往复副螺棱高度对单螺杆挤出机内混合行为的影响

Effect of the Reciprocating Baffle Height on Mixing Performance in Single Screw Extruder

建立了带有扰动副螺棱的单螺杆均化段数学模型,探讨了不同副螺棱高度对混合的影响。将有限体积方法与叠加网格技术相结合,得到了螺槽内牛顿流体三维等温周期性速度场。采用4阶Runge-Kutta方法进行流体前锋追踪计算,得到了粒子群及示踪剂界面混合行为。Poincaré截面揭示了混沌混合在螺槽横截面内呈现"8"字形带状分布,内外分别被准周期运动区域填充。副螺棱高度越大,混沌混合区域所覆盖的尺度越大,混合能力越好。

The effect of the moving baffle height on the mixing kinematics of the screw channel was investigated. A model with the baffle lower than the screw channel, as well as the corresponding mathematical model, was developed. The periodic flow and mixing performance of Newtonian fluid in the metering zone of such an extruder were numerically simulated. The finite volume method was used and the flow domain was meshed by staggered grids with the periodic boundary conditions of the barrier motion being imposed by the mesh supposition technique. Fluid front tracking was carried out by a fourth-order Runge-Kutta scheme. The growth of the interface stretch of tracers with time and particles mixing performance were also obtained. Poincare sections were applied to reveal the geometrical scale of chaotic mixing patterns, which describe the typical Figure ＂8＂ shape in the cross-section view of the flow channel, as well as the regions with embedded regular laminar flows. The larger the baffle height is, the larger the scale of the chaotic mixing is, and the more intensive the mixing ability is.