中文摘要：

在小负荷工况下,通过KIVA耦合PRF-PAH简化化学动力学机理,对柴油和正庚烷低温燃烧的燃烧过程进行三维模拟计算,对比分析了燃料挥发性对柴油机低温燃烧的影响.结果表明：正庚烷由于挥发性好,韦伯数大,燃油蒸发快,有效促进了缸内混合气的形成,使燃烧之前缸内混合气浓度分布梯度较柴油小,从而碳烟的生成量较柴油少.在较低喷油压力下,正庚烷相对柴油来说有效降低了碳烟峰值.这是由于燃料挥发性的改善弥补了低喷油压力对混合的不利影响,因此提高燃料挥发性可以降低低温燃烧对高喷射压力的需求.

英文摘要：

A reduced PRF-PAH mechanism is coupled with the KIVA CFD code to study the effects of fuel volatility on the mixing, combustion processes and soot emission in a low-temperature combustion diesel engine. Due to higher volatility and larger Weber number, the evaporation rate of n-heptane is higher than that of diesel, which effectively promotes the in-cylinder mixing process. Thus the concentration gradient with n-heptane fuel is smaller than that with diesel prior to the ignition and combustion. As a result, the soot emission of n-heptane is lower than that of diesel. N-heptane is also able to effectively reduce the soot emission under reduced injecting pressure compared with diesel. The reason is that higher volatility can overcome the adverse effects of low injection pressure on the mixing process. Therefore, for the optimization of fuel propertie, improving fuel volatility can reduce the demand for high injection pressure in low-temperature combustion.