预燃室湍流射流点火甲醇发动机稀薄燃烧和排放特性试验研究OA北大核心CSTPCD

The combustion characteristics,engine performances and emission characteristics of a pre-chamber turbulent jet ignition(TJI)methanol engine were investigated experimentally by a four-stroke single-cylinder engine.The results show that,TJI combustion mode has a higher burning rate,and the heat release rate(HRR)peak is higher than that of spark timing(SI)combustion mode.Meanwhile,the ignition delay and combustion duration of TJI combustion mode is significantly shorter.As the excess air coefficient increases,both the in-cylinder pressure and HRR peak decrease,and the ignition delay and combustion duration increase under TJI and SI combustion modes.Moreover,TJI combustion mode can improve the combustion stability of the methanol engine under lean combustion conditions,and the lean limit can be expanded to the excess air coefficient λ=2.0.TJI combustion mode has a slightly lower indicated mean effective pressure(IMEP)in comparison to SI mode,while it has a lower indicated specific fuel consumption(ISFC)under the conditions of λ>1.1,indicating that TJI combustion mode has a better fuel economy,and the ISFC is less than 570 g/(kW·h)at the condition of λ=1.3.The NOx emission of TJI combustion mode is less than that of SI combustion mode,a reduction of 37.2%was observed at the condition of λ=1.1,and the CH2O and HC emissions are also lower at the ultra-low combustion condition of λ>1.3.