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Fundamental study on 3D particle tracking, flow stability and particle dynamics relevant to Taylor-Couette reactors

Brockmann, Philipp Maximilian Josef Hermann (2023)
Fundamental study on 3D particle tracking, flow stability and particle dynamics relevant to Taylor-Couette reactors.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00023226
Dissertation, Erstveröffentlichung, Verlagsversion

Kurzbeschreibung (Abstract)

Combining axial and rotational flow between two concentric cylinders, Taylor-Couette Reactors (TCRs) bear huge potential for both mixing and separation of particle laden flows. In such flows, the particle dynamics are affected by the structure of the flow, gravitational and centrifugal forces and interaction of particles with the fluid and themselves. However, these effects are not completely understood on their own such that their combined effect on the particle dynamics in TCRs is far from being predictable. Therefore, in the present thesis, the major physical effects relevant in such scenarios are investigated separately to provide a foundation for future potential applications.

As particle trajectories differ significantly for laminar, bifurcated or turbulent flow, precise knowledge of the flow stability of the carrier liquid is required to set the process parameters. Given that, a comparative study of the linear stability behavior of the laminar flow in a TCR with rotation of the inner cylinder and with rotation of the outer cylinder is performed by means of swirl and curvature parameter. It is revealed that the stability behavior for both the rotating inner as well the rotating outer cylinder case strongly depends on the curvature parameter. While rotation of the inner cylinder generally has a destabilizing effect, it is revealed that rotation of the outer cylinder can stabilize but also destabilize the flow depending on swirl and the curvature parameter.

Until now, the direct observation and characterization of suspensions by means of optical methods bears large potential but is highly challenging especially in small geometries such as in the gap of a TCR. In the present study, different methods are developed to apply Astigmatism Particle Tracking Velocimetry (APTV) on suspension flows for dilute, semi-dilute, mono- and polydisperse suspensions. Using these techniques, the dynamics of mono- and tridisperse suspensions are investigated in pressure driven square duct flows at volume fractions up to 9.1%. It is discovered that interaction of small and large particles can lead to strikingly different concentration patterns in tridisperse compared to monodisperse suspensions depending on Reynolds number, volume fraction and channel height.

While particle interaction is usually associated with higher particle volume fractions, it is known that dilute suspension flows in horizontally aligned rotating cylinders could give rise to formation of band shaped particle accumulations. In this thesis, it is investigated how an additional inner cylinder, which is present in a TCR, affects this band formation. To reduce the complexity, a Taylor Couette flow with solid body rotation without axial flow is considered. Different particle patterns are discovered including three types of bands, which are periodic in axial direction, and two types of bands that are periodic in azimuthal direction. It is shown, that the presence of the inner cylinder can significantly alter the particle trajectories and stabilize the particle bands.

Typ des Eintrags: Dissertation
Erschienen: 2023
Autor(en): Brockmann, Philipp Maximilian Josef Hermann
Art des Eintrags: Erstveröffentlichung
Titel: Fundamental study on 3D particle tracking, flow stability and particle dynamics relevant to Taylor-Couette reactors
Sprache: Englisch
Referenten: Hussong, Prof. Dr. Jeanette ; Egbers, Prof. Dr. Christoph
Publikationsjahr: 2023
Ort: Darmstadt
Kollation: VIII, 302 Seiten
Datum der mündlichen Prüfung: 19 April 2022
DOI: 10.26083/tuprints-00023226
URL / URN: https://tuprints.ulb.tu-darmstadt.de/23226
Kurzbeschreibung (Abstract):

Combining axial and rotational flow between two concentric cylinders, Taylor-Couette Reactors (TCRs) bear huge potential for both mixing and separation of particle laden flows. In such flows, the particle dynamics are affected by the structure of the flow, gravitational and centrifugal forces and interaction of particles with the fluid and themselves. However, these effects are not completely understood on their own such that their combined effect on the particle dynamics in TCRs is far from being predictable. Therefore, in the present thesis, the major physical effects relevant in such scenarios are investigated separately to provide a foundation for future potential applications.

As particle trajectories differ significantly for laminar, bifurcated or turbulent flow, precise knowledge of the flow stability of the carrier liquid is required to set the process parameters. Given that, a comparative study of the linear stability behavior of the laminar flow in a TCR with rotation of the inner cylinder and with rotation of the outer cylinder is performed by means of swirl and curvature parameter. It is revealed that the stability behavior for both the rotating inner as well the rotating outer cylinder case strongly depends on the curvature parameter. While rotation of the inner cylinder generally has a destabilizing effect, it is revealed that rotation of the outer cylinder can stabilize but also destabilize the flow depending on swirl and the curvature parameter.

Until now, the direct observation and characterization of suspensions by means of optical methods bears large potential but is highly challenging especially in small geometries such as in the gap of a TCR. In the present study, different methods are developed to apply Astigmatism Particle Tracking Velocimetry (APTV) on suspension flows for dilute, semi-dilute, mono- and polydisperse suspensions. Using these techniques, the dynamics of mono- and tridisperse suspensions are investigated in pressure driven square duct flows at volume fractions up to 9.1%. It is discovered that interaction of small and large particles can lead to strikingly different concentration patterns in tridisperse compared to monodisperse suspensions depending on Reynolds number, volume fraction and channel height.

While particle interaction is usually associated with higher particle volume fractions, it is known that dilute suspension flows in horizontally aligned rotating cylinders could give rise to formation of band shaped particle accumulations. In this thesis, it is investigated how an additional inner cylinder, which is present in a TCR, affects this band formation. To reduce the complexity, a Taylor Couette flow with solid body rotation without axial flow is considered. Different particle patterns are discovered including three types of bands, which are periodic in axial direction, and two types of bands that are periodic in azimuthal direction. It is shown, that the presence of the inner cylinder can significantly alter the particle trajectories and stabilize the particle bands.

Alternatives oder übersetztes Abstract:
Alternatives AbstractSprache

Taylor-Couette Reaktoren (TCRs) zeichnen sich durch eine Axialströmung mit zusätzlicher Drallkomponente zwischen zwei konzentrischen Zylindern aus und bergen großes Potential für Misch- und Trennprozesse von partikelbeladenen Strömungen. Die Partikeldynamik in solchen Systemen unterliegt dem Einfluss des Strömungszustandes, Gravitations- und Zentrifugalkräften sowie Wechselwirkungen der Partikel untereinander und mit dem Fluid. Jedoch sind diese Effekte nicht vollständig verstanden und die Partikeldynamik in TCRs daher kaum zu antizipieren. In der vorliegenden Arbeit werden die Phänomene daher separat untersucht, um ein Wissensfundament für die gezielte Entwicklung von TCRs zum Mischen und Trennen von Suspensionen zu schaffen.

Da laminare Strömungen Potential für die Partikelfraktionierung haben, während turbulente Strömungen ein Mischen von Partikeln fördern, ist Kenntnis des Strömungszustandes in TCRs Vorrausetzung um die Prozessparameter einzustellen. Es wird daher eine vergleichende Studie des Stabilitätsverhaltens bei rotierendem Außen- und Innenzylinder in Bezug auf Drall und Krümmungsparameter durchgeführt. Dabei zeigt sich, dass das Stabilitätsverhalten bei rotierendem Innen- sowie Außenzylinder stark vom Krümmungsparameter abhängt. Während Rotation des Innenzylinders generell einen destabilisierenden Effekt hat, zeigt sich, dass sich eine Aussenzylinderrotation mit steigendem Drall in Abhängigkeit vom Krümmungsparameter sowohl destabilisierend als auch stabilisierend auf die Strömung auswirken kann.

Die Charakterisierung von Suspensionen mithilfe optischer Messtechniken birgt großes Potenzial, ist jedoch besonders in kleinen Geometrien wie dem Spalt eines TCRs eine große Herausforderung. In dieser Arbeit werden verschiedene Methoden entwickelt um Astigmatismus Particle Tracking Velocimetry (APTV) auf dilute, semi-dilute, mono- und polydisperse Suspensionen anzuwenden. Mithilfe dieser Methoden, wird die Dynamik von mono- und tridispersen Suspension in rechteckigen Kanalströmungen bis zu Volumenfraktionen von 9.1% untersucht. Dabei wird gezeigt, dass die Interaktion von kleinen und großen Partikeln in Abhängigkeit von Reynoldszahl, Volumenfraktion und Kanalhöhe, zu signifikant unterschiedlichen Konzentrationsverteilungen in tridispersen und monodispersen Suspensionen führen kann.

Während Partikelinteraktionen generell bei höheren Volumenfraktionen auftreten, ist bekannt, dass dilute Suspensionen in rotierenden, horizontal ausgerichteten Zylindern bandartige Strukturen ausbilden können. In dieser Arbeit, wird untersucht, wie ein zusätzlicher Innenzylinder, welcher beim TCR vorliegt, diese Strukturbildung beeinflusst. Zur Vereinfachung wird dazu die Strömung bei Festkörperrotation ohne zusätzliche Axialströmung untersucht. Es werden verschiedene Partikelstrukturen entdeckt, darunter auch Bandstrukturen die periodisch in Axialrichtung aber auch welche die periodisch in Azimutalrichtung sind. Es wird gezeigt, dass der Innenzylinder die Partikeltrajektorien beeinflussen und zu einer Stabilisierung der Bandstrukturen beitragen kann.

Deutsch
Freie Schlagworte: Particle Tracking, Linear Stability Analysis, Spiral Poiseuille Flow, Particle Migration, Astigmatism Particle Tracking, Particle Banding, Particle Band Formation, Taylor-Couette Reactor, Taylor-Couette Flow, Inertial Migration, Shear Induced Migration, 3D Particle Tracking, Particle Separation, Particle Sorting, Centrifugal Instabilities, Tollmien-Schlichting Instabilities, Flow Transition, Polydisperse Suspension Flows, Semi-Dilute Suspensions, Monodisperse Suspensions
Status: Verlagsversion
URN: urn:nbn:de:tuda-tuprints-232265
Sachgruppe der Dewey Dezimalklassifikatin (DDC): 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau
Fachbereich(e)/-gebiet(e): 16 Fachbereich Maschinenbau
16 Fachbereich Maschinenbau > Fachgebiet Strömungslehre und Aerodynamik (SLA)
Hinterlegungsdatum: 16 Feb 2023 13:10
Letzte Änderung: 17 Feb 2023 07:39
PPN:
Referenten: Hussong, Prof. Dr. Jeanette ; Egbers, Prof. Dr. Christoph
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: 19 April 2022
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