Large-eddy simulation and experimental study of a partially premixed hydrogen / air swirled burner: impact of the injection system
Résumé
To control flashback, two solutions are considered. The first is to operate in a non-premixed flame regime, but this solution generates the largest NO emissions. Nevertheless, it guarantees the prevention of flashbacks. The second solution is to operate in a partially premixed regime. Here, the goal is to achieve optimal mixing between the fuel and air in a very short time and at the smallest distance. If this mixing condition is met, the combustion will produce minimal nitrogen monoxide (NOx) akin to fully premixed combustion, with the benefit of avoiding any flashback.
The objective of this study is to assess the impact of the hydrogen-air mixture quality in a swirled bluff-body burner with modifiable injection geometry, on the topology of the stabilized flames as well as on pollutant formation. Comparisons of results from large-eddy simulations with measurements allow to validate the results, in terms of aerodynamic field, flame shape and position. Further analysis of the LES results show that the centripetal injection yields a more uniform air/hydrogen mixture. This also leads to a reduction in the maximum temperature, subsequently contributing to lower emissions of NOx.