Reducing the cycle variability in a spark ignition simulated engine

Abstract

The present work aims to study the optimal parameter configuration for different operating and design variables of a spark ignition engine with the goal of minimizing the cyclic variability (CV) of its efficiency time series. We make use of a quasi-dimensional numerical simulation of a mono-cylindrical spark ignition engine. The CV is modelled by incorporating a stochastic component in the characteristic length and the velocity of the turbulent combustion model. The focus of this work is to reduce CV through the reduction of the coefficient of variation, considering five different parameters, related to the crankshaft angle, that have incidence in CV: the spark advance, the intake valve opening angle, the intake valve closing angle, the exhaust valve opening angle, and the exhaust valve closing angle. A Random Search method was used for sampling the search space of the different parameters, considering a discretization angle of one degree. The results show that a significant reduction in the coefficient of variation can be obtained by appropriately choosing the parameter values for the different operating scenarios of the spark ignition engine. The experimental evaluation also shows that the two most relevant parameters with a greater incidence in reducing the coefficient of variation are the spark advance and the intake opening valve angle.