This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Knock Tendency Prediction in Highly Charged SI Engines
Published November 05, 2017 by Society of Automotive Engineers of Japan in Japan
Annotation ability available
The continually increasing stringent requirements in terms of emissions and performance lead to the demand for further development of gasoline engines, in order to satisfy the regulations and to be competitive in the market.
One of the main limitations in simultaneously improving the efficiency and performance of SI engines is the knock behaviour. This phenomenon limits either the possibility to adopt a higher compression ratio, which would be beneficial for the engine efficiency, or it causes a poor combustion timing which leads to a higher fuel consumption and a lag in performance. As a result, having the possibility to judge the risk of knock during the design phase can be beneficial to increase the potentials of the engine.
In this work, a methodology for the prediction of the knock tendency in spark ignition engines using a 3D-CFD software has been developed. This method, evaluating the local conditions in the combustion chamber, allows to predict also the area where the autoignition will occur. For this study, two approaches, based on the work of Douaud & Eyzat  and the Kinetics-fit model , have been considered and compared.
Both approaches were evaluated at low-end torque and peak power, which represent the most significant points to describe the performance of an engine at full load, showing a good accordance with the theory behind the knock.
In conclusion, a comparison between the results in the two operating points has been performed, obtaining an objective criterion, independent of the engine operating conditions, for the prediction of the knock tendency.
CitationBevilacqua, V., Boeger, M., Corvaglia, G., Penzel, M. et al., "Knock Tendency Prediction in Highly Charged SI Engines," SAE Technical Paper 2017-32-0130, 2017.
- Deutsches Zentrum für Luft- und Raumfahrt, Wuppertal Institut für Klima, Umwelt, Energie GmbH Begleitforschung zu Technologien, Perspektiven und Ökobilanzen der Elektromobilität - STROMbegleitung März 2015
- The International Council on Clean Transportation CO 2 emissions from new passenger cars in the EU: Car manufacturers’ performance in 2014 ICCT Policy Update July 2015
- Douaud , A. M. and Eyzat , P. Four-Octane-Number Method for Predicting the Anti-Knock Behavior of Fuels and Engines SAE 780080 , SAE Transactions, v87 1978
- Livengood , J. and Wu , P. Correlation of Autoignition Phenomenon in Internal Combustion Engines and Rapid Compression Machines 1955
- Gamma Technologies GT-Power Manual 2016
- Heywood J. B. Internal combustion engine fundamentals McGraw-Hill New York 1988
- Ra , Y. and Reitz , R. D. A combustion model for IC engine combustion simulations with multi-component fuels Combustion and Flame 69 90 2011