CFD-guided development of a pre-chamber ignition system for internal combustion engines

In the present paper, the development of a non-fuelled pre-chamber ignition system is introduced. 3D combustion CFD has been employed to guide the design change. Based on the combustion performance of different pre-chamber designs, one design (B4) is identified as the best one among several designs. Design B4 is selected for detailed evaluations. The results of Design B4 are compared with the baseline SI engine. The fuel economy has been improved by using the pre-chamber ignition system. However, NOx emission is higher than the baseline engine, due to higher in-cylinder pressure and temperature. The combustion process in the pre-chamber is separated into three steps characterised with its heat release, temperature and pressure. Based on the pressure difference between the main chamber and pre-chamber, a four-stage mechanism is proposed to describe the gas exchange between them.