Toward full simulations for a liquid metal blanket. Part 2: Computations of MHD flows with volumetric heating for a PbLi blanket prototype at Ha~104 and Gr~1012

2021 ◽  
Author(s):  
Long Chen ◽  
Sergey Smolentsev ◽  
Ming-Jiu Ni
Keyword(s):  
Pressure Drop ◽  
Liquid Metal ◽  
Mhd Flow ◽  
Mhd Flows ◽  
Volumetric Heating ◽  
Flow Equations ◽  
Electrically Conducting ◽  
Fine Mesh ◽  
Fusion Neutrons ◽  
Flow Effects

Abstract On the pathway toward full simulations for a liquid metal blanket, this Part 2 extends a previous study of purely MHD flows in a DCLL blanket in Ref. 1 [Chen, L., Smolentsev, S., and Ni, M. J. (2020)] to more general conditions when the MHD flow is coupled with heat transfer. The simulated prototypic blanket module includes all components of a real liquid metal blanket system, such as supply ducts, inlet and outlet manifolds, multiple poloidal ducts and a U-turn zone. Volumetric heating generated by fusion neutrons is added to simulate thermal effects in the flowing PbLi breeder. The MHD flow equations and the energy equation are solved with a DNS-type finite-volume code “MHD-UCAS” on a very fine mesh of 470×10^6 cells. The applied magnetic field is 5 T (Hartmann number Ha~10^4), the PbLi velocity in the poloidal ducts is 10 cm/s (Reynolds number Re~10^5), whereas the maximum volumetric heating is 30 MW/m^3 (Grashof number Gr~10^12). Four cases have been simulated, including forced- and mixed-convection flows, and either an electrically conducting or insulating blanket structure. Various comparisons are made between the four computed cases and also against the purely MHD flows computed earlier in Ref. \cite{1} with regards to the (1) MHD pressure drop, (2) flow balancing, (3) temperature field, (4) flows in particular blanket components, and (5) 3D and turbulent flow effects. The strongest buoyancy effects were found in the poloidal ducts. In the electrically non- conducting blanket, the buoyancy forces lead to significant modifications of the flow structure, such as formation of reverse flows, whereas their effect on the MHD pressure drop is relatively small. In the electrically conducting blanket case, the buoyancy effects on the flow and MHD pressure drop are almost negligible.

Application of Various Electromagnetic Coupling Modes for the Better MHD Flow Distribution and Thermal Management Within a Liquid Metal Manifold

2018 ◽  
Vol 10 (05) ◽  
pp. 1850052 ◽  
Author(s):  
Mohammad Farahi Shahri ◽  
Alireza Hossein Nezhad
Keyword(s):  
Liquid Metal ◽  
Electromagnetic Coupling ◽  
Flow Distribution ◽  
Mhd Flow ◽  
Electrically Conducting ◽  
Uniform Distributions ◽  
Flow And Heat Transfer ◽  
Supply Channel ◽  
Coupling Mode ◽  
Side Walls

In this work, 12 different electromagnetic coupling modes are considered by assuming the side walls and Hartmann walls of supply channel, expansion channel and three sub-channels of a liquid metal manifold to be electrically conducting or electrically insulating separately. The main purpose of this study is to identify the best mode from the viewpoint of uniform distributions of the flow and heat transfer through the manifold. To prevent the heat augmentation through the manifold sub-channels, it is highly necessary to have a uniform velocity distribution therein. Numerical results demonstrate that the electromagnetic coupling mode in which all Hartmann walls and all side walls of the manifold are electrically conducting has the best flow distribution within the manifold and consequently it exhibits a uniform thermal distribution through the manifold without any significant heat load. It is also found that the smallest pressure drop and therefore the lowest required power to pump the liquid metal across the manifold is devoted to the mode in which only Hartmann walls of the expansion channel are electrically conducting.

scholarly journals Suction Injection Induced MHD Flow through Vertical Narrow Porous Channel with Permeable Properties

2019 ◽  
Vol 8 (4) ◽  
pp. 121-126
Keyword(s):  
Transverse Velocity ◽  
Rectangular Channel ◽  
Fluid Flows ◽  
Mhd Flow ◽  
Research Problem ◽  
Velocity Profiles ◽  
Current Research Problem ◽  
Flow Equations ◽  
Electrically Conducting ◽  
Permeability Parameter

The current research problem deals with fluid flows that are electrically conducting known as Magnetohydrodynamic(MHD) flow, viscous oscillatory and stratified fluid in a vertical long small geometry rectangular channel that has permeable property with one side being porous and the other side being nonporous. Corresponding fluid flow equations are simplified and hence solved by applying Lubrication approximation by using similarity transformation. The interpretations of the influences of various quantities that are involved to the problem on velocity profiles, pressure and density distributions are explained in detail. The results of the research problem shows that the Magnetohydrodynamic parameter encourages backflow nearer to the boundaries of the channel while permeability parameter influences the flow differently for axial and transverse velocity profiles. The results for =0 reduces to the results that are already available in the literature.The current research problem deals with fluid flows that are electrically conducting known as Magnetohydrodynamic(MHD) flow, viscous oscillatory and stratified fluid in a vertical long small geometry rectangular channel that has permeable property with one side being porous and the other side being nonporous. Corresponding fluid flow equations are simplified and hence solved by applying Lubrication approximation by using similarity transformation. The interpretations of the influences of various quantities that are involved to the problem on velocity profiles, pressure and density distributions are explained in detail. The results of the research problem shows that the Magnetohydrodynamic parameter encourages backflow nearer to the boundaries of the channel while permeability parameter influences the flow differently for axial and transverse velocity profiles. The results for =0 reduces to the results that are already available in the literature.

Numerical simulation of liquid-metal MHD flows in rectangular ducts

1990 ◽  
Vol 216 ◽  
pp. 161-191 ◽  
Author(s):  
A. Sterl
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Boundary Layers ◽  
Hartmann Number ◽  
Three Dimensional ◽  
Mhd Flow ◽  
Two Dimensional ◽  
Square Duct ◽  
Mhd Flows ◽  
Pressure Losses

To design self-cooled liquid metal blankets for fusion reactors, one must know about the behaviour of MHD flows at high Hartmann numbers. In this work, finite difference codes are used to investigate the influence of Hartmann number M, interaction parameter N, wall conductance ratio c, and changing magnetic field, respectively, on the flow.As liquid-metal MHD flows are characterized by thin boundary layers, resolution of these layers is the limiting issue. Hartmann numbers up to 103 are reached in the two-dimensional case of fully developed flow, while in three-dimensional flows the limit is 102. However, the calculations reveal the main features of MHD flows at large M. They are governed by electric currents induced in the fluid. Knowing the paths of these currents makes it possible to predict the flow structure.Results are shown for two-dimensional flows in a square duct at different Hartmann numbers and wall conductivities. While the Hartmann number governs the thickness of the boundary layers, the wall conductivities are responsible for the pressure losses and the structure of the flows. The most distinct feature is the side layers where the velocities can exceed those at the centre by orders of magnitude.The three-dimensional results are also for a square duct. The main interest here is to investigate the redistribution of the fluid in a region where the magnetic field changes. Large axial currents are induced leading to the ‘M-shaped’ velocity profiles characteristic of MHD flow. So-called Flow Channel Inserts (FCI), of great interest in blanket design, are investigated. They serve to decouple the load carrying wall from the currents in the fluid. The calculations show that the FCI is indeed a suitable measure to reduce the pressure losses in the blanket.

scholarly journals Physical Background, Computations and Practical Issues of the Magnetohydrodynamic Pressure Drop in a Fusion Liquid Metal Blanket

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 110
Author(s):  
Sergey Smolentsev
Keyword(s):  
Magnetic Field ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Complex Shape ◽  
Special Focus ◽  
Computational Tools ◽  
Mhd Flows ◽  
Pressure Losses ◽  
Physical Background ◽  
The Magnetic Field

In blankets of a fusion power reactor, liquid metal (LM) breeders, such as pure lithium or lead-lithium alloy, circulate in complex shape blanket conduits for power conversion and tritium breeding in the presence of a strong plasma-confining magnetic field. The interaction of the magnetic field with induced electric currents in the breeder results in various magnetohydrodynamic (MHD) effects on the flow. Of them, high MHD pressure losses in the LM breeder flows is one of the most important feasibility issues. To design new feasible LM breeding blankets or to improve the existing blanket concepts and designs, one needs to identify and characterize sources of high MHD pressure drop, to understand the underlying physics of MHD flows and to eventually define ways of mitigating high MHD pressure drop in the entire blanket and its sub-components. This article is a comprehensive review of earlier and recent studies of MHD pressure drop in LM blankets with a special focus on: (1) physics of LM MHD flows in typical blanket configurations, (2) development and testing of computational tools for LM MHD flows, (3) practical aspects associated with pumping of a conducting liquid breeder through a strong magnetic field, and (4) approaches to mitigation of the MHD pressure drop in a LM blanket.

A volumetrically heated jet: large-eddy structure and entrainment characteristics

1996 ◽  
Vol 325 ◽  
pp. 303-330 ◽  
Author(s):  
G. S. Bhat ◽  
R. Narasimha
Keyword(s):  
Large Scale ◽  
Laser Doppler Anemometry ◽  
Local Heating ◽  
Integral Model ◽  
Volumetric Heating ◽  
Electrically Conducting ◽  
Cloud Development ◽  
Entrainment Process ◽  
Centreline Velocity ◽  
Heat Injection

We report here an experimental study of a round vertical liquid jet that, after achieving a self-preserving state, is subjected to volumetric heating between two diametral stations. The heat injection is achieved by applying a voltage across the stations, the jet fluid having been rendered electrically conducting by the addition of acid. Using laser-induced fluorescence, digital image processing and laser-Doppler anemometry, the flow properties of the jet have been studied in detail. It is found that, with sufficient heating, the jet no longer grows linearly with height, and the decay of both centreline velocity and turbulence intensity is arrested, and may even be reversed just beyond the zone of heat addition; nevertheless the entrainment decreases, which is at variance with the hypotheses often made for modelling it. This behaviour is here attributed to the disruptive influence that, as the present experiments show, the volumetric heating has on the large-scale vortical structures in the jet, which are known to be largely responsible for the engulfment of ambient fluid that is the first step in the entrainment process. It is shown that a new non-dimensional heat release number correlates the observed data on changes in jet width. An integral model that would describe the effect of local heating is proposed, and implications for cloud development in the atmosphere are discussed.

scholarly journals Analisis Tingkat Sirkulasi Alamiah pada Liquid Metal Fast Breeder Reactor dengan Pendingin Na, NaK, Pb dan Pb-Bi

2019 ◽  
Vol 8 (3) ◽  
pp. 227-233
Author(s):  
Refi Juita ◽  
Dian Fitriyani
Keyword(s):  
Pressure Drop ◽  
Liquid Metal ◽  
Fast Breeder Reactor

Telah dilakukan analisis tingkat sirkulasi alamiah pada LMFBR (Liquid Metal Fast Breeder Reactor) dengan bahan pendingin Na, NaK, Pb dan Pb-Bi. Perhitungan neutronik dan termalhidrolik pada penelitian ini menggunakan program DTRIDI berbasis delphi7 yang merupakan program simulasi untuk desain teras tiga dimensi (xyz). Teras LMFBR dirancang dengan bahan bakar UN-PuN dan beroperasi pada daya 150 MWth. Simulasi diawali dengan perhitungan neutronik yang memberikan hasil faktor multiplikasi neutron yang digunakan untuk perhitungan termalhidrolik sehingga diperoleh distribusi temperatur dan penurunan tekanan. Analisis tingkat sirkukasi alamiah dilakukan dengan pendekatan kuasistatik, dimana laju aliran massa pendingin total diturunkan secara bertahap untuk mensimulasikan hilangnya daya pompa pada keadaan kecelakaan ULOF (Unprotected Lost Of Flow). Tingkat sirkulasi alamiah diperoleh dari grafik perpotongan antara pressure drop dan driving head sebagai fungsi dari laju alir pendingin total. Sirkulasi alamiah tercapai lebih cepat pada penggunaan bahan pendingin Pb dan Pb-Bi yaitu sekitar 27,5 % dari laju aliran pendingin mula-mula, sedangkan untuk penggunaan pendingin Na dan NaK hampir tidak terjadi sirkulasi alamiah yang berarti reaktor dalam keadaan bahaya jika terjadi kecelakaan ULOF.Kata kunci:  sirkulasi alamiah, LMFBR, ULOF, Na, NaK, Pb, Pb-Bi

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