Development of a Smart Controller for Maintaining Dynamic Stability in Lean-Premixed Hydrogen-Fueled Micromixer Gas-Turbine Combustors

The stringent international policies governing the future rise in global temperature trigger the need for sustainable clean energy sources that meet the demands for quality of life and economic growth, while avoiding emitting greenhouse gases (such as CO2) into the atmosphere. Hydrogen (H2) can help tackling various critical energy challenges, including the mobility sector. The use of H2 as an energy carrier in mobility and utility applications is, thus, expected to increase significantly in the foreseeable future. One of the challenges associated with the use of H2 is its low density in gaseous form, which makes it challenging to store and transport it effectively in large quantities. Ammonia (NH3) is a feasible H2-carrier, as NH3 can be stored and transported in liquid form if pressurized to 11 bar only. Compared to H2, however, NH3 has significantly inferior combustion characteristics, in terms of the flame speed and heating value. NH3 is thus cracked to blends of hydrogen and nitrogen (H2/N2) at the utilization site to release the H2 prior to combustion. The combustion application can be fueled by an H2/N2 blend or pure H2, depending on the design and characteristics of the burner hardware. Another challenge associated with H2 use is that it is significantly more reactive than conventional hydrocarbon fuels, so replacing these fuels with H2 in existing lean-premixed (LPM) gas-turbine power-generation applications is expected to impact the dynamic instability of the combustion process. Dynamic instabilities in LPM combustion systems are a serious concern, as the associated fluctuations in combustor pressure can be large enough to induce severe hardware damage and/or flame flashback into the flow passages upstream of the combustor. The dynamic instabilities of LPM H2/N2/air and H2/air flames will be examined experimentally and numerically in a model gas-turbine combustor utilizing the state-of-the-art micromix technology of current operational utility gas turbines. The ratio of H2 to N2 in the fuel blend will be varied to effectively control and potentially mitigate the dynamic instabilities. The experimental and numerical data on dynamic instabilities will be utilized for the development of a smart controller to avoid these instabilities in H2-fueled gas turbines.