Future stringent legislation on emissions from diesel engines means a great challenge to the engine manufacturers. The fundamental combustion processes in the diesel engine have historically been considered too complicated to model. However, recent developments of models in combination with the very rapid computer development now make calculations possible with a sufficient degree of accuracy.
In the project a model for the simulation of emissions from diesel engines will be developed. Effects caused by fuel injection rate shaping, heat transfer and by exhaust gas recirculation, EGR, will all be taken into account. The model will be carefully validated experimentally as well as numerically.
The emission model will be based on a special formulation of the flamelet model called Representative Interactive Flamelets, RIF. The RIF model requires as input time-resolved numerical data of scalar fields from a 3-D flow and combustion calculation, and is then able to calculate emissions of soot and NOx for the combustion cycle under study. Also emissions of unburned hydrocarbons and CO can be calculated. The flamelet calculations will employ a few hundred elementary chemical reactions.
The developed tool for emission calculations will be applicable to a wide range of engine operation conditions. First validation will be done in "simple" combustion systems, combustion cells. Further validation will be based on the results from well defined engine experiments, which will include variations of the injection pressure and injection rate shape. When a working combination of codes has been developed, participating car manufacturers will validate the combustion/emission simulation tool by comparing with experimental results using their own engines and operating conditions. Both car and truck size engines will be covered.
Expected Achievements and Exploitation
Future diesel engines will incorporate features like high pressure fuel injection, fuel injection rate shaping, multiple injection, advanced nozzle orifice design and possibly EGR. In the DIESEL project, a predictive method to calculate emissions from diesel engines will be developed taking most new engine features into account. The numerical tool will subsequently be used for pre-selection of new engine combustion concepts. Based on information from calculations, it should be possible to produce first engine prototypes with a design closer to that of the final engine, thereby reducing the number of necessary prototypes. The traditional experimental engine development procedure will not be abandoned in the foreseeable future, however, the development process has a potential to become more efficient if the number of prototypes and engine experiments can be reduced.
Funding SchemeCSC - Cost-sharing contracts
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