Effect of swirl number on structural and emission characteristics of moderate size burner flames

An experimental investigation was conducted on the flame characteristics, thermal properties, and emissions of industrial-scale (40 kW) diesel flames. This study uniquely measured structural (flame length, diameter, volume), thermal (temperature, heat flux), and emission characteristics (COX, NOX, Unburnt HC) across various equivalence ratios (0.2-0.6) and swirling conditions (Swirl number varying from 0.73 to 1.04). Results indicated that higher swirl numbers generally led to more stable and compact flames, though structural properties were less affected during lean combustion. Notably, flame temperature varied significantly, up to 350 K, resulting in substantial difference in specified emission products. The emission reductions were achieved, particularly with a geometric swirl number of 1.04, which balanced flame performance and emission both, achieving reductions in CO (9-97 %), HC (18-96 %), NO (8-16 %), and Smoke (0.3-82 %). These findings underscore the critical impact of swirl angle on combustion efficiency and emissions, highlighting the need for meticulous optimization to mitigate harmful emissions effectively. This study provides new insights into optimizing combustion parameters for enhanced environmental sustainability in industrial processes.