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Controlling abnormal auto-ignition processes in spark-ignition engines requires understanding how auto-ignition is triggered and how it propagates inside the combustion chamber. The original Zeldovich theory regarding auto-ignition propagation was further developed by Bradley and coworkers, who highlighted different modes by considering various hot spot characteristics and thermodynamic conditions around them. Dimensionless parameters (ε, ξ) were then proposed to classify these modes and to define a detonation peninsula for H2-CO-air mixtures. This article deals with numerical simulations undertaken to check the relevancy of this original detonation peninsula when considering realistic gasoline fuels. 1D calculations of auto-ignition propagation are performed using the Tabulated Kinetics for Ignition model.

This study presents a preliminary application of Large-Eddy Simulations (LES) of a speed transient performed on a motored single-cylinder engine. The numerical setup follows a methodology which has been validated and optimized for stabilized operating points in previous work, and adapted to run a speed transient of 31 cycles, from 1000 to 1800 rpm. Analysis of the results contributes to characterize the impact of the transient on the engine charge, tumble motion and velocity distribution. These simulations, which have never been performed in the past (to the best of our knowledge), represent a decisive step towards modeling and understanding transient in GDI engines, and particularly their impact on soot particle emissions in real driving conditions.