关键词: 三股对撞式撞击流反应器, 流动特性, 混合, 伞状结构

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