Based on a constant volume combustion chamber, the initial ambient pressure effect on gasoline combustion performance and flame propagation of the active and passive pre-chamber ignition systems were studied. Compared with the passive pre-chamber, the active pre-chamber can significantly expand the lean combustion limit from 1.2 to 1.5, enhance the ignition and combustion performance, and speed up the combustion of the main combustion chamber. At slightly lean combustion conditions, the heat release performance has a positive correlation with the initial ambient pressure. As the premixed λ increases, the heat release performance and the initial ambient pressure begin to become negatively correlated. Ignition delay can be decreased by approximately 50% at an initial pressure of 0.75 MPa, premixed lambda of 1.2 with APC compared with PPC. The high ambient pressure (1.0 MPa) in the constant volume chamber greatly reduces the mixture entrainment ability of the jet flame at lean combustion conditions, thereby reducing the combustion speed and peak heat release rate.

Based on a constant volume combustion chamber, the initial ambient pressure effect on combustion performance and flame propagation of the active and passive pre-chamber ignition systems were studied. Compared with the passive pre-chamber, the active pre-chamber can significantly expand the lean combustion limit, enhance the ignition and combustion performance, and speed up the combustion of the main combustion chamber. At slightly lean combustion conditions, the heat release performance has a positive correlation with the initial ambient pressure. As the premixed λ increases, the heat release performance and the initial ambient pressure begin to become negatively correlated. Ignition delay can be minimized by controlling the excess air coefficient in the pre-chamber close to the stoichiometric ratio. The high ambient pressure in the constant volume chamber greatly reduces the mixture entrainment ability of the jet flame at lean combustion conditions, thereby reducing the combustion speed and peak heat release rate.

The sparked-spray method represents a novel combustion approach that employs an electrical spark to directly ignite fuel spray through cooperative control of fuel injection and spark ignition timing, forming an intense flame kernel for enhanced combustion performance. This method offers potential advantages in combustion efficiency and flame propagation characteristics compared to conventional ignition strategies. This paper investigated the effects of ignition delay and fuel injection duration on sparked-spray combustion characteristics using gasoline and methanol as test fuels in an atmospheric environment through high-speed photography. The study systematically examined the relationship between ignition timing parameters and combustion performance by analyzing projected flame area as a quantitative measure of flame intensity. Experimental results demonstrate that optimal ignition occurs when the ignition delay is 1.2 ms or 1.5 ms, where the spray is more readily ignited and produces larger projected flame areas under identical injection duration conditions. Furthermore, regardless of injection duration variations, methanol spray consistently exhibits superior combustion characteristics, generating larger projected flame areas and longer flame survival duration compared to gasoline spray.