Abstract
The effect of ozone on the combustion performance of methane-air mixture was studied with a constant volume combustion bomb test bench under different initial pressures and equivalence ratios. The laminar combustion characteristic parameters were obtained according to the flame propagation images. The comparison of the laminar combustion characteristic parameters showed that the O-atom decomposed from ozone can promote the reaction activity of the mixture. Based on the Markstein length, it can be concluded that ozone can increase the flame instability of the mixture, also the flame thickness decreased with ozone addition due to the acceleration of chemical reaction. Both the laminar flame speed and laminar burning velocity increased with ozone addition, and the maximum relative increment of the parameters all appeared at the equivalence ratio of 0.6, which showed the ozone had a more notable enhancement effect for lean methane-air mixture. It was feasible to enhance the combustion performance for natural gas engine using lean burn combustion in principle.
•Study the laminar combustion characteristic of ozonized methane/air mixture under lifted initial pressure.•Laminar combustion performance was improved due to the increase of active species with ozone addition.•Ozone addition reduced the flame thickness and increased the flame instability.•Ozone had a higher enhancement effect for the lean methane/air mixture.