Experimental and numerical investigation of the combustion behavior in a conical vortex combustor

In this study, we analyzed the effects of different excess air coefficients (α) and primary air ratios (φ) on the combustion process in a conical vortex combustion chamber. Experimental and simulation results revealed the significant impact of the variations in these factors on the flame shape, NO emission, and CH₄ residue in the combustor.

Three flame shapes were observed in the combustor at different air-flow rates. At 0.221 < α ≤ 1.21, outer trumpet-shaped flames formed in Case 1. At 3.57 ≤ α ≤ 10.61, the air influx through the vortex flow channel rapidly propagated to the lower part of the combustor, forming only the central flame in Case 3. At 1.21 < α < 3.57, the proper amount of air lowered the combustion temperature and increased the combustion area, and thus, outer trumpet-shaped and central flames coexisted in Case 2. In Case 2, the CH₄ residue was 0.8 % of that in Case 1, and the minimum NO emission was less than 40 ppm, providing a good balance between combustion and low-emission performance. These findings are expected to contribute to the development of a new type of combustion chamber.