Influences of momentum flux ratio and fuel injection on flame stabilisation in a lean direct injection burner

Hydrogen is a promising fuel to achieve decarbonisation targets. Its broad flammability range compared to hydrocarbons allows fuel-leaner operations, which can help to mitigate thermal nitrogen oxides formation. The lean direct injection combustor (LDIC) configuration with multiple injection of fuel into crossflowing air, is one of the potential frontrunners for 100% hydrogen combustors. While the LDIC can reduce flashback risk, the global flame features are not well understood. Large Eddy Simulation (LES) with a subgrid-scale partially premixed combustion model with tabulated chemistry is employed to study the fundamental mechanisms in lifted or attached flames. The computed mixture fraction statistics in non-reacting flow and flame attributes compare quite well with measurements. The time-averaged statistics are investigated to shed light into the effects of injector count and momentum flux ratio on fuel–air mixing and global flame behaviour. It is demonstrated that the major parameter influencing the fuel distribution and flame behaviour is the jet-to-crossflow momentum flux ratio based on the individual fuel jet. The number of injectors (that are placed diametrically opposite to each other) has minimal influence on the mixture distribution of individual fuel jets but influences the flame length.