重型车用柴油机低排放直喷燃烧系统参数的优化

在车用柴油机上引用缩口低排放型燃烧室后，燃烧系统向直喷化发展。为了掌握和定量地评价这种新型燃烧室的结构及其内部气流特点，引入了涡流强度保持性的概念。并利用商用软件FIRE对这种新型直喷式燃烧室内气流的空间分布及其时间变化规律进行数值计算，结合MATLAB软件计算燃烧室内的瞬态涡流强度保持性大小，由此分析不同燃烧室结构参数对燃烧室内气流特性及其涡流强度保持性的影响。同时，通过台架试验分析这种燃烧室内的不同涡流强度保持性与喷射系统参数和进气涡流等参数匹配时对柴油机性能和排放特性的影响。结果表明，通过低排放缩口型燃烧室结构参数的优化，可有效地组织和控制燃烧室内气流分布规律及其强度，而且对于这种燃烧室结构存在着最佳的喷射位置和进气涡流强度，使得在动力性和经济性基本保持不变的条件下，可有效地改善柴油机的排放特性。

Arameter Optimization for Low Emission DI Combustion System of Heavy-Duty Automotive Diesel Engine

Combustion system is developing into the direct injection trend with the introduction of reentrant type combustion chamber for diesel engine. The swirl intensity retention concept is introduced to evaluate the new shape of combustion chamber and its flow characteristics. Simulation on flow field is simulated and analyzed by software FIRE. The swirl intensity retention is calculated by combining MATLAB and the effect from different alyzed. Meanwhile, through combustion chamber configuration parameters on swirl intensity retention is an bench experiment, the influence on engine performance and emissions matching by different swirl intensity retention with fuel injection system parameters and intake swirl ratio is analyzed. The results show that proper reentrant combustion chamber can effectively organize and control the flow distribution and intensity in the combustion chamber. There exists an optimized fuel injection position and intake swirl ratio for this kind of combustion chamber to decrease engine emission without scarifying engine power output and fuel economy.