基于不同喷嘴旋角气流协同作用的主动预燃室射流火焰研究

This paper aims to study active pre-chamber(APC)jet flame formation based on the synergy of airflow with different nozzle swirl angles.A single-cylinder gasoline direct injection Atkinson cycle engine with a compression ratio of 17 was used to operate the ultra-lean(λ=2.5)conditions.Different APC structures with nozzle swirl angles ranging from 0° to 30° were designed to produce different flow fields inside APC.The result showed that the change of nozzle swirl angle not only affects the state of fuel-air mixture in the center of spark plug electrode but also affects the overall mixture distribution inside APC.APC with larger nozzle swirl angle has less wall film and faster fuel-air mixing to form a more evenly mixture distribution in APC top region,which improve the uniformity of the flame jets from different APC nozzles with a smaller Variance of jet TKE and jet velocity.Tumble flow plays a dominant role in the APC with a small nozzle swirl angle and the relatively weak swirl flow field inside APC results in more locally rich mixture regions that reduce the ignition capability of jet flame.