On Autoignition of Co-Flow Laminar Jets

Abstract

This paper is concerned with the derivation and mathematical analysis of a model for autoignition of laminar co-flow jets. Such jets consist of two parts: an inner part with oxidizer that is surrounded by an outer part with fuel, or the reverse. To derive a model we use a combination of Burke--Schumann theory of diffusion flames and Semenov--Frank-Kamenerskii theory of thermal explosion. The main advantage of our model is that it gives a well-defined condition for autoignition of a jet. We provide detailed analysis of the model that reveals dependency of the autoignition position on principal physical and geometric parameters involved. Moreover, we give explicit expressions for autoignition position in asymptotic regimes relevant to applications.