Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part B. (Superimposed Drag-Pressure Flows in Extrusion)

Abstract

Due to progress in the development of screw designs over recent decades, numerous high-performance screws have become commercially available in single-screw extrusion. While some of these advanced designs have been studied intensively, others have received comparatively less attention. We developed and validated a semi-numerical network-theory-based modeling approach to predicting flows of shear-thinning polymer melts in wave-dispersion screws. In the first part (Part A), we systematically reduced the complexity of the flow analysis by omitting the influence of the screw rotation on the conveying behavior of the wave zone. In this part (Part B), we extended the original theory by considering the drag flow imposed by the screw. Two- and three-dimensional melt-conveying models were combined to predict locally the conveying characteristics of the wave channels in a discretized flow network. Extensive experiments were performed on a laboratory single-screw extruder, using various barrel designs and wave-dispersion screws. The predictions of our semi-numerical modeling approach for the axial pressure profile along the wave-dispersion zone accurately reproduce the experimental data. Removing the need for time-consuming numerical simulations, this modeling approach enables fast analyses of the conveying behavior of wave-dispersion zones, thereby offering a useful tool for design and optimization studies and process troubleshooting.

Melt Conveying in Single-Screw Extruders: Modeling and Simulation

“…While existing equations were mainly designed to estimate the flow rate and viscous dissipation, further attention must be directed towards parameters such as the power consumption, temperature development, and mixing capability. Recent studies have demonstrated how analytical approximations constructed for screw channels of constant geometry can be implemented into a network-based approach to model the axial pressure and temperature development of both conventional and high-performance screws [ 140 , 142 , 164 ]. The development of new approximation methods will be promoted by the advent of data-based modeling and artificial intelligence.…”

“…To provide melt-conveying models that are continuous across their full application range, we have recently proposed a hybrid modeling approach [ 133 ]. The novelty of our method lies in the construction of analytical approximation equations from a large number of numerical solutions to scaled flow equations by using symbolic regression based on genetic programming.…”

“…Similar to the previous approach, the range of the dimensionless down-channel pressure gradients was adjusted as a function of the power-law index. The validity of the two- and three-dimensional melt-conveying models was tested against experimental extrusion data measured for both standard and high-performance screws [ 140 , 141 , 142 ]. Recently, the usefulness of the symbolic regression analysis was analyzed in a comparative study that investigated various data-based modeling approaches [ 143 ].…”

Nghiên Cứu Dòng Chảy Của Nhựa Nóng Chảy Trong Thiết Bị Đùn Trục Vít Đơn

“…Gần đây, Christian Marschik và các đồng nghiệp cũng dùng lý thuyết lưu chất Newton để thực hiện nghiên cứu của họ. Công bố của họ được chia làm 2 phần, phần A [8] là những nghiên cứu sâu về lý thuyết dòng chảy để làm giảm độ phúc tạp của mô hình toán, phần B [9] trình bày những phát triển mới về dòng chảy kéo trong máy đùn trục vít đơn. Thông số đầu vào quan trọng của họ là đường kính của trục vít, 35 mm, kết quả đầu ra là các phương trình mô tả dòng chảy lưu chất, khó ứng dụng vào thực tế.…”

Leakage-Flow Models for Screw Extruders

“…In the construction of the leakage-flow models, particular attention was paid to their usability in our screw-simulation routine for predicting the conveying behavior of melt-conveying zones. For detailed information, the reader is referred to the following articles and PhD-theses: Aigner [36], Marschik et al [37][38][39], Roland et al [40], and Luger [41].…”