Numerical study of homogeneous pre-chamber design in an ethanol-fueled vehicular engine

Abstract

The use of pre-chamber ignition systems is a suitable alternative in the transition from internal combustion engines to fully electric solutions, since their use allows a reduction in specific fuel consumption and exhaust emissions. In this sense, the proper dimensioning of a pre-chamber influences significantly the flame propagation and, therefore, the combustion and performance characteristics. In this work, a commercial 4-cylinder engine equipped with a pre-chamber prototype was used to evaluate the influence of the pre-chamber internal volume, besides the diameter and arrangement of interconnection holes in the combustion development. For this, a CFD simulation was performed with the Converge Science software using the extended coherent flame model at stoichiometric condition. After validation with experimental data, modifications were carried out in the pre-chamber design, simulating six different configurations. Results indicated that the pre-chamber internal volume is the parameter that most influences on the combustion process. An increase in pre-chamber volume from 2.2 to 4.6% of the main combustion chamber could improve its capacity to release energy, reaching pressure peaks up to 3% higher when compared to a lower pre-chamber volume. It was also shown that a greater number of interconnection holes promote a more uniform jet distribution in the main chamber, while a smaller interconnection area could favor the kinetic energy and accelerate combustion.