Mixture formation and combustion of biofuels in diesel engine

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The latest generation of diesel engines allow with its common-rail injection system a great flexibility in injection timing as well as offering the opportunity of using multiple injection strategies. Furthermore, biofuel or renewable fuels offer the possibility to reduce greenhouse gas emissions when the fuel life-cycle is considered. In this research program, it is proposed to study the impact of multiple injection strategy in combination to different biofuels as to evaluate the true potential of these fuels as well as identifying the impact of fuel properties on injection strategies, for example. Thus experiments will be conducted with a diesel engine. To gain an understanding of the phenomena at play and to help explaining the observed behavior in engine, experiments in a pressurized vessel as well as Large Eddy Simulations (LES) will be pursued. The experiments in the pressurized vessel will allow isolating different influencing parameters and to see their impacts on the mixture formation process through advanced optical diagnostics. These latter results will help develop advanced tools for engine design such as a correlation for predicting fuel spray tip penetration for multiple injection and based on the initial fuel spray momentum. LES in combination to the implementation of improved atomization model and multispecies evaporation model will allow studying the physical phenomena at play during the mixture formation process and will thus offer a rational explanation for the observed results in engine as a function of fuel properties and injection strategy.