喷孔参数对高压共轨船用柴油机燃烧与排放影响的仿真研究

Simulation Research on Effect of Nozzle Parameters on Combustion and Emissions for HPCR Marine Diesel Engine

为研究喷孔参数对高压共轨船用柴油机燃烧与排放的影响,应用三维CFD软件对采用3种不同喷孔方案的某船用柴油机燃烧流场和排放进行了数值计算,计算的缸内示功图与实测结果基本吻合。模拟得到了不同喷孔方案下的燃油液滴分布、流场分布、缸内燃烧温度和压力分布,以及NOx和Soot质量分数分布等,同时还得到了油耗与指示功率。对比分析表明:喷孔直径和数目影响燃油雾化和蒸发,影响油气混合质量,进而影响NOx与Soot的排放。通过综合考虑动力性、经济性和环保性,选择喷孔孔数为8、喷孔直径为0.37 mm的喷孔方案为最优方案。

In order to research the effect of nozzle parameters on combustion and emission characteristics of high-pressure common-rail（HPCR） marine diesel engine,the combustion process and emissions of a marine diesel engine equipped with three types of nozzles were tested on the bench and calculated using three-dimensional CFD software.The simulated indicated diagram was basically agreed with the measured data.The fuel droplet behavior,the in-cylinder flow field,combustion temperature and pressure distributions,the NOx and soot mass fraction with different nozzles were available.Indicated power and specific fuel consumption were also obtained.Analysis shows that both spray orifice number and diameter of the nozzle affect fuel atomization and evaporation,impacting fuel and air mixing,and further affecting NOx and soot emissions.By synthetically considering engine power,economy and emissions,the optimal nozzle scheme is orifice number of 8 and diameter of 0.37 mm.