. Following the previous research, a smooth port IDF axial burner (referenced burner) was developed by investigation of spiral bluff body on axial burner. This study employs both mathematical modeling through Ansys Fluent 2021R2 software and experimental investigations. For improvement of combustion characteristics, the size and firing rate of referenced IDF burner were studied to enlarge for further burner improvement by similarity analysis. At equivalence ratio 1.0, IDF burner could be enlarged between firing rate 2.0-10.0 kW whereas the same combustion characteristics were obtained. To improve natural gas combustion characteristics such as flame temperature, temperature distribution and flammability limit on axial burner, the 4.0 kW firing rate of axial burner was suitable to apply for simulation and experimental study. Three models of bluff body are spiral bluff body with diameters of 8 mm (SB8), 10 mm (SB10), and 12 mm (SB12) on air-port burners were applied at equivalence ratio 1.0. The simulation results showed the highest flame temperature on SB12 models compared to smooth SB8, SB10 and referenced models. As the experimental results, the flame quenching was observed on SB12 design and the highest flame temperature with widest flammability limit (Eq.=0.7) were obtained on SB10 design. Consequently, the spiral bluff body could improve flammability limit and flame temperature as the combustion characteristics.