Modelling Medium Speed Diesel Engine Combustion, Soot and NOx-emission Formations 2000-01-1886
The purpose of the present study was to model combustion, soot and NOx-emissions of a medium speed diesel engine using the modified KIVA-2 code.
Assesment of the droplet vaporization, the soot formation and its oxidation models were also done regarding the medium speed diesel engine.
Heavy fuel spray was modeled with the standard KIVA-2 chi-squared model including drag modification during droplet vaporization (the droplet distribution model), droplet vaporization with the high pressure Spalding and Abramzon&Sirignano models, combustion with the Magnussen EDC-model including a two step reaction mechanism, NOx formation with the extended Zeldovich model, soot formation with the modified Tesner&Magnussen model and soot oxidation with the EDC-model and Nagle and Strickland-Constable model (NSC). The RNG k-epsilon turbulence model was also implemented into the code. The Redlich-Kwong real gas equation of state and the formulation of Peng-Robinson fugacity coefficient equation were used.
The predicted cylinder pressures and heat-release rates in different cases were compared to that measured. Predicted NOx and soot values were compared with typical corresponding medium speed diesel engine values, this was due to the non-availability of NOx and soot measured values. In certain cases the predicted cylinder pressures and heat-release rates are quite well in agreement with those measured. The NOx and soot results are reasonable and behaved correctly. The developed engine CFD-modelling tool is at such a level now that it can aid the design of medium speed diesel engines.