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T. Lauer, N. Bobicic, M. Heiß, W. Holly, S. Pritze:
"A Comprehensive Simulation Approach to Irregular Combustion";
Talk: SAE 2014 World Congress & Exhibition, Detroid, USA; 2014-04-08 - 2014-04-10; in: "SAE 2014 World Congress & Exhibition", http://www.sae.org/congress/2014/attend/program/, (2014), 16 pages.

The combustion of highly boosted gasoline engines is limited by
knocking combustion and pre-ignition. Therefore, a comprehensive modelling approach consisting of cycle-to-cycle simulation, reactor modelling with detailed chemistry and CFDsimulation was used to predict the knock initiation and to identify the source of pre-ignition. A 4-cylinder DISI test engine was set up and operated at low engine speeds and high boost pressures in
order to verify the accuracy of the numerical approach.
The investigations showed that there is a correlation between
the knocking combustion and the very first combustion phase.
The onset of knock was simulated with a stochastic reactor
model and detailed chemistry. In parallel, measurements with
an optical spark plug were carried out in order to identify the
location of knock onset. The simulation results were in good
agreement with the measurements.
Deposits and oil/fuel-droplets are possible triggers of preignition.
A multi-component fuel approach was therefore introduced to predict the wall film formation with the CFDsimulation.
Droplet-stripping from the wall film was evaluated.
The simulation of the chemistry of the oil/fuel droplets
confirmed the results from high-speed imaging that identified
droplets and deposits as a possible source of pre-ignition.

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