Large-Eddy Simulation and System simulation to predict Cyclic Combustion Variability in gasoline engines
A R&D project on piston engine combustion financed by the European Union in the frame of the 7th Framework Programme (FP7).
In a context of more and more stringent constraints on fuel consumption, CO2 emission, and pollutant emissions from road transport, it becomes crucial to be able to predict and control individual engine cycles, and thus to address the occurrence and effects of cyclic combustion variability (CCV). Piston engine technologies as direct injection (DI), controlled auto-ignition (CAI) or downsizing are key elements on the way to reducing the CO2 emissions from future SIE. Yet the occurrence, under certain operating conditions, of excessive CCV when implementing these technologies is one of the factors limiting their theoretical performance or range of operation. Being able to predict CCV in early design phases based on an improved knowledge of their sources and effects could be essential to exploit the full potential of these promising SI technologies under real operation.
The starting point for the present LESSCCV project was the fact that:
In this context, the overall objective of LESSCCV was to make use of the recent possibilities of advanced engine CFD tools to fundamentally improve the understanding of CCV related to the flow in SIE and provide adequate modelling. LESSCCV proposed developing innovative models to be combined with existing 1D-CFD SIE combustion chamber models to achieve a better reproduction of CCV and their impact on global engine behaviour. The aim was to base these new models on physical knowledge on the interaction between local and global flow effects, gained from the project's LES work.
The detailed scientific and technical objectives of work in LESSCCV were as follows: