Dreidimensionale Simulation und Visualisierung von Strömungs- und Mischprozessen im Doppelschneckenextruder

The mixing behaviour of new material systems (PES/glass- and PP/metal-blends) is studied in dependence of the process parameters screw-speed, material type and non-polymer rate in the present dissertation. The glass and the metal are low melting materials and they are processed in a fluid state. The work is focused on a small mixing zone, consisting of two kneading elements in a co-rotating twin screw extruder. It is shown by the analysis that the correlations between process parameters and development of morphology parameters (particle diameter, number of particles) in the mixing zone could be provided evidently. The correlations are described by twenty-five models, which have medium up to high coefficients of determination. Furthermore the fluid flow in the mixing zone is studied by three-dimensional FEA-simulations. The influence of a process parameter change on fluid-mechanical parameters (e.g. residence time, rate of deformation) is analysed. A change of the screw speed shows a highly influence on the parameters, while a variation of material density and flow rate has no significant effect on the fluid-mechanical parameters. A method for the development of regression models is developed by combination of mathematical analysis (correlation, regression and variance) in the present work. The functional correlations between fluid-mechanical parameters and the change of morphology parameters in the mixing zone are determined by this method. The models are tested on their reliability and also they could be rated by the method. Therefore the criteria accuracy, simpleness and plausibility are applied. The method is used to determine the correlations between fluid-mechanical parameters and morphology parameters. It shows that the parameters particle diameter, standard deviation of the diameter distribution and number of particles before the mixing zone, disperse phase ratio, viscosity ratio, collision frequency and capillary number are adequate for the description of the morphology change. The generalisation of the parameter effects on the processes dispersion and coalescence is attempted. The parameters residence time, mixing index and entropy proved to be not adequate for the description of morphology change. The application of the parameter rate of deformation is problematic, because the number of dispersion and coalescence processes increase with an increasing rate of deformation. The differences between the processing behaviour of PES/glass- and PP/metal-blends are causally determined by the difference of the particle diameters before the mixing zone and the different viscosity ratios of the blends. Furthermore a new visualisation method for simulation data of flow- and mixing-processes in the extruder is developed with the assistance of Virtual Reality (VR) techniques. Thereby the Virtual Reality techniques are utilised for an analysis of the compounding processes in plastics processing.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2008

Author dc:creator

• Stewering, Jörn

Contributors dc:contributor

• Haberstroh, Edmund

• info:eu-repo/classification/ddc/620
• Numerische Strömungssimulation
• Kunststoffverarbeitung
• Extrudieren
• Visualisierung
• Mischen
• Prozessentwicklung <Technik>
• Modellierung
• Virtuelle Realität
• Ingenieurwissenschaften
• numerical simulation
• plastics processing
• extrusion
• mixing
• visualisation

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-112870%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A50321