以三維有限元素法對共押出進料區塊之非等溫流動模擬

Abstract

本文旨在使用Bird-Carreau 泛牛頓流體模型進行雙層共押出進料區塊內流動之三維有限元素模擬，探討共押出製程中之界面包覆及界面不穩定現象，並在進料區塊壁面邊界採取滑動邊界設定。由模擬結果可看出在等溫系統下，忽略高分子流體因摩擦所產生之黏滯熱，所以包覆現象與非等溫系統下之模擬結果不同。藉由改變黏度比、流量比、上下層流體入口溫度及壁面溫度來探討對包覆現象之影響。經由與Giesekus黏彈模型比較，高分子之二次流動行為才是造成包覆現象之主要因素。

In this study, non-isothermal flow simulation of bicomponent coextrusion feedblock with Bird-Carreau model and slip boundary condition imposed at the polymer/polymer/wall contact line were investigated. The simulation results showed that the encapsulation phenomena under non-isothermal condition is different from that under isothermal condition. This is due to the fact that isothermal condition neglects the effect of viscous heating. In the studies, with regards to the bicomponent system, the effect of various viscosity ratio, flow rate ratio, and the respective inlet temperature and the respective contacting wall temperature of each component on the encapsulation phenomena were investigated. Secondary flow phenomena was found to be a major factor for the encapsulation phenomena by comparison of Bird-Carreau model with Giesekus model.