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设计了在进气道处增加Laval喷管来改变喷油参数,促进燃油与空气混合,以实现HCCI的燃烧条件.使用Star-CD软件对此设计过程的柴油机喷射及燃烧进行数值模拟试验.计算结果表明:利用Laval管实现进气道超音速气流方式喷射燃油(称为前者)其粒子直径的分布范围比缸内直喷方式(称为后者)要均匀的多,也小得多;后者燃油蒸发速度比前者要快;前者因缸内燃油浓度过分均匀而导致压燃时温度较低.分析认为,此方法可使燃油雾化效果明显增强,但并未引起燃烧温度的剧烈变化.
Designed to increase the Laval nozzle at the inlet to change the fuel injection parameters and promote the mixing of fuel and air in order to achieve the HCCI combustion conditions.Numerical simulation experiments were carried out on the injection and combustion of diesel engine using Star-CD software. The results show that using Laval tube to achieve intake air supersonic jet injection of fuel (known as the former), its particle diameter distribution is much more uniform and smaller than that of in-cylinder direct injection (the latter) The former is faster than the former due to the excessively uniform fuel concentration in the cylinder.The analysis shows that this method can significantly enhance the fuel atomization effect but does not cause dramatic changes in the combustion temperature.