Numerical Study of Fuel Injection Numbers Effects on Flame Temperature and Emissions in a Semi-Premixed Burner

In this study, the effect of fuel injection port number on flame temperature distribution and pollutant formation in an industrial semi-premixed burner is numerically investigated. Since turbulent mixing plays a dominant role in controlling flame structure and thermal NO formation, three configurations including single, three and five-port injection were analyzed under identical operating conditions. Three-dimensional steady simulations were performed using the finite volume method in ANSYS Fluent. Turbulence was modeled using the standard k–ε model, combustion was described by the Eddy–Dissipation model within the Species Transport framework, and radiative heat transfer was incorporated using the Discrete Ordinates (DO) model. Thermal NO formation was considered based on the Zeldovich mechanism. Results indicate that increasing the number of injection ports enhances lateral flame spreading and improves temperature uniformity. The maximum flame temperature increased from approximately ۱۷۰۰ K in the single-port configuration to nearly ۱۹۰۰ K in the five-port case. While NO mass fraction increased to about ۶×۱۰⁻⁵ in the five-port configuration, CO levels were significantly reduced compared to the single-port case. The findings demonstrate that multi-port injection improves combustion completeness, although simultaneous control of peak temperature and NO formation requires optimized geometric design.

کلیدواژه ها:

Semi-premixed burner ، Numerical simulation ، Combustion pollutants ، Fuel–air mixing ، Thermal NO formation