Colombo, M, Thakrar, R, Fairweather, M et al. (1 more author) (2017) Assessment of Semi-Mechanistic Bubble Departure Diameter Modelling for the CFD Simulation of Boiling Flows. In: Proceedings of the 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics. 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17), 03-08 Sep 2017, Xi’an, Shaanxi, China.
Abstract
In Eulerian-Eulerian two-fluid computational fluid dynamic (CFD) models, increasingly often applied to the prediction of nucleate boiling in nuclear reactor thermal hydraulics, boiling at the wall is usually accounted for by partitioning the heat flux between the different mechanisms of heat transfer involved. Between the numerous closures required, the bubble departure diameter in particular has a significant influence on the predicted interfacial area concentration and void distribution within the flow. In the present work, and following evidence of the limited accuracy and reliability of the empirically-based correlations which are applied normally in CFD models, more mechanistic formulations of bubble departure have been introduced into the STAR-CCM+ code. The performance of these models, based on a balance of the hydrodynamic forces acting on a bubble, and their compatibility with existing implementations in a CFD framework, are assessed against two different data sets for vertically upward subcooled boiling flows. In general, a significant amount of modelling is required by these mechanistic models and some recommendations are made on different modelling choices. The model is extended to include a more physically-consistent coupled calculation of the frequency of bubble departure and the modelling of the local subcooling acting on the bubble cap is analyzed. In general, predictions of void distribution and wall temperature reach a satisfactory accuracy, even if numerous numerical and modelling uncertainties are still present. In view of this, several areas for future work and modelling improvement are identified.
Metadata
Item Type: | Proceedings Paper |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This is an author produced version of a paper published in the Proceedings of the 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics. All rights reserved. |
Keywords: | Nucleate boiling, computational fluid dynamics, bubble departure diameter, semi-mechanistic model |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 01 Mar 2018 11:30 |
Last Modified: | 01 Mar 2018 11:42 |
Status: | Published |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:128025 |