A strategy based on hybrid 0D Chemical Reactor Networks and 1D Flame predictions for flashback prevention in an original H2 fueled micro Gas Turbine combustor without any redesign

Hydrogen combustion is well-known to lead to flame instabilities, potentially resulting in flashback. Performing air humidification or Exhaust Gas Recirculation (EGR) alters the combustor inlet conditions, slowing down the flame speed and reducing the reaction rate and temperature. Nevertheless, these solutions are currently less considered for safe hydrogen combustion, and no prediction methodology exists. Therefore, the main goal of this work is thus to provide a fast prediction and low-computational complexity methodology to prevent flashback in a micro Gas Turbine (mGT) without any combustor redesigning. A parametric study is thus performed to find the minimal dilution levels to lead to stable combustion for several CH4/H2 blends, using a hybrid model, combining a 0D Chemical Reactor Network with 1D laminar flame calculations. The 0D/1D approach allows predetermining the inlet conditions to reduce the laminar flame speed down to the one of pure methane combustion flame. The results obtained using this hybrid methodology show that safe and complete combustion is possible for 0 to 100% hydrogen when performing water dilution, but limited to 50–55%vol when performing EGR. The 0D/1D analysis shows that a CH4/H2 blend of 50/50%vol requires either a water-to-air ratio of Ω=3.4%, or an EGR ratio of 77 % for flame stabilization. Burning up to 100 % H2 involves Ω=10.25%, while no solution exists when performing EGR.