Effects of Inlet Configurations on Hydrogen Combustion in a Combustor Coupling Tangential Swirl and Multiple Jets

This study numerically investigates the flow structures, temperature fields, and NO emissions in a combustor coupling tangential swirl with multiple jets under six inlet configurations. The results show that the inlet configuration substantially alters the central recirculation zone (CRZ) and local recirculation structures, thereby governing fuel transport, turbulent mixing, flame stabilization, and pollutant formation. Axial hydrogen injection provides strong jet penetration and promotes fuel consumption; among these configurations, Case 3, employing alternating H2/air and air injection through the axial ports, achieves the highest hydrogen conversion efficiency of 98.92%. Premixed H2/air tangential injection (Cases 2 and 4) produces coherent recirculation induced by swirl, enhances mixing between fuel and air, and suppresses localized temperature peaks. Case 2 yields the lowest mean center plane temperature, 1756.7 K, and the lowest outlet NO concentration, 9.35 ppm. The OH and H2 distributions indicate that axial injection produces an upstream reaction zone and rapid hydrogen depletion, whereas tangential injection strengthens flame anchoring near the inlet but promotes radial fuel dispersion. Pure tangential hydrogen injection shifts the region of high OH concentration downstream and produces a distinctly elongated flame. Combined axial and tangential premixed H2/air supply produces a compound flow structure with intermediate CRZ length and reverse flow intensity. Case 6 exhibits the highest mean center plane temperature of 2201.6 K, an outlet temperature distribution factor of 0.03, and an outlet NO concentration of 12.37 ppm. Overall, the combined inlet configuration provides a favorable balance among hydrogen conversion efficiency, outlet temperature uniformity, sustained combustion, and NO emissions.