Numerical modelling of diesel spray auto-ignition and combustion

Abstract

This work presents the development and implementation of a spray combustion model based on the spray size distribution moments approach to spray modelling. The governing equations for both the gas and liquid phases are solved by the finite volume method based on an Eulerian framework. The model used in the auto-ignition and combustion analysis is a combination of the probability density function and eddy break-up approaches. This scheme is developed in order to effectively validate both ignition and combustion phases. It is designed to compromise between the chemical reaction rate when dealing with the auto-ignition mode, and the turbulence reaction rate which dominates the combustion mode using a reaction progress variable which represents the reaction level. These average reaction rate source terms in transport equations for species are evaluated by a probability density function averaging approach. The developed ignition and combustion model is shown to have significant potential as a numerical tool for predicting the phenomena involved in spray combustion in diesel engines.