Heating, Evaporation and Autoignition of Sprays

Abstract

Possible approaches to coupled solutions of the equations describing heating and evaporation of fuel droplets leading to autoignition of a fuel vapour/air mixture are discussed. Firstly, the focus is on a brief overview of various approaches to the modelling of autoignition (in the presence or in the absence of droplets). Then a simplified model for coupling between droplet heating, evaporation, and the autoignition of the fuel vapour/air mixture, based on the integral manifold method, is presented and discussed. This is followed by a description of the approach to the numerical solution of the coupled system of ordinary differential equations (ODEs) describing droplet heating and evaporation and the autoignition process based on the dynamic decomposition technique. As in the original integral manifold method, the formal approach to decomposition of the system of ODEs in the latter method is based on the division of system variables into ‘fast’ and ‘slow’. In contrast to the original version of the integral manifold method, however, linearised variations of slow variables during the time evolution of the fast variables are taken into account as a first-order approximation to the fast manifold.