M15甲醇柴油发动机喷雾及燃烧过程的数值模拟

The Numerical Simulation of Spray and Combustion of M15 Methanol-diesel Blends Engine

分别建立了纯柴油及甲醇-柴油混合燃料喷雾燃烧过程的多维数值模型,并用试验结果对计算模型进行了验证。模拟计算结果表明:在不改动柴油机结构的情况下,掺烧15%的甲醇后,滞燃期变长;喷雾贯穿距离缩短,破碎能力增强,油滴索特平均直径也有所降低,这表明掺烧甲醇后具有较好的喷雾均匀性;燃油浓度场均匀性改善,与空气混合效果更好;soot排放有明显改善;另外,进气涡流比对M15甲醇柴油发动机缸内湍动能的分布有较大的影响。

The multidimensional simulation models of diesel engine and methamol-diesel engine about their have been established,and were validated by experimental results.The results show that if 15% methanol（M15）is used in diesel engine without any variation of engine structure,the ignition delay period becomes longer,the penetration length is shorter,the break-up capability boosts up and the sauter diameter of droplet decreases,which suggests that the methanol-diesel blends engine has better spray characteristics.Moreover,it shows that M15 has a better mixing with air,the concentration field is more uniform and the soot emission is much lower.In addition,for M15 methanol-diesel blends engine,the swirl ratio has great influence on the distribution of turbulent kinetic energy of the cylinder.