In order to explore the mechanism of high-speed diesel engine combustion system parameters on the combustion properties, the matching laws between fuel injection system parameters and combustion chamber structures in high speed direct injection ( HSDI) diesel engine was studied by using three-dimensional CFD numerical simulation method. The spatial distribution of fuel vapour and characteristics of fuel /air mixing were analyzed. In order to quantitatively describe the performance of fuel/air mixing, the parameters about the rate of turbulent mixing and concentration variance of mixture were established. Moreover, weight analysis of the effect of fuel injection system and combustion chamber structural parameters on indicated power was carried out using orthogonal method. The results show that diesel engine power decreases after increasing with the increase of chamber caliber-depth ratio. When the caliber-depth ratio equals to 6. 4, diesel engine is the most powerful, mixing is the most uniform. For different combustion chamber, fuel injection system parameters are of different weights for power. With the combustion chamber caliber-depth ratio increases, the weight of injection pressure decreases, the weight of spray angle of increases, the weight of nozzle number and diameter reduces, the weight of injection timing decrea-ses and then increases.%为深入探究高速柴油机燃烧系统参数对燃烧性能的作用机制,采用多维数值模拟方法,研究了高速直喷(HSDI)柴油机喷油系统参数与燃烧室结构参数对燃烧过程的影响规律,并结合缸内燃油蒸气空间分布和油气混合等特性对燃烧系统参数的影响规律进行了分析.为了定量描述由气混合特性,引入了湍流混合速率和混合气浓度方差的概念.另外,采用正交方法开展了喷油系统和燃烧室结构参数对指示功率影响的权重分析.结果表明:对于研究的燃烧系统,柴油机指示功率随燃烧室径深比的增加先增后减,径深比6.4时功率最大,且此时油气混合最均匀.针对不同径深比燃烧室,喷油系统参数对功率的影响权重不同.随着燃烧室径深比增大,喷油压力的影响权重减小.油束夹角的影响权重增大,喷孔数、孔径的影响权重减小.喷油定时的影响权重先减小后增大.
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