Computational Investigation of Burner Blockage Ratio Effects on Combustion Mode in Stagnation-point Reverse-flow (SPRF) Combustors

Sustainable combustion technologies are essential for reducing carbon footprints and harmful emissions. The stagnation-point reverse-flow (SPRF) combustor is a promising configuration for achieving ultra-low emissions through mild combustion enabled by strong internal flue gas recirculation. In this study, the influence of burner blockage ratio (BR) on combustion behavior and the transition between mild and conventional regimes is computationally investigated for a lab-scale SPRF combustor, comparing different computational model combinations for implementing the BR’s parametric study. The investigated BRs span from ۲.۱% to ۳۲.۳%, keeping the area of the annular air inlet the same to maintain the air inlet momentum and velocity. Results show that mild combustion—characterized by uniform temperature fields, suppressed peak temperatures, and spatially distributed reaction zones—is maintained up to a BR of ۹.۳%, yielding significantly reduced  emissions. When BR reaches ۲۴.۵%, the flow reorganizes into a conventional flame mode, with localized heat release and peak temperatures approximately ۲۵% higher, indicating a sharp increase in thermal  formation potential. The findings quantify the role of BR in controlling combustion regimes and provide a clear design guideline for optimizing SPRF combustors toward stable, low-emission operation.

کلیدواژه ها:

MILD combustion ، Stagnation-point reverse-flow (SPRF) combustors ، Burner blockage ratio ، Computational fluid dynamics ، Turbulence-chemistry interaction