Experimental and Numerical Investigation of Hydrogen Combustion in a Dual-Swirl Burner for Aero-Engine Applications

Green hydrogen produced by electrolysis offers a high potential for reducing CO₂ emissions and thus represents a promising approach for the decarbonization of aviation. However, propulsion systems based on direct hydrogen combustion require modified fuel injectors and combustion chambers to account for the particular combustion characteristics of hydrogen. Engineering those modifications requires the acquisition of experimental and numerical tools especially suited for this task and in the end validating them in a suitable environment. In this context, hydrogen combustion and its numerical simulation are presented with a dual-swirl burner in an optically accessible atmospheric combustor as an intermediate step. To ensure safe operation and to reduce the risk of flashback, fuel and air are injected nonpremixed. Good flame stability and mixing, which leads to potentially low NO_x values, is achieved by introducing a swirling motion into the flows. In this study, the combustor is operated under atmospheric pressure at a globally lean equivalence ratio. Measurements of OH* radical chemiluminescence as well as infrared (IR) radiation as marker of the hot water vapor distribution have been carried out to identify the flame location and shape. The configuration is further analyzed by means of reacting large-eddy-simulations (LES). The comparison of the simulation results with the experimental reference data shows that the flame lift of height and global flame spread are correctly predicted by the simulation for both operating conditions. However, the combustion model does not precisely capture the flame stabilization mechanism, leading to a radial offset of the flame front.