Fast X-ray imaging of cavitating flows

A new method based on ultra-fast X-ray imaging was developed in this work for the investigation of the dynamics and the structures of complex two-phase flows. In this paper, cavitation was created inside a millimetric 2D Venturi-type test section, while seeding particles were injected into the flow....

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Bibliographic Details
Published in:Experiments in fluids 2017-11, Vol.58 (11), p.1-22, Article 157
Main Authors: Khlifa, Ilyass, Vabre, Alexandre, Hočevar, Marko, Fezzaa, Kamel, Fuzier, Sylvie, Roussette, Olivier, Coutier-Delgosha, Olivier
Format: Article
Language:English
Subjects:
Cavitation
Dynamic structural analysis
Engineering
Engineering Fluid Dynamics
Engineering Thermodynamics
Fluid- and Aerodynamics
Heat and Mass Transfer
High definition
Image processing
OTHER INSTRUMENTATION
Phases
Research Article
Two phase flow
Two-phase flows
Unsteady flow
Velocimetry
X-ray imaging
X-rays
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Summary:A new method based on ultra-fast X-ray imaging was developed in this work for the investigation of the dynamics and the structures of complex two-phase flows. In this paper, cavitation was created inside a millimetric 2D Venturi-type test section, while seeding particles were injected into the flow. Thanks to the phase-contrast enhancement technique provided by the APS (Advanced Photon Source) synchrotron beam, high definition X-ray images of the complex cavitating flows were obtained. These images contain valuable information about both the liquid and the gaseous phases. By means of image processing, the two phases were separated, and velocity fields of each phase were, therefore, calculated using image cross-correlations. The local vapour volume fractions were also obtained, thanks to the local intensity levels within the recorded images. These simultaneous measurements, provided by this new technique, afford more insight into the structure and the dynamic of two-phase flows as well as the interactions between them, and hence enable to improve our understanding of their behaviour. In the case of cavitating flows inside a Venturi-type test section, the X-ray measurements demonstrate, for the first time, the presence of significant slip velocities between the phases within sheet cavities for both steady and unsteady flow configurations.
ISSN:0723-4864
1432-1114
DOI:10.1007/s00348-017-2426-7