X‐ray‐Based Flow Visualization and Measurement

Seeger, A.; Affeld, K.; Goubergrits, Leonid; Kertzscher, Ulrich; Wellnhofer, Ernst; Delfos, R.

doi:10.1111/j.1749-6632.2002.tb04580.x

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…Recently, Seeger et al 267 have developed a methodology that extracts the information concerning continuous or discreet phase is extracted using X-ray-based flow visualization and X-ray-based particle tracking velocimetry (PTV). Heindel 268 has used flash X-ray radiography (FXR) to visualize rising air bubbles in fiber suspension. The FXR technique allows for bubble visualization in the bulk suspension and the images of bubbles reveal that the bubble rise characteristics and patterns are highly dependent on suspension properties.…”

Section: Bubble Trajectoriesmentioning

confidence: 99%

Bubble Formation and Bubble Rise Velocity in Gas−Liquid Systems: A Review

Kulkarni

Joshi

2005

Ind. Eng. Chem. Res.

657

310

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The formation of gas bubbles and their subsequent rise due to buoyancy are very important fundamental phenomena that contribute significantly to the hydrodynamics in gas-liquid reactors. The rise of a bubble in dispersion can be associated with possible coalescence and dispersion followed by its disengagement from the system. The phenomenon of bubble formation decides the primitive bubble size in the system (which latter attains an equilibrium size), whereas the rise velocity decides the characteristic contact time between the phases which governs the interfacial transport phenomena as well as mixing. In view of their importance, we herein present a comprehensive review of bubble formation and bubble rise velocity in gas-liquid systems. The emphasis of this review is to illustrate the present status of the subjects under consideration and to highlight the possible future directions for further understanding of the subject. The bubble formation at a single submerged orifice and on multipoint sieve trays in Newtonian as well as non-Newtonian stagnant and flowing liquids is discussed in detail, which includes its mechanism as well as the effect of several system and operating parameters on the bubble size. The comparison of results has shown that the formulation of Gaddis and Vogelpohl 22 is the most suitable for the estimation of bubble size in stagnant liquids. The special cases, such as bubble formation in reduced gravity conditions and weeping and in flowing liquids, are discussed in detail. The section on the rise of a gas bubble in liquid covers the various parameters governing bubble rise and their effect on the rise velocity. A comprehensive comparison of the various formulations is made by validating the predictions with experimental data for Newtonian as well as non-Newtonian liquids, published over last several decades. The results highlight that for the estimation of rise velocity in (i) pure Newtonian liquids, (ii) contaminated Newtonian liquids, and (iii) non-Newtonian liquids, the formulation based on the wave theory by Mendelson,190 Nguyen's formulation, 155 and the formulation by Rodrigues, 153 (last two, based on the dimensional analysis), respectively are the most suitable. The motion of bubbles in non-Newtonian liquids and the reason behind the discontinuity in the velocity are also discussed in detail. The bubble rise is also analyzed in terms of the drag coefficient for different system parameters and bubble sizes.

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Section: Bubble Trajectoriesmentioning

confidence: 99%

Bubble Formation and Bubble Rise Velocity in Gas−Liquid Systems: A Review

Kulkarni

Joshi

2005

Ind. Eng. Chem. Res.

657

310

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“…Most recently, X-ray-based particle tracking velocimetry (XPTV) has been employed to study flow phenomena within two and three phased bubble columns. − Seeger et al first employed XPTV to study 2D flow in a water-filled bubble column with low void fraction as a benchmark against optical methods . This method was then extended to three dimensions with the use of a second X-ray source and detector.…”

Section: Introductionmentioning

confidence: 99%

“…Seeger el al. extended this method to observe fluid dispersion and measure solid dispersion and solid-phase velocities in a three-phase bubble column by matching the X-ray attenuating particles to the density and size of the solid phase. , …”

Section: Introductionmentioning

confidence: 99%

Flow Field Visualization in Structured Packing Using Real Time X-ray Radiography

Owens

Kossmann

Farone

et al. 2009

Ind. Eng. Chem. Res.

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This research developed an experimental method for validating the CFD representation of single-phase (vapor) flow through structured packing. Real time X-ray radiography was used to visualize fluid streamlines in structured packing by tracking neutrally buoyant X-ray absorbing particles entrained in water flow. Flow through the packing was found to be uniform, whereas flow at the packing element joints exhibited chaotic flow and recirculation zones. Individual radiographs were analyzed to determine particle displacement and compute local velocities. This data could be used to validate existing computational fluid dynamics (CFD) models, including fluids other than water through the use of similarity theory.

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“…X-ray methods work around the same process, the only difference being the higher attenuation rate due to the lower energy photons being absorbed more easily. Axel Seeger and his team (Seeger et al 2002) looked into using two different methods to visualise a multiphase flow; the first method being measurement of the three dimensional velocity field by X-ray based particle tracking velocimetry (PTV) where a single image was taken every 20 ms resulting in 25 image pairs per second, this could give up 1000 images made from 500 image pairs. The second method being liquid flow visualisation in a bubble column by injecting an X-ray absorbing liquid.…”

Section: Photon-based Radiography and Tomographymentioning

confidence: 99%

Wet steam measurement techniques

Walker

Barham²,

Giddings

et al. 2018

Reviews in Chemical Engineering

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Abstract In recent years a greater need for power station efficiency has become evident; improving turbine blade efficiency is one of the methods proposed. This efficiency depends upon the wetness of the steam that comes into contact with the blades of the low-pressure turbine stage in general and all turbines in nuclear power generation. Therefore, measurement of the moisture content of the steam in real time in conjunction with an accurate measure of steam velocity can give an overall mass flow re-entering the turbine, allowing for a feedback control. The system can rely on one technique that can measure suspended droplets and wall-bound liquid film, or a combination of techniques can operate together. This work gives a comprehensive review of the different techniques used to measure the moisture content including the liquid film and moisture content and techniques that can give measurements on both simultaneously. Each technique has its strengths and weaknesses, and they were analysed to see which technique works best overall and which techniques can be used together.

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X‐ray‐Based Flow Visualization and Measurement

Cited by 8 publications

References 6 publications

Bubble Formation and Bubble Rise Velocity in Gas−Liquid Systems: A Review

Bubble Formation and Bubble Rise Velocity in Gas−Liquid Systems: A Review

Flow Field Visualization in Structured Packing Using Real Time X-ray Radiography

Wet steam measurement techniques

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