Numerical investigation of combustion instability and flashback of lean-premixed low-swirl hydrogen jet flame

As an eco-friendly combustion method, lean-premixed hydrogen combustion is attracting attention since lean-premixed hydrogen combustion has the advantage of significantly reducing NOx emissions and emitting no CO2. However, the lean condition is particularly prone to combustion instabilities (CI) and flashback, which can cause severe damage to combustors. In this study, the effects of the equivalence ratio on the CI and flashback of a lean-premixed hydrogen jet flame in a low-swirl combustor (LSC) are investigated using Large-eddy Simulation employing Dynamic Smagorinsky Model and Dynamically thickened flame model as a turbulence and turbulent combustion models, respectively. The results show that the amplitude of the pressure oscillations increases significantly when the spatially averaged temperature inside the combustor reaches a certain temperature, and that flashback tends to take place under a certain combustion condition.