船用增压柴油机不同负荷下燃烧排放性能研究

为了研究柴油机在不同运行工况下偏心燃烧室缸内燃烧及排放情况,采用三维流体数值分析软件AVL FIRE建立某型柴油机燃烧及排放的计算模型。通过对不同负荷下柴油机燃烧及排放的模拟,计算该型柴油机缸内压力、温度等参数随曲轴转角的变化及燃烧温度、燃空当量比、NO和Soot的分布情况。研究表明：随着负荷的增加,在高负荷下易出现燃油撞壁现象;NO生成量随着负荷的增大而增加,在负荷增大到一定值时反而减小;NO生成主要分布于燃烧室偏心侧,高工况时NO大量生成在燃烧室边缘;Soot主要集中在油束与缸盖之间的缝隙位置。

Study on diesel combustion and emissions under different load

In order to study the combustion and emissions of diesel at different operating conditions,a calculation model of diesel＇s combustion and emissions is established by using AVL FIRE,a three-dimensional computational fluid dynamics software.Through the simulation of diesel combustion and emissions at different load,the diesel engine cylinder pressure,temperature and other parameters changing with the crank angle and the distribution of combustion temperature,equivalence ratio and NO are studied.The results show that： With the load increasing,the fuel may hit the wall;the NO formation increases proportionally;but when the load increases to a certain value,the NO formation becomes decrease instead.The NO formation mainly concentrated at the eccentric combustion chamber,while under high load mainly at edge of the combustion chamber.Soot mainly concentrates in the oil gap between the beam and the cylinder head position.