Performance and Emissions Evaluation of a Turbofan Burner with Hydrogen Fuel

This paper examines the changes in the performance level and pollutant emissions of a combustion chamber for turbofan engines. Two different fuels are compared: a conventional liquid fuel of the JET-A (kerosene) class and a hydrogen-based gaseous fuel. A turbofan engine delivering a 70 kN thrust at cruise conditions and 375 kN thrust at takeoff is considered. The comparison is carried out by investigating the combustion pattern with different boundary conditions, the latter assigned along a typical flight mission. The calculations rely on a combined approach with a preliminary lumped parameter estimation of the engine performance and thermodynamic properties under different flight conditions (i.e., take-off, climbing, and cruise), and a CFD-based combustion simulation employing as boundary conditions the outputs obtained from the 0-D computations. The results are discussed in terms of performance, thermal properties, distributions throughout the combustor, and of pollutant concentration at the combustor outflow. The results demonstrate that replacing the JET-A fuel with hydrogen does not affect the overall engine performance significantly, and stable and efficient combustion takes place inside the burner, although a different temperature regime is observable causing a relevant increase in thermal NO emissions.