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

在工业优势高分子材料的熔融过程中，其流动和传热场中存在的几种特征行为取决于其非牛顿性质和非线性温度依赖关系。在材料加工过程中，这些流动和传热行为对于保持和控制工程质量和速度变得越来越重要。为了模拟热流现象，采用多种方法对聚合物熔体流动进行了实验研究，得到了聚合物熔体的时变流动和换热特性及其非定常效应。本文采用可视化图像分析和多点非定常测量的方法，对聚合物熔体前沿的非定常流动和换热现象进行了实验研究。为了利用高速视频系统从连续图像中清晰热流体三维现象，研究了对整个流动和换热场有重要影响的气液界面的非定常地理形状和融锋区域的速度矢量场。通过不同位置间的相互关系，数值分析了界面上形状构型的非定常效率和局部效率，以检测过渡现象。将高分子材料（PP）放入有许多实心原短条的圆柱形管中，通过电加热器改变管中物料在运输过程中的相向。熔融液由可控步进电机驱动的活塞从喷嘴推出到玻璃管（试验段：各种型号）中。管的表面设置了正常条件和人工条件，并用薄层硅油进行比较。将出口速度条件改为被推活塞的运动速度，以明确其作用。从实验结果中，我们发现了以下几个有趣的现象：气液界面的形状特性随时间变化，通过局部组态分析检测到两种现象的双向转换，即一种是从中心到壁面（喷泉流），另一种是从近壁面通过非均匀滑动现象从近壁面到中心。熔锋的传热也发生了变化，并与上述现象相关。这些现象源于高聚物的性质，因此有必要在数值模拟上建立传热机理模型。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