Flame stability analysis of premixed hydrogen/air mixtures in a swirl micro-combustor

A swirl micro-combustor for premixed hydrogen/air flames is proposed to improve flame stability. The swirl micro-combustor consists of a cylindrical combustion chamber and an inlet section where a swirler with 6 straight vanes at an angle of 45° is placed in an annular inlet duct. The flame stabilization mechanism and combustion characteristics at different velocities, equivalence ratios, and solid materials are analyzed using three–dimensional numerical simulations. The results indicate that the role of the inner recirculation zone on flame anchoring is dominating while the corner recirculation zone is favorable to the preheating effect. The coupling of the heat recirculation from the solid walls and the recirculating flow in the recirculation zones contributes to the improvement of flame stability. Increasing inlet velocity weakens the preheating effect. The flame temperature, combustion intensity, and preheating energy increase with an increasing equivalence ratio. The preheating effect is enhanced by using highly thermally conductive materials, thereby facilitating the initiation of the chain reactions.