{"title":"Quantification of flows in a rectangular channel of a single-screw extruder with a small helix angle based on the energy dissipation rate","authors":"Xuesi Gao, Byungmin Lee, Wook Ryol Hwang","doi":"10.1007/s13367-024-00106-0","DOIUrl":null,"url":null,"abstract":"<div><p>In this work, a systematic approach is proposed for quantifying the effective viscosity, effective shear rate, and screw characteristics of non-Newtonian fluids in an unwound rectangular channel screw flow of a metering zone of the single-screw extruder. The analyses are limited to a small helix angle case (less than 6.7 degrees), where the cross-sectional drag velocity component is small enough. We begin by separating the flow within the channel into two individual flows (the drag-driven flow and the adverse pressure-driven flow). Both the correlations between drag velocity and drag force in the drag flow and between flow rate and pressure buildup in the pressure-driven flow are investigated separately. Then, we propose mixture rules for shear rate and energy dissipation for the combined drag and (adverse) pressure-driven flows in the rectangular channel. The flow quantification approach of the combined flow is established by incorporating the correlations observed in the individual flows with a velocity ratio (the ratio of the drag velocity to the flow rate). The flow quantification method was validated using three non-Newtonian fluids (power law fluid models, a Carreau fluid model, and a regularized Herschel–Bulkley fluid model), through extensive numerical simulations with a 2.5D hybrid scheme. The proposed quantification method can be applied for estimating the relationship between torque, pressure buildup and throughput in the single-screw process with a small helix angle. Theoretical predictions agree well with numerical simulations, with maximum relative errors of 3.3%, and 11% for drag force and pressure buildup, respectively.</p><h3>Graphical abstract</h3>\n<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 1","pages":"67 - 79"},"PeriodicalIF":2.2000,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Korea-Australia Rheology Journal","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s13367-024-00106-0","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 0
Abstract
In this work, a systematic approach is proposed for quantifying the effective viscosity, effective shear rate, and screw characteristics of non-Newtonian fluids in an unwound rectangular channel screw flow of a metering zone of the single-screw extruder. The analyses are limited to a small helix angle case (less than 6.7 degrees), where the cross-sectional drag velocity component is small enough. We begin by separating the flow within the channel into two individual flows (the drag-driven flow and the adverse pressure-driven flow). Both the correlations between drag velocity and drag force in the drag flow and between flow rate and pressure buildup in the pressure-driven flow are investigated separately. Then, we propose mixture rules for shear rate and energy dissipation for the combined drag and (adverse) pressure-driven flows in the rectangular channel. The flow quantification approach of the combined flow is established by incorporating the correlations observed in the individual flows with a velocity ratio (the ratio of the drag velocity to the flow rate). The flow quantification method was validated using three non-Newtonian fluids (power law fluid models, a Carreau fluid model, and a regularized Herschel–Bulkley fluid model), through extensive numerical simulations with a 2.5D hybrid scheme. The proposed quantification method can be applied for estimating the relationship between torque, pressure buildup and throughput in the single-screw process with a small helix angle. Theoretical predictions agree well with numerical simulations, with maximum relative errors of 3.3%, and 11% for drag force and pressure buildup, respectively.
期刊介绍:
The Korea-Australia Rheology Journal is devoted to fundamental and applied research with immediate or potential value in rheology, covering the science of the deformation and flow of materials. Emphases are placed on experimental and numerical advances in the areas of complex fluids. The journal offers insight into characterization and understanding of technologically important materials with a wide range of practical applications.