Flow and Heat Transfer Characteristics of High-Polymer Flow with Free Gas-Liquid Interface Boundary

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In the melting and continuous phase changing of the high-polymer material on industrial applications (injection molding and etc.), there are several characteristic behaviors in the flow field and heat transfer field in depends on its non-newtonian properties and non-liner temperature dependencies. These flow and heat behaviors become more important recently to keep and control engineering quality in the material proctessing. The difficulty of the experimental investigation of the melting high-polymer is mainly that there is no appropriate experimental method to measure the unsteady flow and heat transfer field simultaneously with high accuracy that can detect the time-special non-newtonian properties and its unsteady effects.In this study, the unsteady flow and heat transfer phenomena in melt-front of high-polymer fluid with free gas-liquid interface boundary will be shown experimentally with a numerical tomography by visualization images and multi-point unsteady measurements. The unst … More eady geographic shape of the gas-liquid interface and velocity vector field in melt-front which make important effects on whole heat and transfer field, are detected from the continuos images by video, and heat transfer from fluid into wall detected by the heat transfer sensors. The pre-experiments using liquid high-polymer (PEO) with a room temperature were done at first for checking methods, and then several experimental trials have done with mostly same conditions as real engineering material processing. The high-polymer materials (PP) were put into the cylindrical tube with many solid original short bars. In the tube, as the temperature raise over melting point of material by electric heaters and frictional heat generation, the material change its phase aspect in transit. The melting fluid with the effects of surface tension gets pushed out into the tube and rectangular channel from the nozzle by a piston moved with controllable stepping motor. The velocity conditions at exit are changed as the moving velocity of pushed piston for making clear its effects. The continuous 3-D shape and reattachment of the melt-front are detected experimentally with the multi-image processing by CCD video Camera. And the flow field in the melt-front would be tried to detect as velocity vector and shear stress components from two images separated with the time.From experimental results, several interesting phenomena were detected as below. The gas-liquid interface changes its shape properties time-dependently with velocity fluctuations on vector-map near wall, which mean that there are several local and non-uniform slipping phenomena at molecular levels. Heat transfers in melt-front are also changed and correlated with the phenomena. These phenomena originated in high-polymer properties can be made useful of building the heat transfer mechanism models in order to make clear the all phenomena and to estimate the whole process of melting with a numerical simulation. Less