嵌入式行星螺杆挤出机内流场混沌行为研究

Study on Chaotic Mixing Performance in Flow in a Embedded Planetary Screw Extruder

基于有限体积方法,对嵌入式行星螺杆挤出机内流场进行了三维等温数值模拟。通过简化的物理模型来模拟螺杆的几何结构,使用用户自定义程序设定了行星螺杆运动的边界条件。分析了挤出机螺槽内压力和速度的分布;使用粒子追踪技术观察了螺杆内流体运动轨迹和粒子分布规律;对粒子在螺杆内的停留时间分布进行了统计。结果表明行星螺杆对流体运动产生了周期性扰动。初始位置在一起的两个粒子,终点位置却相距很远。示踪粒子的具有对初始敏感的混沌特性,粒子的运动轨迹具有无序性,说明流体存在着混沌效应。

The 3D numerical simulations of the isothermal flow in a embedded planetary screw extruder is carried out by using a finite-volume approach.The boundary conditions of planetary screws were imposed by the user define function（UDF）,through simple physical model to simulate structures of screws.The velocity profiles and pressure distribution in extruder screw channel were obtained;moving path of the fluid and particle distribution law in screw are observed by particle tracking technology;and then the residence time distribution（RTD） in screw was counted.The result revealed that the planetary screws had periodic disturbance on the fluid motion.A pair particle with a closer initial distance are separated from each other in the outlet region.Because the particles have chaotic characteristics and are sensitive to the initial condition,and their moving path are disordered,they prove the existence of chaotic mixing.