Convegni ATI - Accesso riservato soci CTI

Autore: A. de Risi, T. Donateo, D. Laforgia

Collana: CA - 56 - Napoli 2001

Note:
The aim of the present investigation is to assess the influence of numerical parameters on the soot-NOx trade-off. Previous studies showed that some parameters used to calibrate both empirical and analytical models for numerical simulations strongly influence the predicted values of soot and NOx emissions. However, simulations codes are expected to match the engine emissions trend more than the effective measured values of soot and NOx for a particular operating condition. Thus, it is important to analyze the effect of these parameters on emissions levels for different values of injection starting, as fuel injection timing affect the performance and the emissions of a Diesel engine.
The investigated numerical parameters include variables related to spray, turbulence and combustion models. These variables are usually adjusted according to grid resolution, engine and injection system geometry as well as operating conditions. The effect of the time step chosen for the simulation has also been considered. The investigation has been carried out by using a modified version of KIVA3V code, which includes improved models for spray, turbulence, combustion process and emissions mechanisms of formation. The results of the numerical investigation have been compared with the measured soot-NOx trade-off of a commercial small bore direct injection diesel engine equipped with a common rail injection system.