Linear instability of a premixed slot flame: Flame transfer function and resolvent analysis

The response to forcing of a 2D laminar premixed slot flame is investigated by means linear analysis, based on the compressible flow equations with two-step reaction scheme for methane combustion. transfer function (FTF) computed from this model, in excellent agreement reference nonlinear calculations. input-output gain between externally applied and global heat release rate computed, peaks are related intrinsic thermoacoustic (ITA) modes. receptivity arbitrary characterised resulting amplitude fluctuations. Linear resolvent analysis used identify optimal structures their associated response, leading discussion dominant mechanisms amplification perturbations, which trigger oscillations. These seem involve resonance ITA instability