Effect of hydrogen injection on the stability of non‐premixed methane/air flame in a gas turbine combustor

The trend towards cleaner combustion in gas turbine engines has led them to dynamic instabilities of the flame. To mitigate this, one strategy is to enhance the flammability limit of the base hydrocarbon fuels by adding hydrogen. The addition of hydrogen further creates instabilities due to its increased flame speed and higher diffusion rate than the base hydrocarbon fuels. In this paper, three different models are considered to analyze the effect of hydrogen injection on the stability of methane/air flame. Scale Adaptive Simulations (SAS) paired with Flamelet Generated Manifold (FGM) models are considered for both the baseline and hydrogen‐injected cases. A DLR gas turbine model combustor, operating using a stable flame at 35 kW was used as a baseline case. The results show that the addition of hydrogen leads to appearance instabilities within the flame, extinction and re‐ignition within the gas turbine combustor, creating a cycle of flashback. This may be due to the increased laminar flame velocity of hydrogen and the sensitivity of the flame to initial flow perturbations. The results further conclude that the SAS turbulence model coupled with the FGM chemistry model better corresponds with the experimental data. Thus, in order to use hydrogen for cleaner combustion of hydrocarbon fuels, an efficient and accurate injection rate is needed to design more robust gas turbine engines.