Premixed flame response to oscillatory pressure waves

We numerically investigate the interaction of sinusoidal pressure waves and slightly corrugated premixed flames. Work up to now has demonstrated the well-known Rayleigh–Taylor instability by imposing a single pressure ramp function onto a corrugated premixed flame. This paper considers sinusoidal oscillations of pressure. Such inputs are important since observations of large-scale experiments suggest that the presence of acoustic waves might be expected to have a significant influence on the propagation of the flame. The numerical experiments reported in this paper show that oscillatory pressure waves of the order of 800 Hz can have a magnifying effect on the wrinkling of the flame, due to the effect of Rayleigh–Taylor instabilities, hence increasing the overall mass burning rate, and that a sinusoidal pressure wave interacting with a premixed flame causes the flame to increase its wrinkling with every cycle in pressure. The result of great interest is that this growing process reaches a maximum after a few cycles, creating a dynamic equilibrium in which the final time-averaged mass burning flux is larger compared to that of the initial flame. It is also shown that the final mass burning flux increases with amplitude of the pressure wave, and increases with increasing frequency over the range explored.