摘要： 考虑到OH基的氧化作用,将OH基氧化模型嵌入KIVA-3V软件内,应用在柴油机排放计算中,验证了模型的正确性,分析了EGR率(5％,10％,15％,20％ 和25％)对柴油机碳烟排放的影响.结果表明:计算得到的碳烟排放与测量值吻合较好;与原碳烟氧化模型相比,修正的氧化模型能较好地预测碳烟排放;EGR率增加,小负荷下的碳烟排放增加幅度较小,中高负荷下的碳烟排放增加幅度较大,特别是在大EGR率时,碳烟排放增加幅度更大;EGR率增加时,碳烟生成量和氧化量均减少,氧化量减少更多,高质量浓度碳烟分布区域更广;EGR率对OH基的抑制作用在燃烧中期较为明显,而且负荷越大,OH基体积分数随EGR率的加大变得越低.
Abstract
The oxidation model by hydroxyl group was embedded into KIVA-3V to investigate the emission of DI diesel engine and to verify the model. The effects of EGR ratios of 5%, 10%, 15%, 20% and 25% on soot emission were discussed. The results show that the calculated soot emission is good consistent with measured result. The improved oxidation model can predict soot emission well. When the EGR ratio increases, soot emission increases slightly at low load, and increases much at middle or heavy load, especially increases much more for high EGR ratio. With the increasing of EGR ratio, soot oxidation mass decreases more than soot production mass with wide distribution of high soot mass concentration. The inhibition effect of EGR on hydroxyl group is obvious at the middle stage of combustion. When the load increases, the concentration of hydroxyl group decreases markedly with the increasing of EGR ratio.
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