高能点火对电弧发展和稀燃影响的可视化研究

Visualization for Influence of High Energy Ignition on Electric Arc Development and Lean Combustion

基于光学单缸机和高速摄影,结合点火系统的放电特性,研究了放电电弧的形成和发展受进气流场和点火能量的影响以及高能点火对稀薄燃烧的影响。结果表明:常规点火系统放电持续时间约2.6 ms,初始功率约30 W,且功率随时间迅速衰减,点火能量仅40 mJ。相比常规点火,高能点火系统通过大电流和长时间的设计,16 V供电下放电持续4.3 ms,初始功率达120 W,点火能量达254 mJ。在144 mJ点火能量下,随着进气压力从35 kPa逐渐增至101 kPa,电弧被吹断的概率从14%增至73%。在66 kPa进气压力下,随着点火能量从144 mJ增加到254 mJ,电弧被吹断的概率从39%降至5%。提高点火能量可以提高燃烧稳定性,缩短燃烧持续期,稀燃极限过量空气系数从1.7增加到1.82。

Combined with the discharge characteristics of ignition system,the influence of intake flow field and ignition energy on formation and development of electric arc and the influence of high energy ignition on lean combustion were studied based on the optical single-cylinder engine and high-speed photography.The results showed that the conventional discharge duration of ignition system was about 2.6 ms,the initial discharge power was about 30 W and dropped rapidly with time,and the ignition energy was only 40 mJ.Compared with the conventional ignition,the high energy ignition system has the large current and long duration design.With the power supply of 16 V,the discharge duration was 4.3 ms,the initial discharge power was 120 W,and the ignition energy reached 254 mJ.The probability of electric arc being blown off increased from 14%to 73%at the ignition energy of 144 mJ when the intake pressure increased from 35 kPa to 101 kPa,and the probability decreased from 39%to 5%at the intake pressure of 66 kPa when the ignition energy increased from 144 mJ to 254 mJ.In addition,increasing ignition energy could improve combustion stability and shorten combustion duration,and the lean limit of excess air coefficient also increased from 1.7 to 1.82.