A1 Journal article (refereed), original research

Pattern recognition algorithm for analysis of chugging direct contact condensation


Open Access publication

Publication Details
Authors: Hujala Elina, Tanskanen Vesa, Hyvärinen Juhani
Publisher: Elsevier
Publication year: 2018
Language: English
Related Journal or Series Information: Nuclear Engineering and Design
Volume number: 332
Start page: 202
End page: 212
Number of pages: 11
ISSN: 0029-5493
eISSN: 1872-759X
JUFO-Level of this publication: 3
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2018092736727

Abstract


Direct
contact condensation of steam bubbles in a boiling water reactor suppression
pool has long been studied utilizing video recording of experiments. The use of
video recording enables observation of the behaviour of the bubble surface area
and can assist in validation of computational fluid dynamics models.





A direct
contact condensation experiment of the suppression pool test facility PPOOLEX
was recorded using high-speed cameras. The recorded video material was used for
development of a pattern recognition and data analysis algorithm. 300 fps video
of 48 s duration was cut into frames with a resolution of 768 px x 768 px. The
side profile of the bubbles was identified and the volumes and surface areas of
the bubbles were evaluated using a voxel-based method.





The purpose
of the algorithm was to determine the shape and size of steam bubbles during
their formation, expansion, collapse and re-formation. The most probabilistic
chugging frequencies were estimated. The bubble geometry data were also used to
determine the velocity and acceleration of the phase interface, as condensation
induced Rayleigh-Taylor instability develops on the bubble surface during the
bubble collapse, as the heavy phase accelerates towards the light phase.
Knowledge of the critical wave length is necessary for mesh spacing in CFD
calculations.





The
algorithm appears to be promising. Some limitations exist and approximations
need to be made due to the challenging video shooting conditions. The algorithm
works well for cylindrical bubbles and provides important data on the dynamics
of the phase interface necessary for numerical modelling of direct contact
condensation.


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Last updated on 2019-13-03 at 12:00