Effect of Different Configurations on the Novel Multi-stage Acceleration Pre-chambers

In the present work, a series of two-dimensional (2D) numerical simulations are conducted to investigate the influence of various configurations on the performance of the novel multi-stage acceleration pre-chambers. A detailed mechanism of hydrogen is utilized to simulate the fuel properties. The effect of different parameters such as the orifice diameter and obstacle position is investigated in single-stage acceleration pre-chambers, two-stage acceleration pre-chambers, and three-stage acceleration pre-chambers. Both the orifice diameter and pre-chamber volume can significantly influence the performance of single-stage pre-chambers. However, the effect of the orifice diameter is moderated due to the larger flame surface generation in the two-stage pre-chamber which promotes the upcoming acceleration and offsets the influence of the lower flame tip velocity. Besides, the distribution of the obstacle is found to have a significant influence on the performance of two-stage acceleration pre-chambers. All two-stage acceleration pre-chambers have a better performance compared to the single-stage pre-chambers as the extra obstacle advances the flame acceleration and introduces turbulence in the pre-chamber. In three-stage acceleration pre-chambers, the flame tip velocities under different orifice diameters are more similar since the offset effect takes place one more time. However, it is also found that the length scale of the pre-chamber can influence the flame acceleration. As long as the distance between adjacent obstacles is large enough, the three-stage acceleration pre-chamber can also acquire a decent performance as the turbulent flame formation is not limited anymore.