Kenics型静态混合器的结构优化与数值模拟

Numerical simulation and structure optimization of Kenics static mixers

基于三维有限元数值模拟方法,对应用于高黏聚酯熔体直纺工业丝过程中熔体管道输送的Kenics型静态混合器进行结构优化;对静态混合器内示踪粒子的流动轨迹进行统计学处理,通过停留时间分布、分离尺度、面积伸展率以及时间平均效率表征流动特性与混合性能。结果表明:相比传统静态混合器,当静态混合器的元件旋转角度为120°时,静态混合器的分离尺度降低,分散混合能力增强,拉伸作用增强,混合特性提高;相同管径下元件长径比为0.75时,静态混合器的混合能力较长径比为1.00或1.25时都有明显的提高;随元件长径比增加,混合效果逐渐变差,流动方式趋近于理想平推流动。

Based on three-dimensional finite element numerical simulation method,the structure of Kenics static mixer for high-viscosity polyester melt pipeline transportation was optimized.Tracer particle trajectory in static mixer was statistically analyzed.The flow characteristics and mixing performance of the static mixer were characterized according to residence time distribution,separation scale,area extensional proportion and time-averaged efficiency.The results showed that as compared with traditional static mixers,the static mixer had the separation scale decreased and the dispersive mixing ability,stretching effect and mixing characteristics improved when the rotating angle of the static mixer was 120°;the mixing ability of the static mixer with the component length-diameter ratio of 0.75 was obviously improved under the same pipe diameter,as compared with those of static mixers with the length-diameter ratio of 1.00 and 1.25;and the mixing effect became worse gradually and the flow pattern tended to be ideal push flow with the increase of the length-diameter ratio of components.