柴油机双层多孔喷油嘴瞬态流动特性  

Transient flow characteristics of double-layer arrangement of diesel nozzle

作　　者：王谦[1] 李念[1] 何志霞[1] 钟汶君[1] 高志胜[1] 

机构地区：[1]江苏大学能源与动力工程学院,江苏镇江212013

出　　处：《江苏大学学报（自然科学版）》2015年第4期373-379,共7页Journal of Jiangsu University：Natural Science Edition

基　　金：国家自然科学基金资助项目(51276084);江苏省科技支撑(工业)计划项目(BE2010198)

摘　　要：以某型国产喷油器喷油嘴为对象,在X射线精确测量其几何参数的基础上,采用动网格技术对喷油嘴内部瞬态流动进行模拟研究,并通过可视化试验验证所建模型的准确性.研究了不同位置处、不同喷射压力下喷孔内流量系数、气相体积分数随针阀运动的变化,分析了燃油性质对喷孔内流动特性的影响.结果表明:在相同的喷油压力下,上层喷孔与下层喷孔相比,空穴现象会提前出现,且空穴发展更加迅速,空穴区域更大;针阀关闭阶段与针阀开启阶段相比,喷油嘴内部空穴发展较快,喷嘴内空穴在针阀关闭的前一刻会瞬间增加;喷油压力增加,空穴现象产生时刻提前,空穴发展区域增大;进出口压力相同时,喷孔内空穴现象的发展及其强度受燃油运动黏度、饱和蒸汽压和密度的影响.A certain type of domestic fuel nozzle was investigated,and the accurate geometric parameters were measured by X-ray. A moving mesh generation strategy was applied for 3D simulation of the nozzle cavitation flow. A visualization experiment of inside nozzle flow was used to validate the calculated results. The effects of needle movement on the development of cavitation flow and flow characteristic parameters of discharge coefficient and gas volume fraction were investigated at different nozzle hole position and under different injection pressure. The influence of fuel oil on flow characteristics inside the nozzle was also investigated. The results show that under the same injection pressure,compared with the lowerlayer holes,the cavitation in the upper-layer holes appears earlier and develops more quickly,and the area is larger. Compared with the opening stage of needle valve,the cavitation in the closing stage develops more quickly,and instantaneously increases at the moment of needle valve shutting. With the increasing of injection pressure,the happen moment of cavitation appears earlier,and the area becomes more larger. Under the same injection condition,the kinematic viscosity,the saturated vapor pressure and the density of fuel oil also have influence on the cavitation inside injector nozzle.

关 键 词：柴油机 喷油嘴 针阀运动 空穴 数值模拟 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]