Study on ignition mechanism of turbulent jet pre-chamber of H2/CO mixture

Abstract

Jet flow pre-chamber ignition is used to increase the thermal efficiency of lean-burn engines, but the ignition mechanism in the main chamber remains unclear. Therefore, the ignition mechanism of the jet pre-chamber was investigated experimentally and numerically. The results show that the flame in the pre-chamber can indeed propagate to the main chamber through a 2-mm-diameter nozzle without extinguishing. This occurs because at the very start the flame is located in the center of the nozzle and maintains a certain distance from the wall, preserving both temperature and free radicals. Next the flame in the nozzle will be extinguished due to fuel depletion, leading to a significant reduction in the concentration of free radicals. The free radicals pass through the nozzle, and compared with only the hot ignition, the ignition in the main chamber is one preparation period earlier, indicating a more concentrated heat release and higher thermal conversion ability in real engines.