Global energy demand has seen a significant increase over the past 70 years, accelerating greenhouse gas emissions by placing excessive pressure on existing non-renewable energy sources. As wind and solar power are projected to account for a significant share of future electricity production, their intermittent nature introduces a major challenge to grid stability. Green hydrogen offers a promising solution as it can be produced during periods of excess electricity supply and combusted in land-based gas turbines during high electricity demand, thereby stabilizing any oscillations. Combustion of hydrogen is, however, not problem-free. The main challenge is its high flame speed, which can lead to flashback, an undesirable upstream flame propagation that can cause damage to the combustor hardware. Because conventional land-based gas burners are not designed for pure hydrogen combustion, new burner designs must be developed and tested. An example of such a burner is the FlameSheet™ burner, whose geometrical simplification, called a 2-D trapped-vortex burner, is investigated in the present experimental study.

The structure of this study can be divided into two parts. The first part investigates the flashback behavior of the 2-D trapped-vortex burner for a range of equivalence ratios, hydrogen volume fractions, and unburned mixture temperatures. The results show increased flashback propensity with all three parameters, although the Reynolds number at flashback seems to be invariant with the last. The second part examines temperature profiles within the 2-D trapped-vortex burner, with a particular emphasis on their dependence on the Reynolds numbers, unburned mixture temperatures, and adiabatic flame temperatures. The thermocouple measurements reveal that the temperature profiles shift toward lower values with increasing Reynolds numbers and higher values with increasing adiabatic flame temperatures. To complement these findings, a one-dimensional heat transfer model is developed, which not only predicts the vertical temperature profiles in the remaining components but also identifies convection and conduction through the liner as the dominant and limiting heat transfer mechanisms.