Experimental study on premixed combustion characteristics of methane-air under dual spark plug ignition strategy in a closed spherical chamber

Dual spark plug ignition technology can effectively improve the low heat release rate of engine caused by slow combustion of natural gas. However, the mechanism of flame stability and ion current in the combustion process of double flame are not clear. This study is based on a nearly spherical closed constant volume combustion chamber experimental platform. Experiments on premixed combustion characteristics of methane-air under different ignition strategies (single spark plug ignition, dual spark plug synchronous ignition and asynchronous ignition) were carried out. The cellular structure of flame front and the relationship between the stretch flame propagation velocity and stretch rate were analyzed. The effects of different ignition strategies on heat release rate and ion current signal were analyzed. The results show that the flame stability of single spark ignition and synchronous ignition is better than that of asynchronous ignition. Under the asynchronous ignition strategy, the flame front appears fold and cellular structure with the increase of ignition interval time. Markstein length is the smallest and flame stability is the weakest due to the action of opposite flame. The heat release rate and mean ion current of synchronous ignition are higher than those of single spark plug ignition, and are not different from those of asynchronous ignition. Dual spark ignition greatly shortens the main combustion duration and is conducive to rapid combustion. Synchronous ignition is a promising ignition strategy which can guarantee flame stability and increase combustion velocity.

Automated summary

Dual spark plug ignition technology improves the low heat release rate of natural gas engines. This study investigated the flame stability and ion current mechanism of double flame combustion. The results showed that synchronous ignition leads to better flame stability and higher combustion velocity, making it a promising ignition strategy.