Dynamics of Premixed Flames

Abstract

Let us consider the motion of flame fronts in flows that can be unsteady and non-uniform. When the length and time scales of the initial flow are larger than those associated with the planar flame (the flame thickness d and the transit time d/u_o where u_o is the laminar flame speed), the flame front can be considered, in first approximation, as a surface of discontinuity whose the motion is controlled by two distinct factors: the normal burning velocity u_n associated with the mass flux of fresh mixture crossing the front and the value at the front of the flow velocity field. Each point of the front moves with a velocity equal to the difference between the values (at this point) of the upstream flow velocity and of the normal burning velocity oriented toward the fresh mixture in the direction normal to the front.