SHORT-LENGTH SCALE PRESSURE PULSE INTERACTIONS WITH PREMIXED FLAMES

The wave equation for pressure waves is considered in the presence of a strong temperature gradient due to the interference of a flame. The characteristic length scale of the pressure wave is of the order of the typical diffusion length scale in the combustion zone so that the temperature gradient, has a significant effect on the progress of the wave. In this paper the progress of pressure pulse and step function type inputs interacting with the flame is considered, and in particular the effect of the steep temperature rise is monitored for different pulse thicknesses and varying steepness of pressure rise (in the case of step function type inputs). It is shown that sharp pressure changes (where in rough terms ''sharp'' means that the major change takes place well within half the 99% temperature fisc distance of the initial steady temperature profile) induce quite a strong deformation to the reflected pressure wave which should be possible to observe experimentally.