Characteristics of Hydrogen-Piloted, Premixed Ammonia/Air Flames in a Swirl-Stabilized Gas Turbine Can Combustor: A Numerical Study

Alternative fuel blends consisting of ammonia and hydrogen are now actively being considered in gas turbine combustors for power applications, as this is a potential way to achieve the net-zero goal in the coming decades. In this regard, the present research work focuses on numerically studying the combustion characteristics of hydrogen-piloted ammonia/air flames in a gas turbine can-combustor setup that is equipped with an industrial premix low-NOx swirl burner (SoLoNOx). Although the burner was originally designed and previously used for hydrocarbon-based fuel, in this research work the operational flexibility of the burner was investigated with zero-carbon fuels such as ammonia and hydrogen. A computational model of the combustor setup was created using SolidWorks and numerical study was performed under steady state conditions using the CONVERGE CFD 3.0 software. Using this software, turbulence and premixed combustion were modeled using the RANS RNG k-epsilon technique and the SAGE detailed chemical kinetic solver, respectively. Characteristics such as temperature, velocity and emissions were studied for different cases at equivalence ratio =0.6 and Reynolds number =50000; These cases were different with respect to their air inlet temperature and pilot fuel %. A suitable chemical mechanism from the literature consisting of 263 reactions and 38 species was used. The study found that SoLoNOx burner can be fuel-flexible under certain conditions. Preheating was found to be one of them which helped stabilize the hydrogen-piloted ammonia flame. This was possible because preheating was found to increase the extent and intensity of recirculation zones, thereby improving flame stabilization and combustion efficiency.