A Numerical Study of the Influence of Different Operating Conditions on the Combustion Development in an Automotive-Size Diesel Engine 2015-01-1852
In this paper, numerical simulations of an automotive-size optical diesel engine have been conducted employing the Reynolds-Averaged Navier-Stokes (RANS) equations with the standard k-ε turbulence model and a reduced n-heptane chemical mechanism implemented in OpenFOAM. The current paper builds on a previous work where the model has been validated for the same engine using optical diagnostic data. The present study investigates numerically the influence of different operating conditions - relevant for modern diesel engines - on the mixture formation development under non-reactive conditions as well as low- and high-temperature ignition behaviour and flame evolution in the presence of strong jet-wall interactions typically encountered in automotive-size diesel engines. Also, emissions of CO and unburned hydrocarbons (UHC) are considered. This has been systematically studied by varying four different engine parameters: 1) Engine swirl: zero, nominal (baseline) and double of the swirl; 2) Fuel injection pressure: 1000 and 1600 (baseline) bar; 3) Intake pressure: 1 (baseline) and 2 bar; 4) Ambient oxygen mole fraction: 21 (baseline) and 15%.
The swirl was found to have a minor influence on the inert fuel spatial distribution. On the other hand, the swirl has a large impact on the high-temperature rather than on the low-temperature ignition and this effect is more pronounced for the low fuel injection pressure case where high-temperature combustion on the up-swirl side is suppressed for the high swirl case. This effect is not observed for the 1600 bar injection pressure case and it can potentially have a strong impact on the unburned hydrocarbons (UHC) emissions.
Citation: Pasunurthi, S., Hawkes, E., Bolla, M., Le, M. et al., "A Numerical Study of the Influence of Different Operating Conditions on the Combustion Development in an Automotive-Size Diesel Engine," SAE Technical Paper 2015-01-1852, 2015, https://doi.org/10.4271/2015-01-1852. Download Citation
Shyam S. Pasunurthi, Evatt R. Hawkes, Michele Bolla, Minh K. Le, Sanghoon Kook, Tommaso Lucchini, Gianluca D'Errico
University of New South Wales, Dipartimento di Energia, Politecnico di Milano
JSAE/SAE 2015 International Powertrains, Fuels & Lubricants Meeting