摘要
为了更好地了解柴油机喷孔内燃油空化流动特性,基于空化数和几何结构相似原理,采用比例放大试验装置,并结合CFD三维仿真,研究了喷孔出口截面处空化过程及空化过程对出口截面燃油流动速度、密度分布及湍动能的影响.分析了在保持入口压力不变的工况下,出口截面空化流动随背压改变的变化规律.研究表明:当入口压力不变,随背压降低,喷孔入口截面空化区先增大后稳定,喷孔出口截面空化区及燃油密度随背压的降低而减小;喷孔出口截面的湍动能随背压降低而不断增大,其中空化饱和阶段湍动能增加率小于无空化及空化发展阶段;喷孔出口截面与入口截面的液相平均流速在无空化阶段相差不大,而在空化发展阶段及空化阻塞阶段,两者相对速度不断增大.
In order to study the cavitation fuel flow characteristics inside the dieselnozzle,based on the same cavitatio nnumber and the similar structure of th ebaseline nozzle,the flow characteristics of the nozzle were tested on the optical test rig,together with the CFD three-dimensional simulation.Aninvestigation on the characteristics at the nozzle outlet during the cavitation period,and the influence of cavitation on the flow characteristics such as the velocity,the density,and the turbulence kinetic energy were presented.The flow characteristics at the nozzle outlet were analyzed as the back pressure decreased.The results show that for stable inlet pressure,cavitation at inlet cross-section becomes first stronger and then stable as the back pressure drops.At the nozzle outlet,the cavitation and the fuel density continue increasing with the decrease in the back pressure.The turbulent kinetic energy constantly increases with back pressure decreasing in the nozzle.However,the cavitation increase rate at saturation stage is less than that of without cavitation and cavitation developing period.During the no cavitation stage,the liquid average velocity has no difference at the inlet and outle tcross-section of nozzle,but the velocity difference between the nozzle inlet and the outlet increases during both the cavitation developing and saturation periods.
作者
雷艳
高壮
桑海浪
宋鑫
代贺飞
仇滔
LEI Yan;GAO Zhuang;SANG Hailang;SONG Xin;DAI Hefei;QIU Tao(College of Environment and energy engineering,Beijing University of Technology,Beijing 100124,China;;Guangxi Yuchai Machinery Group Co.,Ltd.,Yulin 537005,Guangxi,China)
出处
《北京工业大学学报》
CAS
CSCD
北大核心
2018年第9期1233-1238,共6页
Journal of Beijing University of Technology
基金
国家自然科学基金资助项目(91641106)
北京市自然科学基金资助项目(3172007)
关键词
柴油机
喷孔
空化
数值模拟
diesel engine
nozzle
cavitation
numericals imulation
作者简介
雷艳(1976—),女,副教授,主要从事内燃机节能与净化技术、燃油流动及仿真计算方面的研究,E-mail:leiyan@bjut.edu.cn
