Hydrogen-Powered Annular Combustor Design and Aerothermal Optimization for a Short-Haul Large-Bypass Turbofan Engine

Commercial aviation contributes approximately 3% of global CO2 emissions, while nitrogen oxides (NOx) remain a major environmental concern. Hydrogen is a promising carbon-free fuel for future gas turbine engines and offers a potential pathway towards net-zero aviation. This study presents the aerothermal design and CFD-based iterative refinement of an annular combustor for a hydrogen-fuelled CFM56-class large-bypass turbofan. The combustor was initially sized using established design correlations, with GasTurb14 providing the engine-cycle boundary conditions. CFD simulations were performed to evaluate the airflow distribution, temperature field, pressure loss and NOx formation, and to optimize the cooling-hole arrangement. The final combustor achieved the target exit temperature of 1500 K with a pressure loss of 5.9%, meeting the design objective of approximately 6%. Relative to the initial hydrogen-fuelled configuration, the redesigned cooling-hole layout reduced the fuel-to-air ratio required to achieve the target exit temperature from 0.009 to 0.0073 (18.9%) and reduced the exit NO mass fraction from 0.003443 to 0.002223. A separate Large Eddy Simulation (LES) of the final combustor geometry was conducted to compare the combustion characteristics of hydrogen and Jet-A under identical operating conditions. The results demonstrate that cooling-hole configuration has a significant influence on combustor thermal performance and NOx emissions, providing design guidance for future hydrogen-fuelled gas turbine combustors. Owing to the absence of experimental data for this configuration, the results are presented as a computational design study supported by a benchmark comparison rather than as an experimental validation.