Large-Eddy Simulation of the Internal Multiphase Flow of an Additively Manufactured Research Burner for the Flexible Use of Hydrogen, Ammonia and Liquid Methanol

This study presents a Large-Eddy Simulation (LES) of the multiphase flow in a novel, additively manufactured research burner for the flexible use of hydrogen, ammonia, and liquid methanol as fuels. This combination of fuels will reduce the carbon dioxide emissions from the combustion process. The simulations are performed to assist the development of the novel burner and to identify the inlet conditions for the flow field. The burner incorporates an ultrasonic atomizer for the atomization of the methanol. The spray is carried by gaseous ammonia. H2 micro-combustion sites are located in the upper part of the burner to enhance the ammonia combustion. The complex flow field of the multiphase flow inside the burner is investigated using an LES to analyze the velocity profiles, species distributions, and the interaction of the spray with the gas. Key results include the occurrence of a recirculation zone near the atomizer with influences on the spray droplet trajectories. The LES shows that the addition of a second air inlet, combined with the repositioning of the ammonia inlet position and enlarging of the internal inflow channel of the hydrogen rings in a somewhat burner design, leads to a more uniform hydrogen distribution, even at low hydrogen flow rates. This study demonstrates the importance of computational fluid dynamics for guiding the development of an innovative carbon-neutral, fuel-flexible burner by analyzing the flow field characteristics inside the burner prior to manufacturing the burner and studying the combustion process.