A4 Conference proceedings

Image Analysis of Bubbling Mode Condensation Oscillations in Horizontal Sparger


Open Access publication

Publication Details
Authors: Hujala Elina, Tanskanen Vesa, Patel Giteshkumar, Hyvärinen Juhani
Publication year: 2019
Language: English
Title of parent publication: Proceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18
eISBN: 978-0-89448-767-5
JUFO-Level of this publication: 2
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2019090326570

Abstract

Pattern recognition based image analysis algorithm was developed for analyzation of bubbling mode
condensation oscillations in horizontal spargers. Safety relief valve test rig SEF-POOL was filled with a
heated up (85 oC) water. The high mass flux steam (180 kg/(m2s) was pushed through a horizontal sparger
(16 mm). The SEF-INF2 experiment was recorded using a high-speed video camera with a frame rate of
2800 fps. An improved image processing and analysis procedure have been applied to the video material.
A new algorithm can deal with multiple simultaneous bubbles that can disappear for a while during the
condensation. Features of the oscillating bubbles, e.g. formation frequency, lifetime, surface velocity, and
acceleration, have been evaluated. The evaluated properties of the bubbles were also applied to CFD simulations, where the algorithm was used to determine critical wavelengths in succession to establish the
most suitable grid density for the simulations. The preliminary results look promising. A large frame rate
(2800 fps) yields significant information about condensation oscillations. Consequently, the bubble
properties and oscillations are captured better than before. The accuracy of the pattern recognition
algorithm has also been increased. 67 bubbles were tracked. Bubble mean lifetime was 0.0247 s, mean
time difference between bubble formations was 0.0140 s which corresponds to 71.6 Hz formation
frequency. 2D surface velocities and accelerations can now be estimated in all angles, which makes image
analysis an effective tool in validation efforts of interfacial area and heat transfer models for numerical.


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Last updated on 2020-20-03 at 10:03