Conditional moment closure modeling of turbulent spray combustion in a direct injection diesel engine

Abstract

Combustion of turbulent sprays in a direct injection diesel engine is modeled by the conditional moment closure (CMC) model. The CMC routines are combined with the KIVA code to provide conditional flame structures to determine mean state variables, instead of mean reaction rates. An independent transport equation is solved for each flame group with equal mass of sequentially evaporating fuel vapor. CMC calculation begins as the fuel mass for each flame group begins to evaporate with corresponding initialization conditions. Comparison is made with measured pressure traces for four operating conditions at different rpm's and injection conditions. Results show that the CMC model with multiple flame histories can successfully be applied to ignition and mixing-controlled combustion phases of a diesel engine.