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Anglart, H. (2021). Multilingual Dictionary of Nuclear Reactor Physics and Engineering. CRC Press
Open this publication in new window or tab >>Multilingual Dictionary of Nuclear Reactor Physics and Engineering
2021 (English)Book (Other (popular science, discussion, etc.))
Place, publisher, year, edition, pages
CRC Press, 2021
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-289422 (URN)978-0-367-47081-4 (ISBN)
Note

QC 20210201

Available from: 2021-01-28 Created: 2021-01-28 Last updated: 2022-06-25Bibliographically approved
Yang, B.-W., Anglart, H., Han, B. & Liu, A. (2021). Progress in rod bundle CHF in the past 40 years. Nuclear Engineering and Design, 376, Article ID 111076.
Open this publication in new window or tab >>Progress in rod bundle CHF in the past 40 years
2021 (English)In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 376, article id 111076Article in journal (Refereed) Published
Abstract [en]

Critical Heat Flux (CHF) prediction remains one of the most important tasks in thermal hydraulics of Light Water Reactors (LWR's). During recent years, tremendous progress has been made in understanding and predicting rod bundle CHF. However, due to the unique features associated with rod bundle subchannel systems, including complex and compact anisotropic geometry, non-uniform axial/radial heating, open channel interactions, periodic (positional) mixing vane grids (MVG's) mixing (Yang et al., 2014), and a broad range of operation conditions (Yang and Han et al., 2019), a precise prediction of CHF in rod bundles, entirely based on analytical methods without the support of any extensive experimental database, is still beyond the present modelling and computational capabilities. For Pressurized Water Reactors (PWR's), CHF occurs at a relatively low coolant quality and is primarily driven by the Departure from Nucleate Boiling (DNB) type event, which can be triggered by liquid sublayer dryout, bubble crowding, homogeneous nucleation, or other mechanisms causing local starvation of liquid under subcooled flow boiling or low quality saturated boiling conditions, and the dryout event, which describes CHF under a high void situation when liquid film on the fuel surface dries out, usually happens in a high quality saturated annular flow. Boiling Water Reactors (BWR's) operate at a relatively lower pressure and can reach much higher coolant qualities that correspond to annular two-phase flow conditions. This dominant CHF mechanism, dryout, is based on the gradual thinning and drying out of the liquid film. This paper provides an overview of the progress made in the experimental and analytical investigations of CHF in both PWR and BWR rod bundles during the past 40 years. A complete comprehensive concept map is developed to outline most of the key mechanistic CHF models covering the entire range of flow regimes. The limitation and the potential approaches for the application of mechanistic models to rod bundle CHF prediction are reviewed. This includes the recently proposed, rod bundle specific NHNM (Non-uniform heater Homogeneous Nucleation Model [Yang, 2017]). Various industrial empirical correlations are reviewed together with their corresponding subchannel codes and required rod bundle CHF experiments. The need for clear guidelines and standards for benchmarking new rod bundle CHF test facilities is discussed. Various approaches on investigating, understanding, modeling, and predicting the occurrence of rod bundle CHF are reviewed from mechanistic models, semi-empirical and empirical approaches to advanced CFD simulation. The achievements and limitations in those methods are discussed with suggestions for future advancement.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2021
Keywords
CHF, DNB, Dryout, Rod bundle, Models, Correlations, Liquid sublayer, Bubble crowding, Homogeneous nucleation
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-296197 (URN)10.1016/j.nucengdes.2021.111076 (DOI)000641696500003 ()2-s2.0-85101836668 (Scopus ID)
Note

QC 20210609

Available from: 2021-06-09 Created: 2021-06-09 Last updated: 2022-06-25Bibliographically approved
Fan, W., Li, H. & Anglart, H. (2020). A study of rewetting and conjugate heat transfer influence on dryout and post-dryout phenomena with a multi-domain coupled CFD approach. International Journal of Heat and Mass Transfer, 163, Article ID 120503.
Open this publication in new window or tab >>A study of rewetting and conjugate heat transfer influence on dryout and post-dryout phenomena with a multi-domain coupled CFD approach
2020 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 163, article id 120503Article in journal (Refereed) Published
Abstract [en]

In the present study, a multi-domain coupled computational fluid dynamics (CFD) approach is developed for the modeling of dryout and post-dryout heat transfer. For the fluid part, the thin film and gas core are modeled by the liquid film model and two-fluid model, respectively. For the solid part, the heating process is modeled by either using a constant heat source or solving the Joule heating problem. The fluid-solid conjugate heat transfer is calculated by using carefully designed coupling schemes which can automatically determine the operation mode for pre- and post-dryout regions. Unlike standalone simulations where only the inner wall temperature is predicted, coupled simulations are able to predict the outer wall temperature, allowing a direct comparison with experiments. Simulations were carried out for a wide range of flow conditions and validated against the corresponding steady state experiments. By newly introducing a film rewetting model, the current CFD code is capable of simulating the transient behavior of dryout. With the rewetting model, the coupled code successfully predicted the dryout hysteresis.

Place, publisher, year, edition, pages
Elsevier BV, 2020
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-285583 (URN)10.1016/j.ijheatmasstransfer.2020.120503 (DOI)000589421900086 ()2-s2.0-85091916992 (Scopus ID)
Note

QC 20201109

Available from: 2020-11-06 Created: 2020-11-06 Last updated: 2024-03-15Bibliographically approved
Fan, W., Cherdantsev, A. V. & Anglart, H. (2020). Experimental and numerical study of formation and development of disturbance waves in annular gas-liquid flow. Paper presented at 14th Conference on Research and Development in Power Engineering (RDPE), DEC 03-06, 2019, Warsaw, POLAND. Energy, 207, Article ID 118309.
Open this publication in new window or tab >>Experimental and numerical study of formation and development of disturbance waves in annular gas-liquid flow
2020 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 207, article id 118309Article in journal (Refereed) Published
Abstract [en]

Disturbance waves in a downwards annular gas-liquid flow were investigated experimentally and numerically in this study. In the experiment, the brightness-based laser-induced fluorescence (BBLIF) technique was utilized to obtain high-resolution spatiotemporal measurements for the film thickness. In the simulations, the two-phase system was simulated by the volume of fluid (VOF) method together with newly developed turbulence damping models, without which the turbulence level around the film surface is considerably under-predicted. Qualitative and quantitative comparisons were carried out for the experimental and numerical data, during which a novel method was developed to extract complex wave structures in a direct manner. Comparisons showed that the model is able to reproduce the main stages of flow evolution, including development of high-frequency initial waves, their coalesce into stable large-scale disturbance waves, generation of slow and fast ripples, and disruption of fast ripples into droplets. The main properties of modeled waves are in decent agreement with the measured ones, apart from noticeably rarer generation of ripples. The presented methods offer a new and promising option to model various energy technology systems, where annular two-phase flow occurs.

Place, publisher, year, edition, pages
Elsevier BV, 2020
Keywords
Annular flow, Disturbance waves, BBLIF, VOF, Turbulence damping
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-279884 (URN)10.1016/j.energy.2020.118309 (DOI)000558533200091 ()2-s2.0-85087996251 (Scopus ID)
Conference
14th Conference on Research and Development in Power Engineering (RDPE), DEC 03-06, 2019, Warsaw, POLAND
Note

QC 20200915

Available from: 2020-09-15 Created: 2020-09-15 Last updated: 2022-06-25Bibliographically approved
Bergagio, M., Fan, W., Thiele, R. & Anglart, H. (2020). Large eddy simulation of thermal mixing with conjugate heat transfer at BWR operating conditions. Nuclear Engineering and Design, 356, Article ID 110361.
Open this publication in new window or tab >>Large eddy simulation of thermal mixing with conjugate heat transfer at BWR operating conditions
2020 (English)In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 356, article id 110361Article in journal (Refereed) Published
Abstract [en]

Thermal fatigue occurs in most metals under cyclic heat loads and can threaten the structural integrity of metal parts. Detailed knowledge of these loads is of utter importance to prevent such issues. In this study, a large eddy simulation (LES) with wall-adapting local eddy viscosity (WALE) subgrid model is performed to better understand turbulent thermal mixing in an annulus with a pair of opposing cold inlets at a low axial level (z = 0.15 m) and with a pair of opposing hot inlets at a higher axial level (z = 0.80 m). Each inlet pair is 90 degrees from each other in the azimuthal direction. Conjugate heat transfer between fluid and structure is accounted for. The geometry simplifies a control-rod guide tube (CRGT) in a boiling water reactor (BWR). LES results are compared with measurement data. This is one of the first times BWR conditions are met in both experiments and LES: pressure equals 7.2 MPa, while the temperature difference between hot and cold inlets reaches 216 K. LES temperatures at the fluid-structure interface are fairly correlated with their experimental equivalents, with regard to mean values, local variances, and dangerous oscillation modes in fatigue-prone areas (z = 0.65 - 0.67 m). An elastic analysis of the structure is performed to evaluate stress intensities there. From them, cumulative fatigue usage factors (CUFs) are estimated and used as screening criteria in the subsequent frequency analysis of temperature time series at the fluid-structure interface. The likelihood of initiating a fatigue crack is linked to the maximum CUF, which is 3.2 x 10(-5) for a simulation time of similar to 10 s.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2020
Keywords
Turbulent mixing, Conjugate heat transfer, LES, WALE SGS model, High cycle thermal fatigue
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-266514 (URN)10.1016/j.nucengdes.2019.110361 (DOI)000503842900011 ()2-s2.0-85073569453 (Scopus ID)
Note

QC 20200205

Available from: 2020-02-05 Created: 2020-02-05 Last updated: 2022-06-26Bibliographically approved
Fan, W. & Anglart, H. (2020). varRhoTurbVOF 2: Modified OpenFOAM volume of fluid solvers with advanced turbulence modeling capability. Computer Physics Communications, 256, Article ID 107467.
Open this publication in new window or tab >>varRhoTurbVOF 2: Modified OpenFOAM volume of fluid solvers with advanced turbulence modeling capability
2020 (English)In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 256, article id 107467Article in journal (Refereed) Published
Abstract [en]

varRhoTurbVOF contains a set of OpenFOAM volume of fluid (VOF) solvers for turbulent isothermal multiphase flows, which are variable-density incompressible. Unlike their official counterparts, where Favre-averaged and Reynolds-averaged velocities coexist in different equations, new solvers use Favre-averaged velocities consistently in all equations. This major update introduces three main improvements to the previous version of varRhoTurbVOF. First, the implementation is extended to VOF solvers for isothermal and non-isothermal phase change two-phase flows, where the flow is no longer incompressible. Second, in order to introduce backward compatibility and to avoid code duplication, the turbulence model construction procedure is redesigned such that solvers can determine whether the variable-density effect is considered or not in the turbulence modeling part based on the input file at run time. Third, the Egorov turbulence damping model for omega-based turbulence models is implemented with its most recent developments. Plus, an extension to epsilon-based turbulence models is developed and implemented. Program summary Program Title: varRhoTurbVOF CPC Library link to program files: http://dx.doi.org/10.17632/4t8z8vzyvs.2 Developer's repository link: https://github.com/wenyuan- fan/varRhoTurbVOF_2 Licensing provisions: GPLv3 Programming language: C++ Journal reference of previous version: Wenyuan Fan, Henryk Anglart, 2020. varRhoTurbVOF: A new set of volume of fluid solvers for turbulent isothermal multiphase flows in OpenFOAM, Computer Physics Communications, 247, 106876. Does the new version supersede the previous version?: Yes Reasons for the new version: Implementation of new solvers and models; code redesign to maintain backward compatibility. Summary of revisions: The updated version mainly has three new features in comparison with the previous version: The issue addressed in [1] exists in all OpenFOAM VOF solvers where the variable-density effect is neglected in the turbulence modeling. In order to solve this issue for phase change VOF solvers, two additional solvers, namely, varRhoInterPhaseChangeFoam and varRhoInter CondensatingEvaporatingFoam, are implemented based on their official counterparts. The procedure of constructing the turbulence model inside individual solvers is redesigned. Using the new design, solvers will construct turbulence models with or without the variable-density effect being considered based on the user input. When the latter mode is activated, solvers will behave just like their official counterparts. In such a way, the backward compatibility of the code is achieved without introducing code duplications. The Egorov turbulence damping model [2], which is a popular approach to phenomenologically modify turbulence behaviors near a two-phase interface, is implemented. In addition to the original model, recent modifications, e.g., a new length scale calculation and asymmetric damping treatments [3], are implemented as well. The Egorov model only works with.-based turbulence models. In the new release, the model is extended to.-based turbulence models following the idea proposed in [4] such that the turbulence damping model is applicable to commonly used turbulence models. Nature of problem: Within the VOF framework, the mixture has a density changing with phases. However, in quite a few OpenFOAM VOF solvers, the variable-density effect is considered in the momentum equation but neglected in the turbulence modeling. As a result, Favre-averaged velocities and Reynolds-averaged velocities are used in the momentum equation and turbulence quantity equations, respectively and simultaneously, introducing a severe self-inconsistency. Solutions to this problem have been proposed in [1] with no backward compatibility support. Also, no phase change solvers are supported in the previous version. Another issue with turbulent VOF simulations is that, even with the correct implementation, certain modifications are still needed to correct the turbulence behavior around the interface. Solution method: The extension to phase change VOF solvers is straightforward according to [1]. Regarding the construction of turbulence models, two additional fields, namely, rhoTurb and rhoPhiTurb, are created and used in turbulence models. If the user chooses to use the variable-density turbulence models, real two-phase density rho and mass flux rhoPhi will be assigned to rhoTurb and rhoPhiTurb, respectively. Otherwise, rhoTurb and rhoPhiTurb will use unity and volume flux phi, respectively. This run time selection design enables solvers to operate in two modes, which guarantees the backward compatibility and avoids code duplications. The implementation of the turbulence damping model also takes the backward compatibility into account. At run time, the code will automatically determine whether the mixture density should be included in the turbulence damping model by checking the dimension of the corresponding equation. Additional comments: A manual is provided to introduce how the turbulence damping modeled is formulated and how to use the model. It should be emphasized that the Egorov damping model is a phenomenological model. Model parameters should be carefully selected for any given mesh and flow condition.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Volume of fluid, Variable-density effect, Turbulence modeling, Backward compatibility, Turbulence damping
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-281474 (URN)10.1016/j.cpc.2020.107467 (DOI)000564482200011 ()2-s2.0-85087282923 (Scopus ID)
Note

QC 20201021

Available from: 2020-10-21 Created: 2020-10-21 Last updated: 2022-06-25Bibliographically approved
Fan, W. & Anglart, H. (2020). varRhoTurbVOF: A new set of volume of fluid solvers for turbulent isothermal multiphase flows in OpenFOAM. Computer Physics Communications, 247, Article ID 106876.
Open this publication in new window or tab >>varRhoTurbVOF: A new set of volume of fluid solvers for turbulent isothermal multiphase flows in OpenFOAM
2020 (English)In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 247, article id 106876Article in journal (Refereed) Published
Abstract [en]

The volume of fluid (VOF) method is a popular approach for multiphase flow modeling. The open-source computational fluid dynamics (CFD) software, OpenFOAM, implements a variety of VOF-based solvers and provides users a wide range of turbulence models. Since isothermal multiphase flows under the VOF framework belong to the variable-density incompressible flow category, the isothermal VOF-based solvers in OpenFOAM fail to use the correct turbulence models. varRhoTurbVOF is designed to solve this issue and with the hope to replace all the corresponding existing solvers in the future. With the object-oriented paradigm, varRhoTurbVOF guarantees the usability, reusability and maintainability of the codes. Aside from turbulence modeling, all other features in the original solvers are preserved in varRhoTurbVOF. Program summary: Program Title: varRhoTurbVOF Program Files doi: http://dx.doi.org/10.17632/4t8z8vzyvs.1 Licensing provisions: GPLv3 Programming language: C++ Supplementary material: http://dx.doi.org/10.17632/7mp25kyb4p.4 Nature of problem: Under the VOF framework, the flow of the isothermal mixture belongs to the variable-density incompressible flow category. For such flows, VOF-based solvers of OpenFOAM fail to construct the correct governing equations for turbulence modeling. varRhoTurbVOF contains a set of newly designed VOF-based solvers which could use the desired governing equations for turbulence quantities. Solution method: varRhoTurbVOF creates a new class for variable-density incompressible turbulence models, which allows reusing the existing turbulence model template classes. A set of VOF-based solvers are then created to be able to construct variable-density incompressible turbulence models.

Place, publisher, year, edition, pages
Elsevier B.V., 2020
Keywords
CFD, OpenFOAM, Turbulence modeling, Variable-density incompressible flow, VOF, C++ (programming language), Incompressible flow, Isotherms, Multiphase flow, Object oriented programming, Open source software, Open systems, Reusability, Turbulence models, Governing equations, Incompressible turbulence, Multi-phase flow models, Object oriented paradigm, Variable density, Volume of fluid method, Volume of fluids, Computational fluid dynamics
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-263257 (URN)10.1016/j.cpc.2019.106876 (DOI)000503093400023 ()2-s2.0-85071451876 (Scopus ID)
Note

QC 20191106. QC 20200109

Available from: 2019-11-06 Created: 2019-11-06 Last updated: 2022-06-26Bibliographically approved
Li, H. & Anglart, H. (2019). Dryout prediction with CFD model of annular two-phase flow. Nuclear Engineering and Design, 349, 20-26
Open this publication in new window or tab >>Dryout prediction with CFD model of annular two-phase flow
2019 (English)In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 349, p. 20-26Article in journal (Refereed) Published
Abstract [en]

Two-phase flow and heat transfer are of interest to industrial applications due to its high efficiency. In a diabatic annular two-phase flow, the liquid film is depleted by both entrainment of liquid droplets and by evaporation. When the liquid film experiences almost complete depletion and cannot cover the wall, the heat transfer between the fluid and the channel wall significantly deteriorates, leading to the onset of boiling transition called dryout. While the dryout is milder than the departure from nucleate boiling (DNB) occurring in low quality two-phase flows, it could still challenge and damage the channel wall. As a result, the dryout occurrence needs to accurately predicted and avoided in practice, such as in boiling water reactors (BWRs). Research interests haven been recently focused on dryout prediction with annular flow modeling, with three fields of gas, droplets and liquid film accounted for. In the current study, one unified computational fluid dynamics (CFD) model for annular flow was developed for dryout applications. The model is employing a separate solver of two-dimensional conservation equations to predict propagation of a thin boiling liquid film on solid walls. The film model is coupled to a solver of three-dimensional conservation equations describing the gas core, which is assumed to contain a saturated mixture of vapor and liquid droplets. All the major interaction phenomena between the liquid film and the gas core flow have been accounted for, including the liquid film evaporation as well as the droplet deposition and entrainment. The resultant unified framework for annular flow has been applied to the swam-water flow with conditions typical for a BWR. The simulation results for the liquid film flow and dryout occurrence show favorable agreements with the available experimental data.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2019
Keywords
Annular two-phase flow, Dryout prediction, Liquid film, Droplet deposition and entrainment
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-252582 (URN)10.1016/j.nucengdes.2019.04.020 (DOI)000468113300003 ()2-s2.0-85064430579 (Scopus ID)
Note

QC 20190611

Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2022-06-26Bibliographically approved
Anglart, H. (2019). Initial entrained fraction at onset of annular flow. In: 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 20192019,: . Paper presented at 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019; Marriott Portland Downtown WaterfrontPortland; United States; 18 August 2019 through 23 August 2019 (pp. 1023-1034).
Open this publication in new window or tab >>Initial entrained fraction at onset of annular flow
2019 (English)In: 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 20192019,, 2019, p. 1023-1034Conference paper, Published paper (Refereed)
Abstract [en]

One of the frequently employed current models to predict the occurrence of dryout in boiling annular flows is using conservation equations to determine the liquid film mass flux. The accuracy of predictions of dryout depends to a large extend on the initial conditions, which are employed in the model. In this paper it is shown that the accuracy of predictions can be significantly improved if the initial entrained fraction of liquid is correlated to the flow conditions at the onset of annular flow. Using experimental data for liquid film flow rates in pipes with variable power distributions, a new closure relationship for the initial entrained fraction of liquid at the onset of annular flow is proposed.

National Category
Mechanical Engineering Energy Engineering
Identifiers
urn:nbn:se:kth:diva-268323 (URN)2-s2.0-85073715098 (Scopus ID)
Conference
18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019; Marriott Portland Downtown WaterfrontPortland; United States; 18 August 2019 through 23 August 2019
Note

QC 20200310

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2022-06-26Bibliographically approved
Fan, W., Li, H. & Anglart, H. (2019). Numerical investigation of spatial and temporal structure of annular flow with disturbance waves. International Journal of Multiphase Flow, 110, 256-272
Open this publication in new window or tab >>Numerical investigation of spatial and temporal structure of annular flow with disturbance waves
2019 (English)In: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, Vol. 110, p. 256-272Article in journal (Refereed) Published
Abstract [en]

Droplet entrainment is a crucial process for annular flow in terms of heat and mass transfer. Disturbance wave is believed to be a fundamental phenomenon which is closely related to entrainment. A 3D numerical simulation on disturbance waves and entrainment is carried out by using volume of fluid (VOF) method where no periodic boundary condition is used. Since VOF tracks the interface implicitly, a systematic method is developed for post-processing, with which disturbance waves. ripples, base film, and entrainment process are clearly visualized, and the stochastic and chaotic nature of two-phase flow is confirmed. Surfacewise distributions are generated for main wave parameters, and the streamwise developments of such quantities are shown to be consistent with experimental observations. Predictions for main wave parameters are in reasonable agreement with the experiment and empirical correlations. Current work shows the capability and promising application of investigating disturbance waves and entrainment with VOF method.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Disturbance wave, Entrainment, VOF, Periodic boundary
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-240699 (URN)10.1016/j.ijmultiphaseflow.2018.10.003 (DOI)000452945400019 ()2-s2.0-85054441195 (Scopus ID)
Note

QC 20190110

Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2024-03-18Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5595-1952

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