Numerical Analysis of the Performance of an Engine with a Pre-Chamber Equipped with an Air Injector Operating in TJI Mode

The sustainability of the transportation sector demands the continuous development of new technologies in internal combustion engines, aiming at reducing pollutant and greenhouse gas emissions while increasing fuel conversion efficiency. Pre-chamber (PC) ignition systems have recently emerged as an important technological pathway to explore. These systems generate turbulent combustion gas jets capable of accelerating flame propagation in the main chamber. The use of this mechanism enables a more homogeneous and efficient combustion, as well as allowing an increase in the compression ratio, resulting in improvements in engine performance and a reduction in pollutant emissions. One of the strategies to further enhance the benefits of pre-chambers is the introduction of air injectors. The objective of this modification is to promote the cleaning of residual gases that remain in the pre-chamber after combustion, mitigating adverse effects such as mixture dilution and ignition instabilities, in addition to favoring more complete combustion. In this context, the present study presents a numerical analysis of the performance and emissions of a single-cylinder research engine operating in turbulent jet ignition (TJI) mode with a pre-chamber equipped with air injectors. Simulations were performed using CONVERGE CFD software to evaluate the baseline pre-chamber configuration and three variations with conical air injectors featuring orifices of 2 mm, 1 mm, and 0.5 mm connected to the pre-chamber. The results showed that the 1 mm orifice configuration exhibited the best performance compared to the baseline configuration and other variations, delivering higher combustion efficiency and indicating superior residual gas cleaning.