高韦伯数液滴撞壁诱导的中间射流破碎现象  

Phenomenon of Central Jet Breakage Induced by High-Weber-Number Droplet Impact

作　　者：范隆杰 吴晗[1] 岑春泽 李佳峰 刘福水[1] Fan Longjie;Wu Han;Cen Chunze;Li Jiafeng;Liu Fushui(School of Mechanical Engineering,Beijing Institute of Technology University,Beijing 100081,China)

机构地区：[1]北京理工大学机械与车辆学院,北京100081

出　　处：《燃烧科学与技术》2019年第3期197-203,共7页Journal of Combustion Science and Technology

基　　金：国家自然科学基金资助项目(51806014)

摘　　要：针对内燃机缸内附壁油膜问题,模拟液滴撞壁过程,设计开发了气体驱动单液滴高速撞击热壁面试验系统.研究了液滴高速撞壁对二次雾化的影响,同时考虑壁面温度对撞击效果的影响.结果表明,目前液滴撞壁研究的韦伯数范围多是20～1 000,而通过使用驱动气体(氮气)将小液滴加速至10.8 m/s,从而产生碰壁韦伯数高达4 057的液滴;液滴在韦伯数高达一定条件下发生射流破碎现象,热效应并不是唯一导致其产生的因素;随着韦伯数的增加,射流高度及产生的次级液滴数量也随之增加;随着壁面温度升高,发生中间射流现象时的韦伯数随之降低;在高韦伯数条件下,在远高于水的Leidenfrost临界温度时并没有明显的Leidenfrost现象产生.In consideration of the problem of fuel film on the cylinder wall in an internal combustion engine, the process of droplet impact was simulated in this paper. A test system was designed and developed in which a gas- driven single-droplet impacted the hot wall at high speeds.The effect of high-speed droplet impact on the secondary atomization was studied,and the influence of wall temperature on the impact effect was also considered. Com- pared with the Weber number range of mostly 20 1 000 from current studies on droplet impact,the speed of droplets accelerated to 10.8 m/s by using the driving gas(i.e.,nitrogen),thereby generating droplets with a Weber number of up to 4 057. The phenomenon of jet breakage occurred when the Weber number grew to a certain value,so the thermal effect was not the only inducing factor. As the Weber number grew,the jet height and the number of resulting secondary droplets increased accordingly. With the growth of wall temperature,the Weber number decreased as the central jet occurred. Under the condition of high Weber number,no obvious Leidenfrost phenomenon occurred at the temperature much higher than the Leidenfrost temperature of water.

关 键 词：液滴撞壁 壁面温度 高韦伯数 中间射流 

分 类 号：TK407.9[动力工程及工程热物理—动力机械及工程]