液体性质对气泡雾化液滴不稳定性的影响  

Influence of liquids properties on unsteadiness of droplet in effervescent sprays

作　　者：刘猛[1] 段钰锋[1] 张铁男[1] 李华峰[1] 

机构地区：[1]东南大学能源与环境学院,南京210096

出　　处：《东南大学学报（自然科学版）》2012年第2期295-300,共6页Journal of Southeast University：Natural Science Edition

基　　金：国家重点基础研究发展计划(973计划)资助项目(2010CB227001);浙江大学能源清洁利用国家重点实验室开放基金资助项目(ZJUCEU2010010)

摘　　要：为了改善气泡喷嘴雾化性能,利用基于液滴统计学的理想雾化理论模型研究了液体性质对气泡雾化液滴不稳定性的影响.同时,采用高速摄影技术分析了气泡喷嘴内部气液两相流动及喷口雾化状况,探究了雾化液滴产生不稳定现象的根本原因.实验结果表明,气泡喷嘴雾化本身具有不稳定性,且雾化下游场中不同粒径的液滴均表现出不稳定性.当喷嘴内部气液两相处于气泡流时,喷口处单个气泡的破裂可导致雾化下游场中液滴不稳定;当气液两相处于过渡流时,单个气泡、液体以及较长气柱交替流经喷口会造成气泡雾化液滴不稳定;当气液两相处于环状流时,液桥现象的存在致使雾化下游场液滴不稳定.增加牛顿流体的黏度或者降低非牛顿流体剪切变稀的强度能够有效降低雾化液滴的不稳定性.In order to improve the atomization performance of an effervescent atomizer, the influ- ence of fluid properties on the unsteadiness of droplets in effervescent sprays was investigated by using the ideal spray theory model based on the droplet statistics. Gas-liquid two-phase flow patternin nozzle and the atomization near the discharge orifice were analyzed by the high-speed photography to explore the root cause of droplets＇ unsteadiness. The experimental results show that the efferves- cent atomization is an inherently unsteady process and the droplets with all sizes in the downstream ofeffervescent sprays exhibit unsteady behavior. When the gas-liquid two-phase flow in nozzle belongs to the bubble flow, the rapidly expanding bubbles can induce the unsteadiness of the droplets. When the gas-liquid two-phase flow belongs to the intermittent flow, the alternate flow of a single bubble,liquid and a long gas column through the jet can lead to the unsteadiness of the droplets. In addition, the presence of liquid bridges in annular regime can also cause the unsteadiness of the droplets. The increase of the viscosity of the Newtonian fluid and the reduction of the shear-thinning strength of thenon-Newtonian fluid can reduce the level of spray unsteadiness.

关 键 词：气泡雾化 理想雾化 稳定性 非牛顿流体 气液两相流 

分 类 号：O359.1[理学—流体力学]