Session: 04-25 Combustion Dynamics - Hydrogen Flames I

Paper Number: 152010

Design of a Rich-Burn Hydrogen Micromix Injector for Investigating Entropy Waves 

The conversion of current state-of-the-art Rich-Quench-Lean (RQL) kerosene engine combustor technology to hydrogen fuel has the potential to contribute to the decarbonization of aviation. An open research topic in this context is the contribution of entropy waves generated in hydrogen flames to indirect engine noise.
In this work, a rich-burn hydrogen injector has been developed to study the entropy wave characteristics after the rich-burn zone and to measure entropy transfer functions over the burnout region downstream of the dilution air admission. A micromixing concept was chosen to generate a nearly planar flame sheet free of large-scale three-dimensional inhomogeneities to provide optimal conditions for planned experimental investigations with line-of-sight integrating optical diagnostics. The injector design was optimized with jet-in-crossflow correlations and 3D RANS incorporating conjugate heat transfer. The geometry was optimized with regard to temperature and mixture homogeneity for equivalence ratios between 1.0 and 1.4 at standard atmospheric pressure, and engine-representative combustor entry air temperatures. Important parameters investigated were flame length and lateral spread, the momentum ratio between the hydrogen and the air jets in the range between 0.3 and 3, the combustion chamber outlet profile homogeneity based on temperature, and the distribution of oxygen and unburnt hydrogen. It is shown that high momentum flux ratios lead to better mixing, shorter flames, and improved homogeneity at the combustor outlet. Burner material temperature is shown to increase primarily with air preheating temperature and to a lesser degree with equivalence ratio.

Presenting Author: Ángel Brito Gadeschi Technical University of Munich, Germany; TUM School of Engineering and Design, Department of Aerospace and Geodesy, Assistant Professorship of Sustainable Future Mobility

Presenting Author Biography: Ángel Brito Gadeschi got his master’s degree in aerospace engineering at the Technical University of Munich and has been working as a research assistant at the Assistant Professorship of Sustainable Future Mobility of TUM since July 2022.
Mr. Brito Gadeschi has a great interest in shaping the future of aviation. His research focuses on hydrogen combustion in aero engines. He combines numerical and experimental approaches to design a sequential hydrogen micromix burner with a rich-burn first stage and a lean-burn second stage.

Authors:

Ángel Brito Gadeschi Technical University of Munich, Germany; TUM School of Engineering and Design, Department of Aerospace and Geodesy, Assistant Professorship of Sustainable Future Mobility
Thuy An Do Technical University of Munich, Germany; TUM School of Engineering and Design, Department of Aerospace and Geodesy, Assistant Professorship of Sustainable Future Mobility
Agnes Jocher Technical University of Munich, Germany; TUM School of Engineering and Design, Department of Aerospace and Geodesy, Assistant Professorship of Sustainable Future Mobility