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ISBN 9783843936149

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978-3-8439-3614-9, Reihe Strömungsmechanik

Maximilian Fischer
Numerical investigation of the Segré-Silberberg effect and its application in particle classification

101 Seiten, Dissertation Technische Universität Dortmund (2017), Softcover, A4

Zusammenfassung / Abstract

In mechanical process engineering, the commonly applied methods for particle classification are based on sedimentation or filtration. A small density difference between particles and carrier fluid or a high viscosity of the carrier fluid impairs the efficiency of these methods. The present work deals with the investigation of a novel method for particle classification that does not require a density difference between particles and carrier fluid and is well suited for highly viscous carrier fluids. The separation principle of this method is based on the Segré-Silberberg effect. This effect leads to the accumulation of solid particles on a specific radial equilibrium position in laminar tube flows, whereby this radial position depends on the particle size. Matulka (2013) successfully applied the classification method using an experimental setup consisting of a separation tube, in which the particles migrate to their radial equilibrium position, and a downstream expansion of the flow, where the particles are graded by splitting the flow. This work focuses on quantifying the effect of the particle size and the Reynolds number on the behavior of neutrally-buoyant, spherical particles in laminar flow. Specifically, the radial equilibrium positions and particle trajectories in tube flows and the particle motion inside the flow expansion of the classification device used by Matulka (2013) are investigated using numerical methods. The simulations are performed for tube Reynolds numbers in the range of 5 ≤ Re ≤ 100 and particle diameters in the range of 0.1 to 0.5 times the pipe diameter. The obtained equilibrium positions and trajectories are in good agreement with the results of previous experimental and numerical investigations. Regarding its application in particle classification, the simulations show that a classification device should be operated at large tube Reynolds numbers due to a greater radial offset between particles and a faster positioning under these flow conditions.