Unsteady Heat Transfer and Fluid Mechanism at Melt-Front Region with Injection Molding with High Polymer Materials

在高分子材料的熔融加工过程中，由于其非牛顿特性和非线性温度依赖性，在流动和传热领域存在着几种特征行为。这些流动和传热行为对保持和控制材料加工的工程质量和速度变得越来越重要。为了模拟高分子熔体流动的热-流现象，本文采用多种测量方法对高分子熔体流动进行了实验研究，获得了高分子熔体前沿的非稳态流动与传热特性及其非稳态效应，并通过可视化图像分析和多点非稳态测量，对高分子熔体前沿的非稳态流动与传热现象进行了实验研究。确定了对整个流动和传热场有重要影响的气液界面非稳态几何形状和熔体前沿区速度矢量场 关于我们 为从高速摄像系统拍摄的连续图像中清晰地显示热流三维现象而设计。为了检测过渡现象，采用互相关法对界面形状的非稳态效率和局部效率进行了数值分析，将高分子材料（PP）放入带有许多实心原始短棒的圆柱形管道中，在管道中，材料在电加热器的作用下改变其相态。通过可控步进电机移动的活塞将熔融流体从喷嘴推入玻璃管（测试部分：各种类型）。管表面设置正常和人工条件下，与薄层硅油进行比较。为了研究活塞的运动速度对出口速度的影响，我们改变了出口处的速度条件。气液界面的形状随时间变化，局部位形分析发现了气液界面的双向转变现象，即从中心到壁面（喷泉流）和近壁面非均匀滑移现象导致的从近壁面到中心的双向转变。熔体前沿的传热也发生了变化，并与上述现象相关。这些现象源于高分子材料的特性，需要建立数值模拟的传热机理模型。少

In the melting process of high-polymer materials on the industrial advantage, there are several characteristic behaviors in the flow and heat transfer field in depends on its non-newtonian properties and non-liner temperature dependencies. These flow and heat transfer behaviors become more important recently to keep and control engineering quality and speed in the material processing. For the modeling of heat-fluid phenomena, the experimental investigation of the melting high-polymer flow has been done with various method measurements for getting the time-special flow and heat transfer properties and its unsteady effects.In this study, the unsteady flow and heat transfer phenomena in melt-front of high-polymer are shown experimentally with visualization images analysis and multi-point unsteady measurements. The unsteady geographic shape of the gas-liquid interface and velocity vector field in melt-front region, which make important effects on whole flow and heat transfer field, are det … More ected for making clear the heat-fluid 3-D phenomena from the continuous images by high-speed video system. The unsteady and local efficiencies of the shape configuration on interface are analyzed numerically by cross-correlation between various positions for the detection of the transitional phenomena.The high-polymer materials ( PP ) are put into the cylindrical tube with many solid original short bars, hi the tube, flie material changes its phase aspect in transit by electric heaters. The melting fluid gets pushed out into the glass tube ( test section: various types ) from the nozzle by a piston moved with controllable stepping motor. The surfaces of tube are set normal and artificial conditions with thin-layer of silicon oil for comparison. The velocity conditions at exit are changed as the moving velocity of pushed piston for making clear its effects.From experimental results, several interesting phenomena were detected as below. The gas-liquid interface changes its shape properties time-dependently, and the two-way transitions of phenomena are detected with the local configuration analysis, which mean that one is from the center to wall ( fountain flow ), another is from near-wall to center by non-uniform slipping phenomena near-wall. Heat transfers in melt-front are also changed and correlated with the above phenomena. These phenomena originated in high-polymer properties can be made needful of building the heat transfer mechanism models on numerical simulations. Less