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以单缸直喷柴油机为研究背景,考虑了正十四烷(C14H30)燃料的详细化学反应机理,设计了化学成分的焓值计算程序,对缸内燃烧过程进行三维数值模拟计算,研究了诱发碳烟颗粒先导物生成的单环及多环芳香烃(PAHs)的形成,应用Belardini碳烟模型讨论了缸内碳烟颗粒的形成和演变过程,分析了PAHs对碳烟生成的影响.结果表明:缸内压力变化趋势的计算结果与实验模拟结果基本符合;芳香烃及PAHs的质量在急燃期急剧升高,而后迅速下降,并在燃烧后期达到一个稳定值;苯、苯乙炔、奈、菲的排放量较大,所采用的详细化学反应机理可以较好地反映复杂燃烧情况下多环芳香烃PAHs类中间物质、自由基等的生成机理.
Taking a single cylinder direct injection diesel engine as a research background, the detailed chemical reaction mechanism of n-tetradecane (C14H30) fuel was taken into account. The calculation program of enthalpy of chemical composition was designed and three-dimensional numerical simulation of in-cylinder combustion process was carried out. The formation of monocyclic and polycyclic aromatic hydrocarbons (PAHs) from soot precursors was discussed. The formation and evolution of in-cylinder soot particles were discussed with Belardini soot model. The effects of PAHs on soot formation were analyzed. The results of the calculation of the variation trend of in-cylinder pressure are in good agreement with the experimental results. The mass of aromatic hydrocarbons and PAHs increases sharply in the acute combustion period and then decreases rapidly and reaches a steady value in the late combustion stage. The contents of benzene, phenylacetylene, The emission of phenanthrene is larger, and the detailed chemical reaction mechanism adopted can better reflect the formation mechanism of polycyclic aromatic hydrocarbons (PAHs) intermediates and free radicals under complicated combustion conditions.