高原低氧环境下含氧燃料对柴油机工作过程的影响

以高原共轨柴油机为研究机型，根据台架试验和发动机结构参数，运用A V L Fire构建其燃用B100（纯生物柴油）和B70N30（体积70％生物柴油＋30％正丁醇）的三维CFD模型，并进行验证。利用该模型对比研究了不同海拔氧浓度对发动机燃用不同含氧燃料工作过程的影响规律，并在此基础研究了B70N30耦合EGR对发动机的影响机理。计算结果表明：相比D100（纯柴油），B100和B70N30的缸内局部当量比降低，活性自由基（OH ，O）浓度及其缸内分布区域增大，从而导致NO排放升高，但同时使CO生成量峰值减小，Soot和CO缸内分布区域以及排放终值都随大气氧浓度的降低而显著减少；相比B100，B70N30因汽化潜热增大，其NO排放降低，但原子氧的增加导致Soot和CO同时降低；对于B70N30，随EGR率增大，NO大幅度降低，CO显著升高，而Soot因滞燃期延长变化较小。

Influence of Oxygen-enriched Fuel on Diesel Engine Working Process under Hypoxia Condition at Plateau

A 3D CFD model of common rail diesel engine fueled with B100 pure bio‐diesel and B70N30 blended fuel composed of 70% bio‐diesel and 30% butanol was built according to the bench test and engine structure and was further verified .With the model ,the influences of oxygen concentration at different altitudes on working process of engine fueled with different oxy‐gen‐enriched fuels were researched and the influence mechanism of B70N30 and EGR was further analyzed .The results showed that the in‐cylinder local equivalence ratio of B100 and B70N30 was lower and the concentration and distribution area of OH and O active free radicals were larger compared with D100 pure diesel fuel .Consequently ,the NO emission increased ,the peak val‐ue of CO production decreased and the in‐cylinder distribution area and final emission of soot and CO decreased obviously with the decrease of oxygen concentration .Compared with B100 ,the NO emission of B70N30 decreased due to the increase of gasifi‐cation latent heat and the soot and CO emission decreased simultaneously due to the increase of atomic oxygen .Besides ,the NO emission decreased greatly ,the CO emission increased significantly and the soot emission kept nearly unchanged due to the pro‐longing of ignition delay with the increase of EGR rate when B70N30 was fueled .