Lean-Burn Ignition Characteristics of Methane/Air Premixed Jet

Abstract:

The effects of jet equivalence ratio， jet velocity， and co-flow velocity on the ignition characteristics of methane/air premixed jet were investigated on a controllable thermal-atmosphere combustion experimental system. According to the experimental law， the optimization suggestions for the lean-burn control strategy of natural gas engines were proposed to reduce the occurrence of the misfire. The results show that the lean limit of methane/air premixed jet decreases and the rich limit increases as co-flow temperature rises， which is consistent with the distribution of ignition limits of most hydrocarbon fuel premixes. Besides， there are different critical equivalence ratios at different jet velocities and co-flow velocities， below which the ignition temperature decreases sharply with the increase of jet equivalence ratio. Moreover， at a lower jet equivalence ratio （0.20~0.62）， the improvement in jet velocity can reduce the ignition temperature and optimize the ignition characteristics.