Linköping University

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Physically Based Modelling for Knock Prediction in SI Engines

The high demand for an increase in performance and at the same time lowering the emissions is forcing the automotive industry to increase the efficiency of the vehicles. This demand lead to a problem called knock, which often is the limit- ing factor when increasing the efficiency of the engine. Knock occurs when the unburned gases inside the combustion chamber self-ignites due to the increasing pressure and temperature. This thesis investigates if it is possible to predict knock with a physically based knock model. The model consist of several sub-models such as pressure model, temperature model and knock model. The models are built by using mea- sured data and the goal is to get an independent knock prediction model that can find the limited ignition angle that will cause knock. The results shows that an analytic pressure model can simulate a measured pressure curve. But when it comes to predicting knock, there is an uncertainty which can be improved by changing the modelling strategy and making the mod- els more accurate.

Nils Thornberg and Jonas Kraft

2018

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Last updated: 2021-11-10