Heating, Evaporation and Autoignition of Sprays

Abstract

Coupled solutions of the equations describing heating and evaporation of fuel droplets leading to autoignition of a fuel vapour/air mixture are described. A review of various approaches to the modelling of autoignition (in the presence or in the absence of droplets) is presented. Simplified models for coupling between droplet heating, evaporation and the autoignition of the fuel vapour/air mixture based on integral manifolds and positively invariant manifolds are described. This is followed by a description of the a numerical solution of the coupled system of Ordinary Differential Equations (ODEs), referring to droplet heating and evaporation, and the autoignition process, using the dynamic decomposition technique. As in the original integral manifold method, the formal approach to the decomposition of the system of ODEs is based on the division of system variables into ‘fast’ and ‘slow’. In contrast to the original version of the integral manifold method linearised variations of slow variables during the time evolution of the fast variables are considered as the first-order approximation to the fast manifold.