Comparative tests and analysis of ignition energy and ionic state in lean combustion

Abstract

The reliable ignition of air mixture is one of the main difficulties in lean combustion. It is generally believed that the improvement on the ignition system lies in enhancing the ignition energy; this paper, on the other hand, reveals, by conducting comparative tests of ignition energy and ionic state when the ignition system works under normal combustion and when the system works under lean combustion, that the energy emitted in such three stages as puncture, electric arc and emitting light of the same ignition system does not show obvious fluctuation under different air mixture conditions. In other words, different air-fuel ratios do not exert great impact on the performance of the ignition system; the increase of ignition energy alone cannot guarantee the rise in ignition reliability in lean combustion. Further analysis demonstrates that in the three stages of electrode ignition, the puncture stage, which accounts for only a small portion of the total energy, has the highest energy conversion rate. Extending the puncture time or accomplishing repeated punctures proves to be an effective way to boost ignition reliability in lean combustion.