Hydrogen staging effects on flame stability and emissions in a fuel-flexible combustor

This study investigates the impact of fuel split between Jet-A1 and H$_2$ in a novel low-swirl combustor designed for low NO$_x$ emissions and flashback resistance. The combustor combines airblast atomization for Jet-A1 with H2 injection in a jet-in-crossflow configuration. Full and staged-injection strategies were examined experimentally at atmospheric pressure and elevated air inlet temperatures. The flame remained predominantly lifted up to 100% H$_2$ in full injection. Fuel staging enhances stability, extending the pure-H$_2$ lean blowout limit by a factor of 2.0 at 673 K and 1.6 at 473 K (air inlet temperature) compared with full-injection operation. NO$_x$ emissions remain below 15 ppm, with full injection advantageous at full-load and staged injection at part-load. CO emissions decrease substantially even with a modest 15% H$_2$. Non-reactive simulations complement the experiments, providing insight into flow and mixing fields for both injection strategies. These findings demonstrate that full and staged injection jointly enable low NO𝑥 emission and improved stability limits.