Deflagration fronts and compressibility

This paper seeks to bring together a number of results pertaining to the in teraction of pressure waves with premixed combustion fronts. Some of the ea rlier results concerning low-speed flames and acoustics are set in context with some of the later work, which is still being developed and which takes compressibility into account to a much greater extent. The interaction of low-speed flames with steep pressure drops shows a possible mechanism for f lame extinction, and the interaction with steep pressure rises indicates co nditions for rapid flame acceleration to fast convection-reaction driven de flagrations. This work demonstrates that the transient nature of fast flame s, with their corresponding acoustic and reactive acoustic zones due to tem perature singularities (blow up) occurring near the driving piston of such deflagrations, is very sensitive to imposed pressure disturbances. In a sep arate section at the end of this paper, we address the question of the ampl ification of long-wavelength acoustic waves reflected from fast deflagratio ns, where the entropy change across such fronts is significant, but where t he structure of the deflagration is uncertain.