A comparative study on optical techniques for the estimation of granular flow velocities

Hagemeier, Thomas; Börner, Matthias; Bück, Andreas; Tsotsas, Evangelos

doi:10.1016/j.ces.2015.03.045

Cited by 41 publications

(13 citation statements)

References 80 publications

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“…There are many techniques for the non-invasive measurements of granular flow velocities [21][22][23][24][25][26][27][28][29], including Particle Image/Tracking Velocimetry (PIV/ PTV), Laser Doppler velocimetry (LDV), Laser Speckle velocimetry (LSV) and other tomographic methods like Positron Emission Particle Tracking (PEPT) or Magnetic Resonance Imaging (MRI). Among them PIV/ PTV is the most widely used one for the dense granular flow velocity measurement [21][22][23][24]. However, PTV requires that each particle can be distinguished clearly which puts huge demand on image resolution and more importantly computing power.…”

Section: Introductionmentioning

confidence: 99%

“…While in case of PIV there is no requirement to distinguish each particle, large signal-to-noise of recorded images is desirable requiring for example uniform illumination, which is difficult to obtain due to complex interaction of imaging and lighting system with the observed granular flow, and accompanying experimental set-up [20]. LDV is another widely used method for the measurement of solid or fluid velocities with tracer particles [21]. Once again due to high concentration of the particles and resulting strong light scattering it is not suitable for the dense granular flow with only occasional applications.…”

Section: Introductionmentioning

confidence: 99%

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Velocities of irregular particles in a continuously avalanching surface flow within a rotating drum

Lin

Yang

et al. 2018

Powder Technology

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Velocity of irregular particles is difficult to measure and analyze due to their irregular shape. A method of spatial filtering velocimetry is used to measure the velocity of particles on the surface of the rotating drum in the rolling mode. The image of the particle flow also shows that the surface is not a straight line but mound exists due to the accumulation of particles at the middle of the drum which influence the velocity profile. The variation of the velocity distribution of irregular particles with drum speeds, particle sizes, and drum diameters is presented and discussed in the paper. The results indicate that there were two velocity peaks in the velocity profile of irregular glass sand at a relatively lower rotating speed. Furthermore, with the increase of the drum speed, the middle valley in the profile gradually moves to the upper right and merges with the second velocity peak and there is only one peak in the velocity profile along streamwise direction of the bed surface consequently similar to spherical particles velocity profile.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Velocities of irregular particles in a continuously avalanching surface flow within a rotating drum

Lin

Yang

et al. 2018

Powder Technology

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“…Fiber‐optical probes were originally developed in the 1970s and 1980s to measure the velocity of particles in dense multiphase flows . The probe setup consists of a light source and an array of fiber optics to capture the optical image of the particles.…”

Section: Introductionmentioning

confidence: 99%

Investigations on the Capability of the Statistical Extinction Method for the Determination of Mean Particle Sizes in Concentrated Particle Systems

Schwarz

Ripperger

Antonyuk

2018

Part & Part Syst Charact

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Due to the fast growing number of processes involving particulate systems, simple and robust measurement techniques which enable an inline monitoring of the particle size and their concentration are urgently required, since this ensures control but also process optimization. In this work, an inline measurement technique based on the statistical extinction method is developed that provides a process monitoring for a wide range of particulate processes, such as dispersion processes and spray processes. The method allows the determination of the mean size and concentration for particle systems with the size larger than 1 µm. For this purpose, a light beam illuminates the particle system, whereby the fluctuating light intensity due to the particle movement through the light beam is detected. The statistical fluctuation of the signal can be related to a mean particle size and a particle concentration. Since concentrated particle systems cause effects that additionally influence the signal, such as multiple scattering, approaches are needed to reduce or eliminate these effects. In this work, an approach using a spatial frequency filter is applied. The experimental investigations reveal that the effects can be significantly reduced with the spatial frequency filter.

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“…Due to the existence of light source, PIV and LDV methods can only be applied to transparent fluidized beds, or fluidized beds with glass windows. Besides, velocity measurement can be carried out only on the front-layer particles [37] for LDV method. The optical fiber probe is intrusive, and therefore interferes to some extent with the flow field being measured.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Monitoring of particle motions in gas-solid fluidized beds by electrostatic sensors

Yang

Zhang

et al. 2017

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P TACCEPTED MANUSCRIPT Electrostatic charge signals in the fluidized bed contain much dynamic information on particle motions, which are poorly understood and explored. In this work, correlation velocities of Geldart B and D particles were measured, analyzed and compared by induced electrostatic sensors combined with cross-correlation method in the fluidized bed. The results indicated that the average correlation velocity of particle clouds increased and the normalized probability density distributions of correlation velocities broadened when the superficial gas velocity increased in the dense-phase region. Both upward and downward correlation velocities could be acquired in the dynamic bed level region. Under the same excess gas velocity, the average correlation velocity of Geldart D particles was significantly smaller than that of Geldart B particles, which was caused by the smaller bubble sizes caused by the dominant bubble split over coalescence and less volume of A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 gas forming bubbles for Geldart D particles. The experimental results verified the reliability and repeatability of particle correlation velocity measurement by induced electrostatic sensors in the gas-solid fluidized bed, which provides definite potential in monitoring of particle motions.

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A comparative study on optical techniques for the estimation of granular flow velocities

Cited by 41 publications

References 80 publications

Velocities of irregular particles in a continuously avalanching surface flow within a rotating drum

Velocities of irregular particles in a continuously avalanching surface flow within a rotating drum

Investigations on the Capability of the Statistical Extinction Method for the Determination of Mean Particle Sizes in Concentrated Particle Systems

Monitoring of particle motions in gas-solid fluidized beds by electrostatic sensors

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