Abstract
Mega-knock in super-charged gasoline engines is predicted to occur at locations in the compressed charge where the turbulence level is relatively low and therefore a local detonation may develop. Such situations can substantially be reduced by a suitable design of the geometry of the combustion chamber. CFD simulations based on the k--turbulence model can predict the location where the detonation is most likely to develop and its probability to occur. Thereby, even for existing engines mega-knock can be avoided by choosing appropriate operating conditions, where the maximum detonation probability is very low. This paper presents a methodology which predicts the detonation probability in terms of local thermodynamic and turbulent flow parameters. This allows to calculate, for a given engine geometry, response surfaces in terms of operation parameters which could then be used for model predictive control.
KEYWORDS – mega-knock, pre-ignition, turbulence, detonation probability, model predictive control