Imperial College London
Alternate

ProfessorChristosMarkides

Faculty of Engineering, Department of Chemical Engineering

Professor of Clean Energy Technologies
 
 
 
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Contact

 

+44 (0)20 7594 1601c.markides Website

 
 
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Location

 

404ACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Voulgaropoulos:2021:10.1016/j.ijmultiphaseflow.2021.103665,
author = {Voulgaropoulos, V and Patapas, A and Lecompte, S and Charogiannis, A and Matar, OK and De, Paepe M and Markides, CN},
doi = {10.1016/j.ijmultiphaseflow.2021.103665},
journal = {International Journal of Multiphase Flow},
pages = {103665--103665},
title = {Simultaneous laser-induced fluorescence and capacitance probe measurement of downwards annular gas-liquid flows},
url = {http://dx.doi.org/10.1016/j.ijmultiphaseflow.2021.103665},
volume = {142},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This study focuses on the characterisation of downwards annular gas-liquid (air-water) flows,  by employing a combi-nation of advanced laser-based and capacitance-based measurement methods.  A variant of laser-induced fluorescence(LIF),  referred  to  as  structured-planar  laser-induced  fluorescence  (S-PLIF),  eliminates  biases  commonly  encounteredduring film-thickness measurements of gas-liquid flows, due to refraction and reflection of the light at the interface.  Abespoke capacitance probe is also assembled to enable temporally resolved film-thickness measurements with high tem-poral resolution along the circumferential perimeter of the pipe.  We compare the film mean thickness, roughness, andprobability density functions obtained with each method.  We find that both methods are able to measure time-averagedfilm thickness to within<20% deviations from each other and from results obtained from the available literature.  Theresulting probe data suggest a biased (suppressed) standard deviation of the film thickness, which can be attributed toits working principle, i.e., measuring the film thickness averaged along the circumferential perimeter of the pipe.  Theauto-correlation functions of the time-traces provide an insight into the characteristic time-scales of the flows,  whichspan a range from∼10 ms for highly gas-sheared flows and increase to about 30 ms for the less turbulent falling films.The power spectral densities reveal modal frequencies that start from 2.5 Hz for falling films, and increase with the gasReynolds number by almost an order of magnitude.  The turbulent wave activity (slope in the power spectrum) reduceswith a decrease in gas shear, and shows similarities to the decay of homogeneous and isotropic turbulence.  The sizes ofthe bubbles entrained in the liquid film are measured from the S-PLIF images, and exhibit log-normal distribution thatbecome flatter with a decrease in the gas Reynolds number.  The normalised location of the bubbl
AU  - Voulgaropoulos,V
AU  - Patapas,A
AU  - Lecompte,S
AU  - Charogiannis,A
AU  - Matar,OK
AU  - De,Paepe M
AU  - Markides,CN
DO  - 10.1016/j.ijmultiphaseflow.2021.103665
EP  - 103665
PY  - 2021///
SN  - 0301-9322
SP  - 103665
TI  - Simultaneous laser-induced fluorescence and capacitance probe measurement of downwards annular gas-liquid flows
T2  - International Journal of Multiphase Flow
UR  - http://dx.doi.org/10.1016/j.ijmultiphaseflow.2021.103665
UR  - https://www.sciencedirect.com/science/article/pii/S0301932221001130?via%3Dihub
UR  - http://hdl.handle.net/10044/1/88207
VL  - 142
ER  -
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