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vol. 4, nr. 2 (2004)
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Central and eccentric granular material flows in bins/hoppers registered by DPIV optical technique
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Irena Sielamowicz1, Tomasz A. Kowalewski2, Sławomir Błoński2
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1 Chair of Structural Mechanics, Civil Engineering Department, Białystok Technical University ul. Wiejska 45 E, 15-351 Białystok |
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2 Department of Mechanics and Physics of Fluids, Institute of Fundamental Technological Research, Polish Academy of Sciences, ul. Świętokrzyska 21, 00-049 Warszawa |
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vol. 4 (2004), nr. 2,
pp. 519-531
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abstract:
Application of a new optical technique – Digital Particle Image Velocimetry in investigation of inherently transient processes of granular material flows in a plane model of silo built of Plexiglas is presented. The transparent walls of the model allow for flow visualisation and PIV measurements of velocity fields or local stresses in the material. The outlet in the model was located in three changed positions. Flax-seed as a granular material was used in the experiments. This material develops negligible static electricity when flowing and sliding over Plexiglas. The experimental setup consists of high resolution camera (SensiCam) permitting to acquire about 200 pairs of 1280x1024 pixel images with frequency of 3.75 Hz. Evaluation of grain displacement (and velocity) is performed for each pair of images, taken at the interval 0.267 s. A sequence of digital images of moving material in the model is analyzed with PIV. The zones where the material is in motion and the stagnant zones are characterized. The change of local velocity with time is demonstrated with this method providing an insight into the dynamic behaviour of the granular material. The fluctuations of material motion lead to changes of the wall stresses.
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keywords:
flax-seed, DPIV, eccentric and central flow
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original in:
English
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