Session: Student Poster Competition

Submission Number: 176439

Reduced-Order Kinetic Calculations of Water-Diluted Hydrogen Combustion at Aeroengine Conditions 

Hydrogen is a promising zero-carbon fuel for aviation gas turbines. However, its practical use in modern aeroengines faces challenges such as high operating temperatures and flashback. Liquid water injection has emerged as an approach to address these issues, providing local cooling and dilution of reactants at the flame front as well as chemistry-related effects and interactions with the flame surface, which can suppress emissions while enhancing the stability of hydrogen flames. This work investigates the impact of water injection on key combustor design parameters relevant, for example, to lean premixed combustor technology. Fundamental combustion parameters are explored in terms of mixture and spray characteristics through reduced-order calculations, such as 1-D freely propagating flames and 0-D reactors. Thus characteristics of water-diluted hydrogen flames, such as laminar burning velocity, flame temperature, and NO_x emissions levels, are compared to those of jet fuel at engine-relevant operating conditions representative of idle, cruise, and takeoff.

Freely propagating flame simulations of steam and liquid water-diluted hydrogen-air mixtures were performed using the computational fluid dynamics code CHEM1D. The implementation of one-dimensional flames considers liquid-gas interactions using an Eulerian-Lagrangian approach and the two-way coupling between phases with a detailed chemical mechanism. The Abramzon-Sirignano evaporation model was used and the Hirschfelder-Curtis approach was chosen to account for multicomponent diffusion. The effect of liquid loading and water droplet diameters on flame characteristics such as laminar burning velocity and flame structure was evaluated. Additionally, droplet evaporation timescales were compared with the chemical timescale, providing a metric to identify spray and mixture conditions in which more pronounced droplet-flame interactions may occur.

Additional calculations were performed with the open-source simulation package Cantera, considering only steam-diluted hydrogen-air mixtures — i.e., without liquid — as well as kerosene-air mixtures. Equilibrium calculations and adiabatic flame temperatures were initially evaluated. For the homogenous autoignition problem, ignition delay times were estimated in a homogenous constant-pressure reactor. An adiabatic, steady-state well-stirred reactor model with constant pressure was also used to investigate the impact of mixture conditions and residence time on NO_x emissions and flame temperature. Overall, the results indicate that even modest water additions (approximately 5% in volume of the mixture) can reduce flame temperatures and laminar burning velocities to levels compatible with modern gas turbine requirements within the range of operating conditions investigated.

Presenting Author: Gabriel Paganini University of Sao Paulo

Presenting Author Biography: Graduated with a bachelor's degree in Mechanical Engineering from the University of São Paulo (Brazil), where I gained hands-on experience in experimental rocketry as part of the extracurricular group Projeto Jupiter. Through a double degree program, I also earned a Master of Science in Aeronautical Engineering from École Centrale de Lyon (France), which included two internships periods at Safran Aircraft Engines. I am currently pursuing a Master of Science in Mechanical Engineering at the University of São Paulo, focusing on water injection in hydrogen flames for aeronautical gas turbine applications.

Authors:

Gabriel Paganini University of Sao Paulo
Fernando L. Sacomano Filho University of Sao Paulo
Pedro Magalhães De Oliveira University of Sao Paulo