Developing Tracer Particles for X-Ray Particle Tracking Velocimetry

X-ray imaging, as a noninvasive flow visualization technique, has been shown to be a useful method for observing and characterizing multiphase flows. One type of X-ray flow visualization technique, called X-ray Particle Tracking Velocimetry (XPTV), tracks an X-ray attenuating particle in an opaque fluid flow. A significant challenge with XPTV is identifying tracer particles with the desired fluid flow characteristics (e.g., small and neutrally buoyant) but yet differentially attenuate X-rays, which is based primarily on density differences. This paper describes the manufacturing of XPTV tracer particles that satisfy specific particle characteristics including high X-ray attenuation, uniform shape, specified effective density, and desired diameter. An example use of these particles as an intruder particle in a fluidized bed (to simulate biomass injection) is then demonstrated using X-ray stereographic imaging to determine intruder particle position as a function of time in a three-dimensional opaque system.

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Developing X-Ray Particle Tracking Velocimetry for Applications in Fluidized Beds

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C ◽

10.1115/imece2008-66224 ◽

2008 ◽

Cited By ~ 4

Author(s):

Joshua B. Drake ◽

Nathan P. Franka ◽

Theodore J. Heindel

Keyword(s):

Fluidized Bed ◽

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Fluidized Beds ◽

Tracer Particle ◽

Scale Up ◽

Solid Particles ◽

X Rays ◽

X Ray ◽

High Heat Transfer

Fluidized beds utilize a gas stream to fluidize solid particles and are used in the process industries because they provide a low pressure drop, uniform temperature distribution, and high heat transfer rates. Knowledge of fluidized bed hydrodynamics is necessary in the design and scale up of such devices. However, fluidized bed hydrodynamics are difficult to visualize and quantify because the systems are opaque and intrusive probes do not provide satisfactory measurements. This paper describes the development of X-ray particle tracking velocimetry (XPTV) to study fluidized bed hydrodynamics. XPTV utilizes X-rays to track specially designed tracer particles in a fluidized bed to noninvasively determine particle velocities. Stereoscopic X-ray imaging is used to locate the 3D position of the tracer particle as a function of time within a fluidized bed, from which particle velocity can be determined. An example of particle tracking will be shown and the automation of this process will be described.

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Tomographic X-ray particle tracking velocimetry

Experiments in Fluids ◽

10.1007/s00348-021-03362-w ◽

2021 ◽

Vol 63 (1) ◽

Author(s):

Simo A. Mäkiharju ◽

Jan Dewanckele ◽

Marijn Boone ◽

Christian Wagner ◽

Andreas Griesser

Keyword(s):

Porous Media ◽

Liquid Film ◽

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Signal To Noise Ratio ◽

Time Step ◽

Taylor Bubble ◽

X Ray ◽

Tracer Particles ◽

Scan Speed

Abstract We investigate the feasibility of in-laboratory tomographic X-ray particle tracking velocimetry (TXPTV) and consider creeping flows with nearly density matched flow tracers. Specifically, in these proof-of-concept experiments we examined a Poiseuille flow, flow through porous media and a multiphase flow with a Taylor bubble. For a full 360$$^\circ$$ ∘ computed tomography (CT) scan we show that the specially selected 60 micron tracer particles could be imaged in less than 3 seconds with a signal-to-noise ratio between the tracers and the fluid of 2.5, sufficient to achieve proper volumetric segmentation at each time step. In the pipe flow, continuous Lagrangian particle trajectories were obtained, after which all the standard techniques used for PTV or PIV (taken at visible wave lengths) could also be employed for TXPTV data. And, with TXPTV we can examine flows inaccessible with visible wave lengths due to opaque media or numerous refractive interfaces. In the case of opaque porous media we were able to observe material accumulation and pore clogging, and for flow with Taylor bubble we can trace the particles and hence obtain velocities in the liquid film between the wall and bubble, with thickness of liquid film itself also simultaneously obtained from the volumetric reconstruction after segmentation. While improvements in scan speed are anticipated due to continuing improvements in CT system components, we show that for the flows examined even the presently available CT systems could yield quantitative flow data with the primary limitation being the quality of available flow tracers. Graphic abstract

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Visualizing Fluid Flows With X-Rays

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2007-37023 ◽

2007 ◽

Cited By ~ 4

Author(s):

Theodore J. Heindel ◽

Terrence C. Jensen ◽

Joseph N. Gray

Keyword(s):

Computed Tomography ◽

Flow Visualization ◽

Three Dimensional ◽

Fluid Flows ◽

X Rays ◽

Radiographic Images ◽

Optical Access ◽

X Ray ◽

X Ray Computed ◽

Density Map

There are several methods available to visualize fluid flows when one has optical access. However, when optical access is limited to near the boundaries or not available at all, alternative visualization methods are required. This paper will describe flow visualization using an X-ray system that is capable of digital X-ray radiography, digital X-ray stereography, and digital X-ray computed tomography (CT). The unique X-ray flow visualization facility will be briefly described, and then flow visualization of various systems will be shown. Radiographs provide a two-dimensional density map of a three dimensional process or object. Radiographic images of various multiphase flows will be presented. When two X-ray sources and detectors simultaneously acquire images of the same process or object from different orientations, stereographic imaging can be completed; this type of imaging will be demonstrated by trickling water through packed columns and by absorbing water in a porous medium. Finally, local time-averaged phase distributions can be determined from X-ray computed tomography (CT) imaging, and this will be shown by comparing CT images from two different gas-liquid sparged columns.

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Measurement of the local velocity of the solid phase and the local solid hold-up in a three-phase flow by X-ray based particle tracking velocimetry (XPTV)

Chemical Engineering Science ◽

10.1016/s0009-2509(03)00010-1 ◽

2003 ◽

Vol 58 (9) ◽

pp. 1721-1729 ◽

Cited By ~ 25

Author(s):

A Seeger ◽

U Kertzscher ◽

K Affeld ◽

E Wellnhofer

Keyword(s):

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Solid Phase ◽

Phase Flow ◽

Local Velocity ◽

X Ray ◽

Three Phase ◽

Three Phase Flow

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Coloured Tracer Particles Employed for 3-D Particle Tracking Velocimetry (PTV) in Gas Flows

Notes on Numerical Fluid Mechanics and Multidisciplinary Design - Imaging Measurement Methods for Flow Analysis ◽

10.1007/978-3-642-01106-1_10 ◽

2009 ◽

pp. 93-102 ◽

Cited By ~ 2

Author(s):

Dominique Tarlet ◽

Christian Bendicks ◽

Robert Bordás ◽

Bernd Wunderlich ◽

Dominique Thévenin ◽

...

Keyword(s):

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Gas Flows ◽

Tracer Particles

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X-Ray Particle Tracking Velocimetry in Fluidized Beds

Volume 1: Symposia, Parts A, B and C ◽

10.1115/fedsm2009-78150 ◽

2009 ◽

Cited By ~ 2

Author(s):

Joshua B. Drake ◽

Lie Tang ◽

Theodore J. Heindel

Keyword(s):

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Fluidized Beds ◽

Tracer Particle ◽

High Heat ◽

Inert Material ◽

X Ray ◽

Bubbling Bed ◽

High Heat Transfer ◽

Biomass Particles

Fluidized beds are commonly found in the chemical and energy processing industries because of their low pressure drop, uniform temperature distribution, and high heat transfer rates. For example, in biomass gasification, biomass particles are injected into a heated bubbling bed of inert material (typically refractory sand) that volatilizes to form a flammable gas. However, the movement of the biomass particle through the bubbling bed is difficult to quantify because the systems are opaque. This paper describes X-ray particle tracking velocimetry (XPTV) applied to fluidized beds, where X-ray flow visualization is used to track the location of a single fabricated tracer particle as a function of time in a fluidized bed to study the bed/particle hydrodynamics. Using stereoscopic X-ray imaging, the 3D position of the tracer particle as a function of time is determined, from which tracer particle velocity can be calculated. Details and challenges of the XPTV process are also summarized.

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Statistical Particle Tracking Velocimetry Using Molecular and Quantum Dot Tracer Particles

Fluids Engineering ◽

10.1115/imece2005-80051 ◽

2005 ◽

Cited By ~ 1

Author(s):

Jeffrey S. Guasto ◽

Peter Huang ◽

Kenneth S. Breuer

Keyword(s):

Quantum Dots ◽

Particle Tracking ◽

Particle Tracking Velocimetry ◽

Experimental Validation ◽

Drop Out ◽

Tracer Particles ◽

Fluorescence Intermittency ◽

Distributed Tracking ◽

Fluorescent Molecules ◽

Measured Particle

We present the theory and experimental validation of a particle tracking velocimetry algorithm developed for application with nanometer-sized tracer particles such as fluorescent molecules and quantum dots (QDs). Traditional algorithms are challenged by extremely small tracers due to difficulties in determining the particle center, shot noise, high drop-in/drop-out and, in the case of quantum dots, fluorescence intermittency (blinking). The algorithms presented here determine real velocity distributions from measured particle displacement distributions by statistically removing randomly distributed tracking events. The theory was verified through tracking experiments using 54 nm flourescent dextran molecules and 6 nm QDs.

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