A phenomenological combustion model for direct-injection, compression-ignition engines

Abstract

This paper describes the development and use of a phenomenological model for combustion in direct-injection diesel engines. The model is based on the analysis of the fuel evolution from the injection start till the combustion end. The fuel evolution is modelled by studying the spray atomization, penetration, air entrainment, and evaporation; the air motion; the ignition delay; and the combustion. The model consists of analytical and semiempirical submodels for each of the above-mentioned phenomena, with a special emphasis on the spray behaviour during the atomization process and after the impingement against the walls. The model gives the amounts of fuel atomized, vaporized, and burned, and the amounts of air entrained and burned. The heat released by fuel combustion is used to compute the pressure evolution in the combustion chamber. An application of the model is made for a real engine, and a comparison between experimental and calculated pressure diagrams is presented, showing a good agreement.