Abstract
A mathematical model was developed for predicting the heat release rate in a 4-cycle medium speed diesel engine. In the model, it was emphasized to predict the fundamental processes occurring in the combustion chamber, which varied with time and space, from the microscopic point of view. The prediction was based on the knowledges concerning a single droplet as well as the droplet size distribution in a fuel spray and the spatial and temporal distribution of fuel in a combustion chamber. The heterogeneous field of temperature and equivalence ratio and uniform pressure were postulated. To describe the heterogeneity of spray combustion, the spray was divided into, a lot of small packages which experiences different histories of temperature, pressure and equivalence ratio. And the processes occurring in the packages were synthesized to predict the one in the entire spray. The prediction is consisted of the following topics: fuel injection simulation, spray formation, droplet size distribution, droplet evaporation, ignition delay and heat release. Sample calculation were made for 40cm bore and 48cm stroke supercharged marine diesel engine with different load.
