Abstract: The flow characteristics in a free three impinging jets reactor with the constant nozzle diameter of 1 mm were studied using high-speed digital camera. The effects of injection Reynolds number Reinj, distance between opposed nozzles d1, vertical distance between the vertical nozzle and opposed nozzles d2 on flow characteristics were examined. The experimental results showed that the effect of Reinj on flow structure was more significant at the flow rate ratio of 2. With increasing of Reinj, the flow structure was changed from a regular succession of ligaments to umbrella, finally becoming a structure composed of ligaments and droplets violent flapping which splashed around irregularly, performing high degree of atomization of the liquid sheets and intense perturbation of the edge of the liquid sheet, providing excellent mixing effect. Due to the small value of d1, the impinging zone close to the opposed nozzles, nozzle blocking could occur, leading to poor mixing. As d2 increased, the flow structure was slightly changed from a regular succession of ligaments to a small area of umbrella structure due to the effect of gravity at Reinj=1699. By using iodide-iodate parallel-competitive reaction system, compared with conventional impinging jets reactor, the value of segregation index of three impinging jets reactor was 1/2 as that of conventional impinging jets reactor at the flow rate ratio of 8, which led to higher micromixing efficiency.

Key words: three impinging jets reactor, flow characteristic, mixing, umbrella structure

摘要： 采用高速数码相机对喷嘴直径1 mm的开放式三股对撞式撞击流反应器内的流场特性进行研究，考察了入口雷诺数Reinj、对置两管喷嘴间距d1、垂直管喷嘴到对置两管的垂直距离d2对流场特性的影响. 结果表明，在物料流量比为2时，Reinj对流体结构的影响较显著. 随Reinj增加，流体结构由链状向类似伞状变化，最终破碎成液滴，无规则向四周分散，雾化程度显著增加，撞击面边缘剧烈扰动，提供了较好的混合效果. 较小的d1使撞击区域接近对置两管喷嘴处，可能导致喷嘴堵塞而影响混合效果. 增大d2及Reinj=1699时，重力影响使流体结构由链状轻微向面积较小的伞状结构变化. 采用碘化物-碘酸盐平行竞争反应体系，物料流量比为8时，与传统撞击流反应器相比，三股对撞式撞击流反应器的离集指数约为其1/2，显示出优越的微观混合性能.

关键词: 三股对撞式撞击流反应器, 流动特性, 混合, 伞状结构