Design and Numerical Investigation of a Swirl-Stabilized Hydrogen Burner for Aero Engine Applications

In recent years, the potential of hydrogen as an alternative fuel for the decarbonization of the aeronautical sector has been widely recognized in both scientific and industrial combustion communities. Due to its high reactivity and diffusion, the development of new technologies or the improvement of existing ones to safely and efficiently burn hydrogen, presents significant challenges. Furthermore, nitrogen oxides (NOx) formation is potentially enhanced, becoming one of the primary factors to address. In this study, a novel 100% hydrogen burner for aero engine applications is designed. The burner realizes a lean, nonpremixed, swirl-stabilized flame achieved with a coaxial triple swirler injector. The innermost channel supplies the fuel, while the two outer channels provide primary and secondary air injections, respectively. The desired injector's flow split and swirl numbers are first individuated exploiting the numerical results from Computational Fluid Dynamics (CFD) Reynolds-averaged Navier-Stokes (RANS) reactive calculations of a parametric simplified geometry, allowing the down-selection of a promising design point. An iterative procedure involving more detailed CFD RANS reactive calculations led to the final geometrical parameters and injector design. The burner is completed with the development of an effusion cooling plate for the dome surface, and validated with a CFD reactive Large Eddy Simulation (LES). The entire workflow is carried out under representative engine operating conditions. Additionally, a detailed LES calculation is performed on a scaled version of the burner operated at ambient pressure, in the perspective of the planned experimental campaign that will take place at Laboratory of Technology for High-Temperature (THT-Lab) of the University of Florence, with results that will be exploited for the test rig design and commissioning.