On the Phenomenon of Local Flow Reversal in Premixed Flames due to a Large Pressure Pulse

Abstract

ABSTRACT It has been shown that pressure waves can have a large effect on the burning rate of flames. For sharp changes in pressure, recent studies by Batley, Mcintosh and Brindley [2] have indicated that the mass flux is dependent on the origin chosen as the frame of reference. Consequently, the structure of the flame is altered by the passage of a pressure disturbance as gas flows at different rates through different locations of the flame. In this paper, pressure disturbances on the relatively slow diffusion time scale are studied. This is when τ ≈ 1 where τ is defined as the ratio of a typical diffusion time to a typical acoustic time. This formulation leads to equations for the flame evolution which are valid for pressure in the range 0 ≤ p ≤ 1 + 0( 17sol; 0). Numerical investigations are carried out on these nonlinear equations. Results indicate that for sufficiently large pressure drops, the structure of the flame alters significantly even for disturbances on the slower time scale. For pressure pul...