Large-Scale CFD Approach for Spray Combustion Modelling in Compression-Ignited Engines

Computational simulations of the spray combustion and emissions formation processes in a heavy-duty DI diesel engine and in a small-bore DI diesel engine with a complicated injection schedule were performed by using the modified KIVA3V, rel. 2 code. Some initial parameter sets varying engine operating conditions, such as injection pressure, injector nozzle diameter, EGR load, were examined in order to evaluate their effects on the engine performance. Full-scale combustion chamber representations on 360-deg, Cartesian and polar, multiblock meshes with a different number of sprays have been used in the modelling unlike the conventional approach based on polar sector meshes covering the region around one fuel spray. The spray combustion phenomena were simulated using the detailed chemical mechanism for diesel fuel surrogate (69 species and 306 reactions). The simulations have been performed for Isotta Fraschini (DI diesel, 7 sprays) and Volvo NED5 (DI diesel, 10 sprays) engines, which are currently under development. Numerical results were predicted in agreement with typical experimental trends for such engines.