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本文在定容燃烧弹中利用高速摄像技术研究了柴油在甲烷/空气和甲醇/空气氛围中低温着火特性,并基于正庚烷/甲烷简化机理和正庚烷/甲醇骨架机理,对比分析了两种二元燃料的低温氧化路径.试验和模拟结果均表明甲烷和甲醇都能使柴油着火时刻推迟,且甲醇推迟作用更明显,柴油推迟着火现象随甲烷和甲醇当量比增大而更明显,随环境温度升高而减弱.反应路径分析表明,甲烷和甲醇的脱氢反应消耗了大量OH抑制了正庚烷着火,甲醇抑制作用强于甲烷原因在于甲醇消耗OH速率快,且只通过低温下很稳定的H2O2分解向自由基池中提供OH,而甲烷消耗的OH少,还能通过链传递反应(CH3+HO2=CH3O+OH)贡献相当数量的OH.“,”The ignition characteristics of diesel in premixed methane-air and methanol-air mixture atmospheres (MeAA and MoAA) at low temperature were studied respectively in a constant volume combustion chamber equipped with a high-speed camera.Using the reduced reaction mechanism of n-heptane/nethane fuel blends and the skeletal reaction mechanism of n-heptane/methanol fuel blends respectively,the oxidation processes at low temperature of these dual fuels were studied by Chemkin-Pro.Results show that,in MeAA and MoAA,ignition delays of diesel become longer;flame lift-off lengths get longer;and flame natural luminosity become weaker.These trends in MoAA are more noticeable than those in MeAA,and these phenomena become more significant with equivalent ratios of methane and methanol increase and initial temperature decrease.Analyses of reaction paths show that,OH is consumed in large quantities by dehydrogenation of methane and methanol,which leads to the activity of the whole reaction system reduced.So ignition delays of n-heptane are prolouged.The rate of methanol dehydrogenation is more quick than methane,so the consumption rate of OH by methanol is also more quick.While the troduction of OH is only through the decomposition of H2O2,which is stable at low temperature,in methanol oxidation process.However,methane dehydrogenation consumes less OH than methanol,and reaction CH3 + HO2 =CH3O + OH in methane oxidation process can provide abundant OH to the radical pool.All these factors result in the inhibition for n-heptane ignition by methanol is stronger than methane.