层叠流道中天然高分子挤压流动过程的数值模拟

为探究层叠流道中天然高分子材料挤压流动过程与混合特性，建立层叠流道的三维物理模型和有限元网格模型，利用POLYFLOW软件计算了食品熔体在不同的入口流量，挤压过程中的压力、速度、剪切速率分布。结果表明，压力沿着挤出方向呈梯度递减，随着入口流量增大中间位置压力差增大；剪切速率在流道中变化明显，剪切速率从流道中间位置向四周递减，从壁面到流道内部递减；速度在流道内沿着挤出方向先增大后减小，靠近壁面速度小；层叠扭转流道的结构和尺寸设计，有助于提高天然高分子物料的混合效果，并且第1、4层流道混合效果优于第2、3层流道，提高入口流量也有利于提高物料的混合效果。

Numerical simulation of extrusion flow process of natural polymers in laminated flow channels

To explore the extrusion flow process and mixing characteristics of natural polymers in the stacked flow channel， a three⁃dimensional physical model and a finite element mesh model of the stacked flow channel were established. The POLYFLOW software was used to calculate the flow rate of the food melt and the distributions of pressure， velocity， and shear rate during the extrusion process. The results indicated that the pressure decreased in a gradient along the extrusion direction， and the pressure difference at the middle position increased with an increase in the inlet flow rate. There is a significant change in shear rate in the flow channel. The shear rate tended to decrease from the middle position of the flow channel to the periphery and from the wall surface to the surrounding area. The speed increased at first and then decreased along the extrusion direction in the flow channel. The speed presented a small value near the wall surface. The structure and size design of the stacked twist flow channel can help to improve the mixing effect of natural polymers. The mixing effect in the 1^st and 4^th layer runners was better than that in the 2^nd and 3^rd layer runners. An increase in the inlet flow was also beneficial to the improvement of mixing effect.