Noninvasive Tomographic and Velocimetric Monitoring of Multiphase Flows

Abstract

A condensed review of recent advances accomplished in the development and the applications of noninvasive tomographic and velocimetric measurement techniques to multiphase flows and systems is presented. In recent years utilization of such noninvasive techniques has become widespread in many engineering disciplines that deal with systems involving two immiscible phases or more. Tomography provides concentration, holdup, or 2D or 3D density distribution of at least one component of the multiphase system, whereas velocimetry provides the dynamic features of the phase of interest such as the flow pattern, the velocity field, the 2D or 3D instantaneous movements, etc. The following review is divided into two parts. The first part summarizes progress and developments in flow imaging techniques using γ-ray and X-ray transmission tomography; X-ray radiography; neutron transmission tomography and radiography; positron emission tomography; X-ray diffraction tomography; nuclear magnetic resonance imaging; electrical capacitance tomography; optical tomography; microwave tomography; and ultrasonic tomography. The second part of the review summarizes progress and developments in the following velocimetry techniques: positron emission particle tracking; radioactive particle tracking; cinematography; laser-Doppler anemometry; particle image velocimetry; and fluorescence particle image velocimetry. The basic principles of tomography and velocimetry techniques are outlined, along with advantages and limitations inherent to each technique. The hydrodynamic and structural information yielded by these techniques is illustrated through a literature survey on their successful applications to the study of multiphase systems in such fields as particulate solids processes, fluidization engineering, porous media, pipe flows, transport within packed beds and sparged reactors, etc.

Bed height and material density effects on fluidized bed hydrodynamics

“…Contrary to the invasive techniques, noninvasive techniques are able to measure several of the characteristics listed above. According to Chaouki et al (1997), noninvasive techniques can be classified into tomography and radiography techniques and velocimetry techniques. Tomographic and radiographic techniques are divided into two categories: nuclear based imaging techniques like gamma-ray computed tomography (GRT), X-ray computed tomography (XCT), positron emission tomography (PET), X-ray diffraction tomography (XDT), X-ray and neutron transmission radiography, nuclear magnetic resonance imaging (MRI or NMRI), and non-nuclear based techniques like electrical capacitance tomography (ECT), optical tomography, and ultrasonic tomography.…”

“…Gammaray tomography (GRT) uses a gamma-ray source and detector to quantify the gamma-ray attenuation through an object. The attenuation provides a measure of the local mass density distribution along the path traversed by the gamma beam (Chaouki et al, 1997). Patel et al (2008) used GRT to determine the gas maldistribution of a gas-solid fluidized bed drier and how the gas maldistribution was affected by various parameters, such as particle size, particle density, and superficial gas velocity.…”

“…This technique is safer and faster than nuclear based techniques, it also provides more flexibility to accommodate large or small vessels. However, the spatial resolution provided is lower than the nuclear based techniques (Chaouki et al, 1997). Du et al (2003) used the ECT technique to study the dynamic behavior of a turbulent gas-solid fluidized bed.…”

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

“…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).…”

Experimental investigation of residual saturation in mixed-wet porous media using a pore-scale approach

“…MCT is a non-invasive technique that reveals the internal structure of an object by capturing variations in density and atomic composition. Thus, MCT images give a representation of the pore geometry of a system Chaouki et al (1997) and Karpyn et al (2010). In dry granular samples, the strong contrast between the solid phase and the pore space provides information for studying the porosity distribution of the system Ketcham and Carlson (2001).…”