液滴间相互碰撞融合与破碎的实验研究Experimental study on collision coalescence and breakage between droplets
张涛,陈君,李永平,宋新河,杨蕊,吕明
摘要(Abstract)：
液滴间的相互碰撞对发动机液体燃料雾化、燃烧效率及颗粒物排放的减少均有重要影响;为了探究液滴间相互碰撞后的液滴融合与破碎过程,采用高速摄影技术对液滴间相互碰撞的融合过程、融合振荡无量纲宽长比变化历程、破碎过程以及液体物性参数对碰撞破碎的影响进行了分析。结果表明,液滴间相互碰撞后主要呈现融合振荡与破碎两种运动形态;对融合振荡形态而言,两液滴间的碰撞速度及初始无量纲尺寸比越大,融合后液滴振荡的宽长比的最大值越大;对破碎形态而言,两液滴间的碰撞速度越大、初始无量纲尺寸比越小以及大液滴的表面张力越小,液滴发生破碎的时刻越小。研究结果可以为改善发动机缸内雾化,增大气/液间的接触面积,强化气/液间传热传质提供理论依据。
关键词(KeyWords)： 液滴间碰撞;尺寸比;相对速度;破碎时刻
基金项目(Foundation): 北京市自然科学基金(3184064,3182030)
作者(Author): 张涛,陈君,李永平,宋新河,杨蕊,吕明
参考文献(References)：
- [1]李建军.低速流体撞击射流破碎的实验研究[D].天津:天津大学, 2015.LI J J. Experimental study on breakup characteristics of impinging jets with low velocity[D]. Tianjin:Tianjin University, 2015.
- [2]贺萍,刘永长,宋军,等.喷雾碰壁对喷雾混合特性的影响[J].车用发动机, 1995(1):11-15.HE P, LIU Y C, SONG J, et al. Effect of spray impingement on the fuel spray mixture characteristic[J]. Vehicle Engine, 1995(1):11-15.
- [3] QUAN S, LOU J, SCHMIDT D P. Modeling merging and breakup in the moving mesh interface tracking method for multiphase flow simulations[J]. Journal of Computational Physics, 2009, 228(7):2660-2675.
- [4]李强,蔡体敏,何国强,等.液滴碰撞和聚合模型研究[J].应用数学和力学, 2006, 27(1):60-66.LI Q, CAI T M, HE G Q, et al. Droplet collision and coalescence model[J]. Applied Mathematics and Mechanics, 2006, 27(1):60-66.
- [5]魏明锐,文华,刘永长,等.喷雾过程液滴碰撞模型研究[J].内燃机学报, 2005, 23(6):518-523.WEI M R, WEN H, LIU Y C, et al. Modeling study on droplets collision in spray process[J]. Transactions of CSICE, 2005, 23(6):518-523.
- [6]刘泽军,张超.气相中双液滴正碰过程数值模拟研究[J].计算力学学报, 2015, 32(1):136-141.LIU Z J, ZHANG C. Numerical simulation of head-on binary collision of droplets in gas phase environment[J]. Chinese Journal of Computational Mechanics, 2015, 32(1):136-141.
- [7]王程遥,张程宾,陈永平,等.剪切流场下液滴碰撞的流变特性[J].东南大学学报, 2015, 45(2):309-313.WANG C Y, ZHANG C B, CHEN Y P, et al. Rheological behavior of interactive drops in shear flow[J]. Journal of Southeast University, 2015, 45(2):309-313.
- [8] NOBARI M R, JAN Y, TRYGGVASON G. Head-on collision of drops-A numerical investigation[J]. Physics of Fluids, 1996,8(1):29-42.
- [9] MELEáN Y, SIGALOTTI L D G. Coalescence of colliding vander Waals liquid drops[J]. International Journal of Heat&Mass Transfer, 2005, 48(19/20):4041-4061.
- [10]刘栋.液滴碰撞及其融合过程的数值模拟研究[D].北京:清华大学, 2013.LIU D. Numerical simulations on collision and coalescence of binary droplets[D]. Beijing:Tsinghua University, 2013.
- [11] ASHGRIZ N, POO J Y. Coalescence and separation in binary collisions of liquid drops[J]. Journal of Fluid Mechanics, 2006,221(1):183-204.
- [12] JIANG Y J. An experimental investigation on the collision behaviour of hydrocarbon droplets[J]. Journal of Fluid Mechanics,1992, 234(1):171-190.
- [13] ADAM J R. The collision, coalescence, and disruption of water droplets[J]. Journal of Applied Physics, 1968, 39(11):5173-5180.
- [14] PAN K L. Experimental and mechanistic description of merging and bouncing in head-on binary droplet collision[J]. Journal of Applied Physics, 2008, 103(6):064901-064901-11.
- [15] GAO T C, CHEN R H, PU J Y, et al. Collision between an ethanol drop and a water drop[J]. Experiments in Fluids, 2005, 38(6):731-738.
- [16] GUNN R. Collision characteristics of freely falling water drops[J]. Science, 1965, 150(3697):695-701.