An investigation on the behavior of the torch flame in the LBGE combustion process

Fuel conversion from heavy fuel oil (HFO) to LNG-based fuel, of which the main component is methane, is considered a suitable and practical solution. Most LBGEs adopt the pre-chamber (PC) configuration that can promote premixture combustion in the Main Combustion Chamber (MC) thanks to torch flame ejection from the orifice holes of the PC. However, the PC is sometimes specified as a starting point of the pre-ignition phenomenon that is a significant obstacle for Lean Burn Gas Engines (LBGEs) to improve their thermal efficiency. Too strong ejection may result in a misfire of the premixture MC and a considerable cyclic variation of the MC combustion. In this study, detailed observation of the combustion process was done in LBGE-simulating devices focusing on the ejection behaviors of the torch flame to clarify the source of the abnormal combustion and the cyclic variation of combustion processes.