A numerical and experimental investigation into the mixing mechanism of hydrogen transverse jets into an air swirl flow

As a clean fuel with the advantages of abundant reserves, high calorific value, renewability, and zero carbon emissions, hydrogen has broad application prospects in the fields of energy and power. Moreover, the mixing characteristics of hydrogen and air play a crucial role in determining combustion performance. A novel mixing method of hydrogen transverse jets into an air swirl flow was investigated via numerical and experimental approaches. The Schlieren technique and high-speed photography were employed in the experiments. The effects of various swirl numbers and jet momentum flux ratios on the flow field structure, its transient characteristics, and mixing properties were studied. The research results indicate that the complex vortex structure in the mean flow field is jointly affected by the swirl number and the jet momentum flux ratio. An increase in the jet momentum flux ratio has distinct effects on the flow unsteadiness for different swirl numbers, and there exists a critical value of the jet momentum flux ratio that substantially affects the degree of mixing and a characteristic length suitable for normalization of the axial coordinates when describing the centerline concentration decay. This study provides a reference and basis for further research on combustion in air swirl flows of hydrogen transverse jets.