The climate change has forced many combustion systems move away from hydrocarbon fuels. The strongest alternative fuel is hydrogen whose exhaust only emits water vapor. Therefore, many gas turbine manufacturers are developing 100% hydrogen-powered gas turbines. In switching the fuel, one of the major technical issues is flame flashback – the reactivity of hydrogen is so fast so that the flame propagates upstream of the fuel nozzle. Once the flame flashback happens that the fuel nozzle which is weak for high temperature can be burnt and the nozzle has to be replaced. The flame flashback would incur interruption of the operation as well as the huge replacing cost. To prevent flame flashback, gas turbine manufacturers are now switching nozzle types from swirlers to micro-mixers which is relatively more robust to flame flashback. Still, fundamental understanding on flame flashback is necessary to rule out the onset of flame flashback and optimize the nozzle to reduce the pressure drop. The current talk presents the recent findings on the dynamics on flame flashback on hydrogen flames. Premixed flame propagation in a turbulent boundary layer reveals the interaction between the flame propagation and the modification of approaching turbulent flows. Furthermore, the quenching distance of the flame can change by wall thermal characteristics of walls.

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