A constant equivalence ratio multi-zone approach for a detailed and fast prediction of performances and emissions in CI engines
2022-01-0455
03/29/2022
- Event
- Content
- The paper illustrates and validates a novel predictive combustion model for the estimation of in-cylinder performances and pollutant production in CI engines. The numerical methodology was developed by the authors for near real-time and / or control-oriented applications, while aiming at an accurate description of the air mixing process by means of a multi-zone approach of the air-fuel mass. Charge stratification is estimated via a 2D representation of the fuel spray distribution that is numerically derived by an axial one-dimensional control-volume description of the direct injection. The radial coordinate of each control volume is reconstructed a posteriori by means of a local distribution function. Fuel mass clustered in each zone is further split in ‘liquid’, ‘unburnt’ and ‘burnt’ sub-zones, given the local properties of the fuel spray control volumes with respect to space-time location of modelled ignition delay, liquid length, and flame lift-off. Multiple injections are described on the same numerical grid to account for jet-to-jet axial interactions, whose effects reflect on improved ignition characteristics. The multi-zones are open systems which are discretized on the equivalence ratio; mass is allowed to travel from one another causing a 2D charge stratification. For each multi-zone, local thermodynamic properties and NOx production are determined to estimate cylinder-average performances and emissions. The charge stratification sub-model is validated against CFD data, and peak cylinder pressure, BSFC and NOx emissions are validated against CFD and experimental data of full map of a heavy-duty engine. The computational effort of the model is relatively low, which makes the approach suitable for control-oriented applications, optimization of long transients, and simulation of driving cycles.
- Citation
- Tamborski, M., D'Errico, G., Lucchini, T., Cerri, T. et al., "A constant equivalence ratio multi-zone approach for a detailed and fast prediction of performances and emissions in CI engines," SAE Technical Paper 2022-01-0455, 2022, .