Simulations of Fuel/Air Mixing, Combustion, and Pollutant Formation in a Direct Injection Gasoline Engine

2002-01-0835

03/04/2002

Event
SAE 2002 World Congress & Exhibition
Authors Abstract
Content
Simulations of a Direct Injection Spark Ignition (DISI) engine have been performed for both early injection with homogeneous charge combustion and for late injection with stratified charge combustion. The purpose has been to study flow characteristics, fuel/air mixing, combustion, and NOx and soot formation. Focus is put on the combustion modeling.
Two different full load cases with early injection are simulated, 2000 rpm and 6000 rpm. One load point with late injection is simulated, 2000 rpm and 2.8 bar net MEP. Three different injection timings are simulated at the low load point: 77, 82, and 87 CAD bTDC.
The spray simulations are tuned to match measured spray penetrations and droplet size distributions at both atmospheric and elevated pressure. Boundary conditions for the engine simulations are taken from 1-D gas exchange simulations that are tuned to match engine tests. The engine simulations start 380 CAD's before TDC and include the closing of the exhaust valves, the whole intake stroke, injection, combustion, and expansion to 113 CAD aTDC. Combustion is simulated using a turbulent Flame Speed Closure (FSC) model. The model takes into account the effects of local mixture composition, turbulence, temperature, and pressure and predicts reasonably well the heat release rate in all the cases without tuning of any constants. From this it is concluded that it is well suited for SI engine combustion predictions. The model also handles the diffusion controlled post oxidation of the unburned fuel from overly rich regions.
Meta TagsDetails
DOI
https://doi.org/10.4271/2002-01-0835
Pages
14
Citation
Wallesten, J., Lipatnikov, A., and Chomiak, J., "Simulations of Fuel/Air Mixing, Combustion, and Pollutant Formation in a Direct Injection Gasoline Engine," SAE Technical Paper 2002-01-0835, 2002, https://doi.org/10.4271/2002-01-0835.
Additional Details
Publisher
Published
Mar 4, 2002
Product Code
2002-01-0835
Content Type
Technical Paper
Language
English