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Development of SI engines to further increase engine efficiency is strongly affected by the occurrence of engine knock. Engine knock has been widely investigated over the years and the main promoting parameters have been identified as load (temperature and pressure), mixture composition, engine speed, characteristic of the fuel, combustion chamber design, and etc. In this paper a new model for predicting engine knock in 0-D environment is presented. The model is based on the well-known approach of using a Livengood and Wu knock integral. Ignition delay data that are supplied to the knock integral are for specific fuel calculated by detail chemical kinetics and are comprised of low temperature heat release ignition delay and high temperature heat release ignition delay. Next, the cycle to cycle variations of engine and temperature stratification of the end gas have to be taken into account.

As a contribution to the research into HCCI engines which have a potential of achieving low fuel consumption with low particulate and low NOx emissions, a six zone simulation model coupled with the cycle simulation code AVL Boost was previously developed. The model uses comprehensive chemical kinetics and shows good agreement with experimental results. At the point of transition from the gas exchange process to the high pressure cycle, which is multi-zonal, the model assumes equal gas mixtures in all zones. Therefore, the model is suitable for perfectly homogeneous mixtures, and since it has no ability to receive fuel during compression, the mixture has to be prepared outside the cylinder. Further development of this model, which will be shown in this paper, includes the introduction of initial conditions with non-uniform mixtures and the possibility of receiving fuel during compression.

A promising strategy for increasing thermal efficiency and decreasing emissions of a spark ignited (SI) internal combustion engine is the application of lean mixtures. The flammability limit of lean mixtures can be increased by using an active pre-chamber containing an injector and a spark plug, resulting in a combustion mode commonly called Turbulent Jet Ignition (TJI). The optimization of the combustion chamber shape and operating parameters for TJI combustion can be a demanding task, since the number of design parameters is significantly increased and is today supported by numerical simulations. In this paper, the process of the development of a numerical framework based on 3D CFD and 1D/0D numerical models that will support the research of the pre-chamber design and optimization of operating parameters will be shown. For 3D CFD modelling the AVL Fire™ code is employed, where the full combustion chamber model with intake and exhaust ports of the experimental engine is prepared.