Design and performance evaluation of bluff bodies for NOx mitigation in non-premixed hydrogen flames

This study investigates the impact of bluff body shape on flame steadiness and NO x (Nitrogen Oxides) emissions in non-premixed hydrogen-air combustion. Three bluff body shapes—flat, concave curved, and concave sharp burners—are numerically analyzed using the k-ε turbulence model with the turbulence-chemistry interaction model of finite rate/eddy dissipation. The goal is to optimize flame stability and minimize pollutants. Results show that the flat burner reaches a maximum temperature of 1679 K near the surface, leading to higher NO x emissions. In contrast, the concave curved and sharp burners exhibit lower peak temperatures of 1571 K and 1568 K, respectively. The flat burner also shows higher thermal NO molar reaction rates—85.71% and 92.85% higher than the concave curved and sharp burners. The concave sharp burner proves optimal, offering stable combustion with enhanced air-fuel mixing and reduced NO x emissions.