X-Ray Analysis of Fluidized Beds and Other Multiphase                    Systems

Yates, J.G.; Cheesman, David; Lettieri, Paola; Newton, David E.

doi:10.14356/kona.2002016

Cited by 21 publications

(15 citation statements)

References 22 publications

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“…Noninvasive measurement techniques are valuable because they provide insight into the flow behavior and general hydrodynamic characteristics of multiphase flow and opaque systems (Yates et al, 2002). Noninvasive X-ray techniques such, as X-ray computed tomography (CT), generate a 3D image of the object of interest.…”

Section: Motivationmentioning

confidence: 99%

“…Noninvasive techniques are valuable because they provide insight into the flow behavior and general hydrodynamic characteristics of multiphase flow and opaque systems (Yates et al, 2002). There are several noninvasive techniques used to measure gas/liquid holdup, pressure drop, flow regime, bubble size and distribution, and gas and liquid velocity.…”

Section: Noninvasive Techniquesmentioning

confidence: 99%

“…X-rays have been used to study gas-solid fluidized beds as well as two and three phase fluidized systems for more than 50 years (Yates et al, 2002). They are commonly employed in noninvasive techniques because they are safer than other nuclear based techniques which cannot be turned on and off at will, have high resolution, and can be controlled by varying the voltage or current to improve penetration or contrast (Franka, 2008).…”

Section: Noninvasive X-ray Techniquesmentioning

confidence: 99%

See 2 more Smart Citations

Bed height and material density effects on fluidized bed hydrodynamics

Escudero

Heindel

2011

Chemical Engineering Science

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Section: Motivationmentioning

confidence: 99%

Section: Noninvasive Techniquesmentioning

confidence: 99%

Section: Noninvasive X-ray Techniquesmentioning

confidence: 99%

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Bed height and material density effects on fluidized bed hydrodynamics

Escudero

Heindel

2011

Chemical Engineering Science

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“…Multiple non-invasive quantitative flow visualisation techniques have been reviewed in the literature over the years (Chaouki et al 1997;Dudukovic 2000;Duke 2015;Heindel 2011;Kastengren and Powell 2014;Yates et al 2002). One of the first applications of X-ray imaging for visualisation of air bubbles in gas-solid fluidised beds was performed in the 1950s and 1960s (Grohse 1955;Rowe and Partridge 1997).…”

Section: Introductionmentioning

confidence: 99%

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

et al. 2016

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efficiency of such engines. Among others, the fuel injection equipment (FIE) is a key component for improving the efficiency of environmentally friendly engines. Recent advances dictate the use of extra high injection pressures, of the order of 3000 bar and tiny flow passages (injection holes) of the order of 100-250 μm in diameter, for improved fuel atomisation and combustion efficiency. Under these circumstances, cavitation has been found to develop inside fuel injection nozzles at the early studies of Badock et al. (1999), Bergwerk (1959), Chaves et al. (1995) and Nurick (1976), followed by Arcoumanis et al. (2000), Blessing et al. (2003), Mitroglou et al. (2014) and Roth et al. (2002) in more realistic real-size nozzle geometries offering optical access; equally helpful studies performed in transparent enlarged nozzle replicas [selectively (Andriotis et al. 2008;Arcoumanis et al. 2000;Miranda et al. 2003; Mitroglou and Gavaises 2013;Powell et al. 2000)] also indicate that cavitation plays an increasingly significant role in the nozzle's internal flow structure and development. Cavitation inside an injection hole is believed to enhance spray atomisation, either directly through the implosion of cavitation bubbles or indirectly because it increases turbulence in the nozzle flow (Badock et al. 1999;Walther 2002); unfortunately, under certain circumstances induces erosion (Dular and Petkovšek 2015;Koukouvinis et al. 2016) that may lead to catastrophic failures. Moreover, cavitation inside the injection holes promotes shot-toshot spray instabilities (Mitroglou et al. 2011(Mitroglou et al. , 2012Suh and Lee 2008), which, in turn, are responsible for poor combustion efficiency and increased emissions (Hayashi et al. 2013). Two distinct macroscopic forms of cavitation have been identified, which are referred to as geometryinduced and vortex or 'string' cavitation. The former can be, partially or totally, suppressed by appropriate design of the inlet hole curvature and non-cylindrical injection hole Abstract The flow inside a purpose built enlarged singleorifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and highspeed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can ...

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“…The simplest use of a combination of an X-ray source and a detector is by recording the transmission images after absorption from the sample in a radiography setup. X-ray radiography has been used to investigate hopper flow of sand [7] as well as the dynamics of granular matter in fluidized beds [8,9,10]. The addition of tomography, i.e.…”

Section: X-ray Radiographymentioning

confidence: 99%

Monitoring three-dimensional packings in microgravity

Frank-Richter

Börngen

et al. 2014

Granular Matter

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We present results from experiments with granular packings in three dimensions in microgravity as realized on parabolic flights. Two different techniques are employed to monitor the inside of the packings during compaction: (1) X-ray radiography is used to measure in transmission the integrated fluctuations of particle positions. (2) Stress-birefringence in three dimensions is applied to visualize the stresses inside the packing. The particle motions below the transition into an arrested packing are found to produce a well agitated state. At the transition, the particles lose their energy quite rapidly and form a stress network. With both methods, non-arrested particles (rattlers) can be identified. In particular, it is found that rattlers inside the arrested packing can be excited to appreciable dynamics by the restaccelerations (g-jitter) during a parabolic flight without destroying the packings. At low rates of compaction, a regime of slow granular cooling is identified. The slow cooling extends over several seconds, is described well by a linear law, and terminates in a rapid final collapse of dynamics before complete arrest of the packing.

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X-Ray Analysis of Fluidized Beds and Other Multiphase Systems

Cited by 21 publications

References 22 publications

Bed height and material density effects on fluidized bed hydrodynamics

Bed height and material density effects on fluidized bed hydrodynamics

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

Monitoring three-dimensional packings in microgravity

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