Prof. Dr. Thomas Sattelmayer
Technische Universität München
Lehrstuhl für Thermodynamik

Prof. Vincent McDonell
University of California, Irvine
Combustion Laboratory

Due to the absence of climate-damaging carbon dioxide emissions, combustion of hydrogen in gas turbines contributes to sustainable power generation in the future. In this regard, the so-called lean premixed combustion proved to be very successful in the past. Here, a lean mixture of fuel and air is prepared already before combustion, which then yields very low nitrogen oxide emissions during the combustion process. However, this technique involves the risk of uncontrolled flame flashbacks from the combustion chamber into the premixing region. This safety-critical phenomenon has been investigated in depth at both the Technische Universität München (TUM) and the University of California in Irvine (UCI). It turned out that the method of flame stabilization has a strong influence on the flashback propensity. The latter will be investigated systematically within this joint effort.

Final report:

In the framework of the cooperation a test rig for the investigation of flame flashback phenomena during premixed hydrogen combustion has been designed at the University of California in Irvine (UCI). In the past, differences in the flame flashback behavior have been observed in experiments conducted at the Technische Universität München (TUM) and at UCI, respectively, in spite of using very similar setups. Therefore, original components from TUM were integrated into the experimental infrastructure at the UCI in order to investigate this issue in detail. The experimental studies helped to clarify the observed differences and the flame flashback propensity for a variety of different burner configurations was determined. It turned out that the burner material and the temperature of the burner rim as well as the method of flame stabilization play a major role for the flashback propensity, whereas the burner diameter has negligible influence. To provide for safe burner operation, a narrow confinement of the flame has to be avoided and at the same time the heat transfer from the burner rim should be maximized. In the future, a more general accounting for burner tip material and overall heat transfer will be investigated along with the influence of acoustic instabilities, which could potentially lead to confined flame situations. In addition, the role of elevated pressure on flashback propensity will be evaluated. In summary, future work will bridge the basic understanding of flame flashback to practical systems.