A Theoretical Study of Ignition in the Laminar Mixing Layer

The structure of the weakly reactive states leading to ignition in the laminar mixing layer flow is studied both analytically and numerically. It is shown that the flow consists of a reactive region and a self-similar frozen region separated by a transitional, nonsimilar frozen region, that the reactive region is intrinsically nonsimilar because of its excessively slow diffusion rate, and that the ignition characteristics are primarily governed by the velocity of the hot stream and therefore minimally dependent on the velocity distribution. Fundamental functional groups are identified, and an explicit prescription is presented, for large activation energy reactions, for the evaluation of the minimum streamwise distance to achieved ignition.