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Talks and Poster Presentations (with Proceedings-Entry):

W. Holly, M. Heiß, N. Bobicic, T. Lauer, S. Pritze:
"Investigation on Knocking Combustion with Reaction Kinetics for a Turbocharged SIDI Engine";
Talk: Klopfen Irreguläre Verbrennung, Berlin; 2013-12-09 - 2013-12-10; in: "Knocking in Gasoline Engines", M. Kratzsch, M. Günther (ed.); (2013), 17 pages.



English abstract:
For highly boosted gasoline engines with direct injection (DI) the high-load operating conditions with lowest fuel consumption are restricted by irregular combustion like knocking. Therefore, the analysis of the initiation mechanism for knocking was the subject of this research work.
Cylinder pressures and burn rates were measured at the knock limit for a turbocharged DI test engine. A 1D multi-cycle three-pressure-analysis was applied to investigate the cycle-to-cycle variations. The results showed that important mean charge properties such as the charge mass or the composition were within a narrow range after inlet valve closing. Furthermore, it could be shown that the duration until 2 % mass fraction burned is a clear indicator if autoignition occurs for a given cycle. All cycles with an accelerated early flame development showed an irregular heat release during the combustion phase. A CFD-simulation was carried out in order to study the mixture properties and turbulence close to the spark plug.
The self-ignition of the unburned mixture was simulated with a stochastic reactor model. The mixture properties were modelled with probability density functions. A toluene reference fuel was used to describe the chemistry of gasoline with a detailed chemical mechanism. With this approach, the onset of the timing was calculated in good agreement with the measurements. The formation of typical intermediate species during the autoignition could be identified. A critical mass fraction of HO2 in the range of 10-4 was derived for the knocking cycles.

Created from the Publication Database of the Vienna University of Technology.