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Contact

Institute for Powertrains and Automotive Technology
Vienna University of Technology 
Getreidemarkt 9
1060 Vienna, Austria
Phone: +43 1 58801 31500
Mail: info[at]ifa.tuwien.ac.at

Office opening hours:
Mo-Fr: 8 am - 4 pm

Combustion models

Modern numerical methods are used at the Institute for Powertrains and Automotive Technology to describe the combustion process of internal combustion engines. Depending on the targets, different approaches with different modelling depth of the physical and chemical processes are used.

Zero dimensional models for example use empirical and phenomenological approaches and therefore leads to low numerical effort. As a consequence, these models are suited to simulate a high number of different cases. Therefore they are used in combination with optimization software to find operating points with highest efficiencies and low emissions.

To investigate the spatial flame propagation in the cylinder, three dimensional combustion models based on the flame surface density are used. These models are able to describe premixed and none premixed flames. Furthermore it is possible to study the interaction between the in-cylinder flow, mixture formation and chamber geometry to improve the combustion process.
Figure 1: Distribution of the flame surface density and mean flame front of a typical SI-engine at 50 % MFB
Figure 1: Distribution of the flame surface density and mean flame front of a typical SI-engine at 50 % MFB
Since the efficiency of spark ignition engine is limited by irregular combustion like knocking combustion and pre-ignition, some research work is carried out at the institute to model these phenomena. It shows, that detailed reaction kinetics are a powerful tool to model the selfignition of the cylinder charge. To achieve low computational effort, stochastic reactor model are used which describes the inhomogeneities in the cylinder with probability density functions. This simulation methodology is able to describe the selfignition timing of individual knocking cycles with good agreement to the test bench data (Fig. 2).
Figure 2: Validation of the simulated pressure and heat release rate of a knocking cycle
Figure 2: Validation of the simulated pressure and heat release rate of a knocking cycle

Contact:
Dipl.-Ing. Werner Holly BSc
Phone: +43 1 58801 31528
Mail: werner.holly[at]ifa.tuwien.ac.at

Publications:

[1] Lauer, T.; Heiss, M.; Bobicic, N.; Pritze, S.: Modellansätze zur Entstehung von Vorentflammungen. Motortechnische Zeitschrift MTZ 01/2014

[2] Holly, W.; Heiss, M.; Bobicic, N.; Lauer, T.; Pritze, S.: "Investigation on Knocking Combustion with Reaction Kinetics for a Turbocharged SIDI Engine", 4th International Conference on Knocking in Gasoline Engines, Berlin, 2013

[3] Heiss, M.; Bobicic, N.; Lauer, T.; Geringer, B.; Schmuck-Soldan, S.: "A Detailed Analysis of the Initiation of Abnormal Combustion with Reaction Kinetics and Multi-cycle Simulation”, In: Proceedings of the FISITA 2012 World Automotive Congress (2013), Vol. 190, pp. 1007-1018

[4] Forsthuber, F.; Krenek, T.; Marinitsch, F.; Lauer, T.; Raup, M.; Schatzberger, T.; Weiß, J.: Investigations on the Tail-Pipe Emissions of Commercial Engines with Advanced One-Dimensional Simulation Methods. SAE Technical Paper 2013-01-1117

[5] Lauer, T.; Pizzirani, N.; Murakami, S.: Computational study on the combustion concept of a lean burn gas engine. 10. Tagung Motorische Verbrennung, München, 2011