撞击式射流破碎特性的实验研究
An Experimental Study on Breakup Characteristics of Impinging Jets

基于自行搭建的撞击式射流系统，采用高速摄影技术，研究了对称射流撞击和非对称撞击射流液膜的破碎 特性．分析研究了射流撞击夹角及喷嘴内径对射流撞击破碎的破碎模式和破碎特征(破碎长度、液膜长度、液膜宽 度、液膜长宽比)的影响规律．对比研究了3 种不同流体――水、甘油、卡波姆凝胶(非牛顿流体)的破碎特性．在 实验的韦伯数范围内，喷射模式可分为3 种破碎模式，即封闭液膜模式、开边界模式、液线液滴模式；破碎长度随 韦伯数的增大，呈先增大后减小的趋势；减小撞击夹角可以减小液膜的长宽比，喷嘴内径的大小不会改变液膜长宽 比的值；与对称撞击相比，非对称撞击更能加剧液膜的破碎．
An impinging jet system was developed and high-speed photography was applied to investigating the breakup characteristics of symmetric and asymmetric impinging jets．The effects of impinging angle and orifice diameter on the breakup patterns and breakup characteristics(breakup length，length of liquid film，width of liquid film，aspect ratio)were analyzed．A contrastive study was conducted to explore the different breakup characteristics of three kinds of liquid，namely water，glycerinum and Carbopol gel．In the Weber number range of the experiment，the spray patterns could be categorized into three types：closed rim，open rim with shedding droplets and bow shaped ligament．When the Weber number increases，the breakup length first increases and then decreases. The aspect ratio of liquid film decreases with the decrease of impinging angle and keeps constant with different orifice diameters．Compared with symmetric impinging jet，asymmetric impinging jet can accelerate the breakup of the liquid film to a greater extent