Our assistant professorship was represented at this year's Flammentag 2025 in Paderborn with the latest research findings on hydrogen-powered RQL combustion chambers. Both presented studies focused on the importance of secondary air injection. On the one hand, its influence on nitrogen oxide emissions was analyzed, and on the other hand, its influence on the experimental characterization of thermoacoustic instabilities.
- Maximilian Aubel investigated the optimization of nitrogen oxide emissions in hydrogen-powered rich-quench-lean (RQL) combustion chambers. Experiments on an atmospheric test burner were carried out using OH* chemiluminescence and NOx measurements. By varying the air split ratio, a local minimum of NOx emissions close to stoichiometric conditions in the primary zone was identified. This minimum represents the global optimum in relation to fuel consumption and indicates optimization potential for low-emission hydrogen RQL systems.
- Jannes Papenbrock investigated the application of an extended methodology for determining flame transfer functions in hydrogen-powered, application-oriented RQL combustion chambers. The extension of the classic method was proposed in Faure-Beaulieu et al. to measure the behaviour of RQL combustion chambers under lean primary zone conditions [1]. Experiments showed that the underlying assumption—that secondary air has no influence on the heat release rate—does not apply to flames that expand axially towards the secondary air injection. Optical investigations under acoustically excited conditions were used for verification and illustrate the need for further model adaptation to describe such flames.
We are delighted to have contributed to combustion research at Flammentag 2025 and are grateful for the lively and exciting professional exchange on site. We are already looking forward to the next Flammentag in Stuttgart in 2027.
[1] | Faure-Beaulieu, A., Dharmaputra, B., Schuermans, B., Wang, G., Caruso, S., Zahn, M., et al.: Measuring acoustic transfer matrices of high-pressure hydrogen/air flames for aircraft propulsion. Combustion and Flame, 270, 113776, 2024. |