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This work presents the study of the methane jet flame in a pressurized vitiated co-flow burner (PVCB). The lift-off length and the stabilization of the methane jet flame under different environment pressures, co-flow temperatures, co-flow rates and jet velocities have been studied, and a chemical numerical simulation based on Gri-mech 3.0 was analyzed as well. The results could provide theoretical supports for the research of natural gas engine combustion stabilization control to increase its thermal efficiency. The experimental results show that the lift-off length decreases obviously (104.22mm to76.14mm) with the increase of the environment pressure (1to1.5bar, 1073K) and temperature (119.34mm to 43.74mm from 1058K to 1118K, 1bar), meanwhile, it also increases with the increment of the co-flow rate and jet velocity.

Gasoline Direct Injection (GDI) engines have attracted interest as automotive power-plants because of their potential advantages in down-sizing, fuel efficiency and in emissions reduction. However, GDI engines suffer from elevated unburned hydrocarbon (HC) emissions during start up process, which are sometimes worsened by misfires and partial burns. Moreover, as the engine is cranked to idle speed quickly in HEVs (Hybrid Electric Vehicle), the transients of quick starts are more dramatically than that in traditional vehicle, which challenge the optimization of combustion and emissions. In this study, test bench had been set up to investigate the GDI engine performances for ISG (Integrated Starter and Generator) HEVs during start up process. Based on the test system, cycle-controlled of the fuel injection mass, fuel injection timing and ignition timing can be obtained, as well as the cycle-resolved measurement of the HC concentrations and NO emissions.

This paper presents a study of LPG lean burn in a motorcycle SI engine. The lean burn limits are compared by several ways. The relations of lean burn limit with the parameters, such as engine speed, compression ratio and advanced spark ignition etc. are tested. The experimental results show that larger throttle opening, lower engine speed, earlier spark ignition timing, larger electrode gap and higher compression ratio will extend the lean burn limit of LPG. The emission of a LPG engine, especially on NOx emission, can be significantly reduced by means of the lean burn technology.

Advanced combustion engines dominate all automotive applications. Future high efficiency clean combustion engines can contribute significantly to sustainable transportation. Effective ignition strategies are studied to enable lean and diluted combustion under considerably high-density mixture and strong turbulences, for improving the efficiency and emissions of future combustion engines. Continuous discharge and multi-site ignition strategies have been proved to be effective to stabilize the combustion process under lean and EGR diluted conditions. Continuous discharge strategy uses a traditional sparkplug with a single spark gap and multiple ignition coil packs. The ignition coil packs operate under a specific time offset to realize a continuous discharge process with a prolonged discharge duration. Multi-site ignition strategy also uses multiple ignition coil packs.