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1

Application of particle image velocimetry method for monitoring the volume changes during silo flow on the basis of X-radiographs

Grudzień K., Niedostatkiewicz M., Babout L., Adrien J.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2010

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T. 14, z. 3/2

695-710

EN

Particle Image Velocimetry (PIV) technique, as an optical method of flow visualisation, is based on the numerical analysis of successive pairs of digital photographs (CCD camera). It is typically used to obtain the time dependent field of velocity distributions of flowing material. In case of silo flow PIV methods allows to analyse of the volumetric strain in sand during silo discharging process. Monitoring of granular materials volumetric strain in silos is crucial for construction site safety. Authors are presenting application of PIV method for analysis of a bulk solid deformation during silo emptying to images obtained using X-ray, continuous exposure based radiographs. Analysis of radiograph images enables to gather the additional information, comparing to classical input data for PIV-digital photographs, about the volume changes, especially in the core of flow and above the outlet. Results are presented as volumetric strain changes for selected time points of the silo emptying process.

PL

Anemometria obrazowa PIV (Particle Image Velocimetry), stosowana jak metoda wizualizacji przepływów oparta jest na numerycznej analizie kolejnych par obrazów cyfrowych pochodzących z kamery CCD. Zastosowanie tej techniki pozwala wyznaczyć rozkład prędkości przepływającego materiału. W przypadku zastosowania PIV do analizy przepływu silosowego możliwe jest wyznaczenie odkształceń objętościowych w materiale sypkim podczas rozładunku silosu. Monitorowanie zmian objętościowych w materiałach sypkich jest krytyczne dla bezpieczeństwa konstrukcji silosu. W artykule autorzy prezentują zastosowanie techniki PIV do analizy zmian objętościowych materiałów sypkich w trakcie opróżniania prostokątnego modelu silosu. Technika PIV zastosowana została do przetwarzania radiogramów pochodzących z systemu tomografii promieni X. Analiza radiogramów pozwala na zebranie dodatkowych informacji, w porównaniu z analizą zdjęć cyfrowych z kamery CCD, o zmianach objętościowych w rdzeniu przepływu i powyżej wylotu silosu. Wyniki przedstawiane zostały jako zmiany objętościowe dla wybranych chwil czasu opróżniania silosu.

2

Deformation measurements in granular bodies using a Particle Image Velocimetry technique

Słomiński C., Niedostatkiewicz M., Tejchman J.

Archives of Hydro-Engineering and Environmental Mechanics

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2006

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Vol. 53, nr 1

71-94

EN

The paper presents results of strain measurements in cohesionless sand in two different boundary value problems, namely quasi-static pull-out test of a steel wall and confined granular flow in a rectangular model silo using a non-destructive method called Particle Image Velocimetry (PIV) which is a technique for measuring surface displacements from digital images. Advantages and disadvantages of the method are outlined.

3

FE-simulations of rapid silo flow with a polar elasto-plastic constitutive model

Tejchman J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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1998

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Vol. 2, No 3

473-501

EN

The paper presents results on numerical modelling of rapid flow of granular materials in a model silo with convergent smooth walls. The calculations were performed with a finite element method based on a polar elasto-plastic constitutive relation by Muhlhaus (1995). The relation differs from the conventional theory of plasticity by the presence of Cosserat rotations and couple stresses using a mean grain diameter as a characteristic length. The characteristic length causes that numerical results do not depend upon the mesh discretisation. The model tests on rapid silo flow of glass beads performed by Renner in a glass hopper with a large wall inclination from the bottom were numerically simulated. The plane strain FE-calculations were performed by taking into account inertial forces and linear viscous damping. A satisfactory agreement between numerical and experimental results was obtained. Advantages and limitations of a continuum approach for simulations of rapid silo flow were outlined.