Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part A (Pressure Flows)
Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part A (Pressure Flows)
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DOI：
10.3390/polym11091488
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发表时间：
2019-09-01
期刊：
影响因子：
5
通讯作者：
Steinbichler, Georg
中科院分区：
文献类型：
--
作者：
Marschik, Christian;Doerner, Marius;Steinbichler, Georg
波分散螺杆已在工业上用于许多类型的挤出工艺、注塑和吹塑。这些高性能螺杆是通过用熔体输送区代替传统螺杆的计量部分而构造的，熔体输送区由两个或更多个平行的流动通道组成，所述流动通道在多个循环中周期性地深入振荡。在螺杆通道之间的屏障螺纹被选择性地底切的情况下，熔融树脂策略性地被迫流过第二螺纹，确保聚合物熔体的重复的跨通道混合。尽管与工业相关，但很少有科学研究详细研究波浪分散段中的流动。因此，目前的螺杆设计往往是基于传统的试错程序，而不是挤出理论的原则。这项研究分为两个部分，旨在系统地解决这一问题。这里报告的研究（A部分）旨在降低问题的复杂性，专门分析波截面中聚合物熔体的压力诱导流动。忽略螺旋旋转对波段输送特性的影响，结果可以清楚地归属于流动机制的控制类型，从而提供对基础物理的更好理解。对一种新型的具有交替通道深度分布的双波纹通道挤出模头进行了实验研究。提出了一种基于网络理论的数值模拟方法，该方法局部地描述了沿波道沿着的下游和横向流动，并精确地预测了流域中的压力分布。此外，我们的数值方法的解决方案进行了比较，三维非牛顿CFD模拟的结果。本研究的结果将扩展到B部分中的真实的螺杆设计，其中将包括流量分析中螺杆旋转的影响。
Wave-dispersion screws have been used industrially in many types of extrusion processes, injection molding, and blow molding. These high-performance screws are constructed by replacing the metering section of a conventional screw with a melt-conveying zone consisting of two or more parallel flow channels that oscillate periodically in-depth over multiple cycles. With the barrier flight between the screw channels being selectively undercut, the molten resin is strategically forced to flow across the secondary flight, assuring repeated cross-channel mixing of the polymer melt. Despite the industrial relevance, very few scientific studies have investigated the flow in wave-dispersion sections in detail. As a result, current screw designs are often based on traditional trial-and-error procedures rather than on the principles of extrusion theory. This study, which was split into two parts, was carried out to systematically address this issue. The research reported here (Part A) was designed to reduce the complexity of the problem, exclusively analyzing the pressure-induced flows of polymer melts in wave sections. Ignoring the influence of the screw rotation on the conveying characteristics of the wave section, the results could be clearly assigned to the governing type of flow mechanism, thereby providing a better understanding of the underlying physics. Experimental studies were performed on a novel extrusion die equipped with a dual wave-channel system with alternating channel depth profiles. A seminumerical modeling approach based on network theory is proposed that locally describes the downchannel and cross-channel flows along the wave channels and accurately predicts the pressure distributions in the flow domain. The solutions of our seminumerical approach were, moreover, compared to the results of three-dimensional non-Newtonian CFD simulations. The results of this study will be extended to real screw designs in Part B, which will include the influence of the screw rotation in the flow analysis.