Dedicated vertical wind tunnel for the study of sedimentation of non-spherical particles

Bagheri, Gholamhossein (Section of Earth and Enviornmnetal Sciences, University oF Geneva, Geneva, Switzerland) ; Bonadonna, Costanza (Section of Earth and Enviornmnetal Sciences, University oF Geneva, Geneva, Switzerland) ; Manzella, Irene (Section of Earth and Enviornmnetal Sciences, University oF Geneva, Geneva, Switzerland) ; Pontelandolfo, Piero (School of Engineering, Architecture and Landscape (hepia), HES-SO // University of Applied Sciences Western Switzerland) ; Haas, Patrick (School of Engineering, Architecture and Landscape (hepia), HES-SO // University of Applied Sciences Western Switzerland)

A dedicated 4-m-high vertical wind tunnel has been designed and constructed at the University of Geneva in collaboration with the Groupe de compétence en mécanique des fluides et procédés énergétiques. With its diverging test section, the tunnel is designed to study the aero-dynamical behavior of non-spherical particles with terminal velocities between 5 and 27 ms−1. A particle tracking velocimetry (PTV) code is developed to calculate drag coefficient of particles in standard conditions based on the real projected area of the particles. Results of our wind tunnel and PTV code are validated by comparing drag coefficient of smooth spherical particles and cylindrical particles to existing literature. Experiments are repeatable with average relative standard deviation of 1.7%. Our preliminary experiments on the effect of particle to fluid density ratio on drag coefficient of cylindrical particles show that the drag coefficient of freely suspended particles in air is lower than those measured in water or in horizontal wind tunnels. It is found that increasing aspect ratio of cylindrical particles reduces their secondary motions and they tend to be suspended with their maximum area normal to the airflow. The use of the vertical wind tunnel in combination with the PTV code provides a reliable and precise instrument for measuring drag coefficient of freely moving particles of various shapes. Our ultimate goal is the study of sedimentation and aggregation of volcanic particles (density between 500 and 2700 kgm−3) but the wind tunnel can be used in a wide range of applications.


Keywords:
Article Type:
scientifique
Faculty:
Ingénierie et Architecture
School:
HEPIA - Genève
Institute:
inSTI - Institut des Sciences et Technologies industrielles
Date:
2013-05
Pagination:
12 p.
Published in:
Review of Scientific Instruments
Numeration (vol. no.):
2013, vol. 84, article no. 054501
DOI:
ISSN:
0034-6748
Appears in Collection:

Note: The status of this file is: restricted


 Record created 2020-05-29, last modified 2020-05-29

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